This document describes a study where Pt-Ru nanoparticles were supported on functionalized carbon nanofibers (CNF) using polyamidoamine (PAMAM) dendrimers. PAMAM dendrimers were anchored to carboxylated CNF and then used to encapsulate and disperse Pt-Ru nanoparticles on the CNF surface. The composite catalyst (20% Pt-Ru/PAMAM-CNF) showed better performance for methanol oxidation than a commercial 20% Pt-Ru/C catalyst based on cyclic voltammetry tests. Characterization with XRD, SEM and TEM showed the Pt-Ru nanoparticles were uniformly dispersed and small in size (2.6 nm) on the PA
Polyamidoamine (PAMAM) dendrimers has
been anchored on functionalized carbon nanofibers (CNF)
and supported Pt–Ru nanoparticles have been prepared with
NaBH4 as a reducing agent. The samples were characterized
by X-ray diffraction, scanning electron microscopy,
and transmission electron microscopy (TEM) analysis. It
was shown that Pt–Ru particles with small average size
(2.6 nm) were uniformly dispersed on PAMAM/CNF
composite support and displayed the characteristic diffraction
peaks of Pt face-centered cubic structure. The electrocatalytic
activities of the prepared-composites (20% Pt–Ru/PAMAMCNF)
were examined by using cyclic voltammetry for
oxidation of methanol. The electrocatalytic activity of the
CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode
for methanol oxidation showed better performance than that
of commercially available Johnson Mathey 20% Pt–Ru/C
catalyst. The results imply that CNF-based PAMAM composite
electrodes are excellent potential candidates for
application in direct methanol fuel cells.
Photocatalytic reduction of carbon dioxide to methanol using a ruthenium trin...Pawan Kumar
This document summarizes the photocatalytic reduction of carbon dioxide to methanol using a ruthenium trinuclear polyazine complex immobilized on graphene oxide under visible light irradiation. Specifically:
- A ruthenium complex was synthesized and immobilized on graphene oxide through complexation. This developed photocatalyst was used to reduce CO2 to methanol under visible light irradiation.
- After 48 hours of illumination, the yield of methanol was 3977.57 mmol/gcat, higher than for graphene oxide alone. The catalyst could be reused without loss of activity.
- Characterization showed the ruthenium complex was successfully immobilized on the graphene oxide support, enhancing its photocatalytic activity and enabling
The document describes using reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize novel block copolymers containing both a polyolefin block and a poly(styrene-co-maleic anhydride) block. Specifically, it details:
1) Using a commercially available polyolefin (Kraton L-1203) modified with a dithioester group to serve as a macroinitiator for RAFT polymerization and form the polyolefin block.
2) Conducting RAFT polymerizations of styrene and styrene-co-maleic anhydride using this macroinitiator and a small molecule RAFT agent to form the second block and yield polyolefin
This document summarizes a study investigating the initialization behavior of reversible addition-fragmentation chain transfer (RAFT)-mediated styrene-maleic anhydride copolymerizations using in situ 1H NMR spectroscopy. The results indicate specificity of addition of the RAFT agent leaving groups for either styrene or maleic anhydride. Analysis of the NMR spectra also showed that monomers are added individually, favoring the penultimate unit model of polymer propagation over other proposed mechanisms. Stereoselectivity was observed during monomer addition to the RAFT agent.
Highly stable pt ru nanoparticles supported on three-dimensional cubic ordere...suresh899
The cost of the catalysts used in the direct methanol fuel cell
poses a challenge to its widespread use as an energy efficient and environment
friendly fuel conversion technology. In this study, two types of highly ordered
mesoporous carbon CMK-8 (I and II) with high surface area and 3-D
bicontinuous interpenetrating channels were synthesized and deposited with
PtRu nanoparticles using the sodium borohydride reduction method. The
electrocatalytic capabilities for methanol oxidation were investigated using
cyclic voltammetry and chronoamperometry, and the results were compared
with that of PtRu deposited on Vulcan XC-72 using the same preparation
method as well as with commercial PtRu/C (E-TEK) catalyst. Pt Ru/CMK-8-I synthesized by the method developed in this work revealed an
outstanding specific mass activity (487.9 mA/mg) and superior stability
compared with the other supports, thus substantiating its potential to reduce
the costs of DMFC catalysts.
Functionalization of Diazomethyl Aromatic Compounds onto Single Wall Carbon N...drboon
One of the most fascinating and remarkable formulas existing in mathematics is the Euler Formula. It was formulated in 1740, constituting the main factor to reason why humankind can advance in science and mathematics. Accordingly, this research will continue investigating the potentiality of the Euler Formula or "the magical number e." The goal of the present study is to further assess the Euler formula and several of its applications such as the compound interest problem, complex numbers, trigonometry, signals (electrical engineering), and Ordinary Differential Equations. To accomplish this goal, the Euler Formula will be entered into the MATLAB software to obtain several plots representing the above applications. The importance of this study in mathematics and engineering will be discussed, and a case study on a polluted lake will be formulated.
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
This document describes the synthesis and characterization of a novel carbon nitride framework called C3N5. C3N5 has a 3:5 carbon to nitrogen stoichiometry and is synthesized by thermal deammoniation of melem hydrazine. Characterization reveals that in the C3N5 polymer, two s-heptazine units are bridged together with an azo linkage. This azo linkage extends the π-conjugated network and lowers the electronic bandgap to 1.76 eV compared to 2.7 eV for g-C3N4. Due to its lower bandgap and electron-rich character, C3N5 shows improved performance for applications in solar cells, photocatalysis
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction
Polyamidoamine (PAMAM) dendrimers has
been anchored on functionalized carbon nanofibers (CNF)
and supported Pt–Ru nanoparticles have been prepared with
NaBH4 as a reducing agent. The samples were characterized
by X-ray diffraction, scanning electron microscopy,
and transmission electron microscopy (TEM) analysis. It
was shown that Pt–Ru particles with small average size
(2.6 nm) were uniformly dispersed on PAMAM/CNF
composite support and displayed the characteristic diffraction
peaks of Pt face-centered cubic structure. The electrocatalytic
activities of the prepared-composites (20% Pt–Ru/PAMAMCNF)
were examined by using cyclic voltammetry for
oxidation of methanol. The electrocatalytic activity of the
CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode
for methanol oxidation showed better performance than that
of commercially available Johnson Mathey 20% Pt–Ru/C
catalyst. The results imply that CNF-based PAMAM composite
electrodes are excellent potential candidates for
application in direct methanol fuel cells.
Photocatalytic reduction of carbon dioxide to methanol using a ruthenium trin...Pawan Kumar
This document summarizes the photocatalytic reduction of carbon dioxide to methanol using a ruthenium trinuclear polyazine complex immobilized on graphene oxide under visible light irradiation. Specifically:
- A ruthenium complex was synthesized and immobilized on graphene oxide through complexation. This developed photocatalyst was used to reduce CO2 to methanol under visible light irradiation.
- After 48 hours of illumination, the yield of methanol was 3977.57 mmol/gcat, higher than for graphene oxide alone. The catalyst could be reused without loss of activity.
- Characterization showed the ruthenium complex was successfully immobilized on the graphene oxide support, enhancing its photocatalytic activity and enabling
The document describes using reversible addition-fragmentation chain transfer (RAFT) polymerization to synthesize novel block copolymers containing both a polyolefin block and a poly(styrene-co-maleic anhydride) block. Specifically, it details:
1) Using a commercially available polyolefin (Kraton L-1203) modified with a dithioester group to serve as a macroinitiator for RAFT polymerization and form the polyolefin block.
2) Conducting RAFT polymerizations of styrene and styrene-co-maleic anhydride using this macroinitiator and a small molecule RAFT agent to form the second block and yield polyolefin
This document summarizes a study investigating the initialization behavior of reversible addition-fragmentation chain transfer (RAFT)-mediated styrene-maleic anhydride copolymerizations using in situ 1H NMR spectroscopy. The results indicate specificity of addition of the RAFT agent leaving groups for either styrene or maleic anhydride. Analysis of the NMR spectra also showed that monomers are added individually, favoring the penultimate unit model of polymer propagation over other proposed mechanisms. Stereoselectivity was observed during monomer addition to the RAFT agent.
Highly stable pt ru nanoparticles supported on three-dimensional cubic ordere...suresh899
The cost of the catalysts used in the direct methanol fuel cell
poses a challenge to its widespread use as an energy efficient and environment
friendly fuel conversion technology. In this study, two types of highly ordered
mesoporous carbon CMK-8 (I and II) with high surface area and 3-D
bicontinuous interpenetrating channels were synthesized and deposited with
PtRu nanoparticles using the sodium borohydride reduction method. The
electrocatalytic capabilities for methanol oxidation were investigated using
cyclic voltammetry and chronoamperometry, and the results were compared
with that of PtRu deposited on Vulcan XC-72 using the same preparation
method as well as with commercial PtRu/C (E-TEK) catalyst. Pt Ru/CMK-8-I synthesized by the method developed in this work revealed an
outstanding specific mass activity (487.9 mA/mg) and superior stability
compared with the other supports, thus substantiating its potential to reduce
the costs of DMFC catalysts.
Functionalization of Diazomethyl Aromatic Compounds onto Single Wall Carbon N...drboon
One of the most fascinating and remarkable formulas existing in mathematics is the Euler Formula. It was formulated in 1740, constituting the main factor to reason why humankind can advance in science and mathematics. Accordingly, this research will continue investigating the potentiality of the Euler Formula or "the magical number e." The goal of the present study is to further assess the Euler formula and several of its applications such as the compound interest problem, complex numbers, trigonometry, signals (electrical engineering), and Ordinary Differential Equations. To accomplish this goal, the Euler Formula will be entered into the MATLAB software to obtain several plots representing the above applications. The importance of this study in mathematics and engineering will be discussed, and a case study on a polluted lake will be formulated.
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
This document describes the synthesis and characterization of a novel carbon nitride framework called C3N5. C3N5 has a 3:5 carbon to nitrogen stoichiometry and is synthesized by thermal deammoniation of melem hydrazine. Characterization reveals that in the C3N5 polymer, two s-heptazine units are bridged together with an azo linkage. This azo linkage extends the π-conjugated network and lowers the electronic bandgap to 1.76 eV compared to 2.7 eV for g-C3N4. Due to its lower bandgap and electron-rich character, C3N5 shows improved performance for applications in solar cells, photocatalysis
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction
The document describes a study of tetraphenylethene-triphenylamine (TPE-TPA) oligomers and a polymer. A series of oligomers (DATE, DTAE, DTDAE) and a polymer (PTAE) were synthesized using McMurry coupling and other reactions. All molecules showed aggregation-induced emission (AIE), emitting strongly in the solid state but very weakly in solution. Emission wavelengths and quantum yields varied with molecular structure, peaking for the largest oligomer DTDAE. The polymer had lower solubility and broader NMR peaks due to its large size. This work achieved both efficient solid-state emission and hole transport capability by combining TPE and TPA mo
Literature Seminar on Expansion of Pd chains through Beta-Carotene & Tetrapho...Nina Saraei
The document summarizes two papers on the expansion of palladium chains using β-carotene and tetraphosphine ligands. The first paper discusses the stepwise expansion of homonuclear and heteronuclear palladium chains from binuclear Pd(I) complexes supported by tetraphosphine ligands. Characterization data showed the complexes adopt linear structures with reversible metalation/demetalation. The second paper examines a bis-β-carotene ligand's ability to bind decanuclear palladium and palladium-platinum complexes into infinite π-stacked columns. Both papers demonstrate the use of multidentate ligands to control the assembly of extended metal atom chains.
The document summarizes the preparation and characterization of a novel luminescent terbium inorganic/organic hybrid material. 4-tert-butylbenzoic acid was modified with 3-aminopropyl trimethoxysilane to create a ligand (TBBA-APMS) that can both coordinate with terbium ions and undergo a sol-gel reaction with TEOS. This resulted in a hybrid material (Tb-TBBA-APMS) with bonds between Tb-O and Si-O. Characterization with UV-Vis, fluorescence and phosphorescence spectroscopy confirmed energy transfer between the ligand and terbium, producing strong terbium luminescence.
This document describes the synthesis and characterization of conductive polyimide/carbon composites with platinum surface deposits. Specifically, it discusses optimizing the conductivity of polyimide/carbon composites by varying the solvent composition, electrodepositing platinum onto the composite via cyclic voltammetry, and characterizing the material properties and electrochemical reactivity of the resulting polyimide/carbon/platinum composites.
This document summarizes research on the copolymerization of ε-caprolactam and L-lactide monomers to produce poly(ester-amide) copolymers. Two organocatalysts were tested: 1-(4-sulfobutyl)−3-methylimidazolium hydrogen sulphate (BAIL) and P4-t-Bu phosphazene superbase (P4). BAIL more effectively catalyzed the ring-opening polymerization of L-lactide, while P4 worked better for ε-caprolactam. The copolymers were characterized using FTIR, NMR, and conversion measurements to analyze composition and structure.
Polyaniline (PANI) Metal Oxide Nano Composites as a Conducting MaterialRSIS International
The combination of conducting nanoparticles and conducting polymers is a new area of research. The conducting polymer nanocomposites have both advantages of low dimensional systems and organic conductors. With this nanofibre morphology, the dispersibility and processibility of polyanilines can be improved.
The aim of this literature is to provide a survey of previous findings of researchers related to metal oxide nanocomposite polyaniline. In this paper we reviewed the properties, methods of synthesis, and various applications.
Maiyalagan,Electrochemical oxidation of methanol on pt v2 o5–c composite cata...kutty79
Platinum nanoparticles have been supported on V2O5–C composite through the reduction of chloroplatinic
acid with formaldehyde. The catalyst was characterized by X-ray diffraction and transmission electron
microscopy. Catalytic activity and stability for the oxidation of methanol were studied by using
cyclic voltammetry and chronoamperometry. Pt/V2O5–C composite anode catalyst on glassy carbon electrode
show higher electro-catalytic activity for the oxidation of methanol. High electro-catalytic activities
and good stabilities could be attributed to the synergistic effect between Pt and V2O5, avoiding the electrodes
being poisoned.
Nickel Decorated on Phosphorous-Doped Carbon Nitride as an Efficient Photocat...Pawan Kumar
Nickel nanoparticle-decorated phosphorous-doped graphitic carbon nitride (Ni@g-PC3N4)
was synthesized and used as an efficient photoactive catalyst for the reduction of various
nitrobenzenes under visible light irradiation. Hydrazine monohydrate was used as the source
of protons and electrons for the intended reaction. The developed photocatalyst was found to be
highly active and afforded excellent product yields under mild experimental conditions. In addition,
the photocatalyst could easily be recovered and reused for several runs without any detectable
leaching during the reaction.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...sunitha81
Poly (o-phenylenediamine) (PoPD) microrods were obtained by interfacial
polymerization using ferric chloride as oxidant and without any template or
functional dopant. Pt/PoPD nanocatalysts were prepared by the reduction of chloroplatinic
acid with sodium borohydride, and the composite catalysts formed were
characterized by X-ray diffraction and electrochemical methods. The nanocomposite
of Pt/PoPD microrods has been explored for their electro-catalytic performance
towards oxidation of methanol. The electro-catalytic activity of Pt/PoPD was
found to be much higher (current density 1.96 mA/cm2 at 0.70 V) in comparison to
Pt/Vulcan electrodes (the current density values of 1.56 mA/cm2 at 0.71 V) which
may be attributed to the microrod morphology of PoPD that facilitate the effective
dispersion of Pt particles and easier access of methanol towards the catalytic sites.
Chemical and electrochem method of synthesis of polyaniline and polythiophene...Mugilan Narayanasamy
This document summarizes chemical and electrochemical methods for synthesizing polyaniline and polythiophene. Polyaniline can exist in three oxidation states - leucoemeraldine, emeraldine, and pernigraniline. It can be synthesized chemically using an oxidative process with an acid and oxidizing agent like ammonium persulfate or potassium dichromate. Electrochemical synthesis grows a polyaniline film on an anode. Polythiophene is also synthesized chemically using oxidative polymerization with catalysts or electrochemically by applying a potential to drive polymerization. The McCullough and Rieke methods can produce regioregular polythiophene using nickel or palladium catalysts. Both polymers find applications in
Synthesis and properties of PolyanilineAwad Albalwi
This document summarizes the synthesis and properties of polyaniline. Polyaniline was prepared through chemical and electrochemical polymerization in acidic medium. Different solvents, including DMF and m-cresol, were compared for their effect on polyaniline's conductivity. UV-vis spectroscopy and cyclic voltammetry were used to analyze the polymer films. The conductivity of polyaniline was influenced by acidity and the electronic structure of different solvents, which impacts the polymer chain conformation. Polyaniline in m-cresol had higher conductivity than in DMF due to stronger interactions between adjacent polarons.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Highly stable pt–ru nanoparticles supported on three dimensional cubic ordere...tshankar20134
This document describes the synthesis and characterization of Pt-Ru nanoparticles supported on cubic ordered mesoporous carbon (Pt-Ru/CMK-8) and their evaluation as electrocatalysts for methanol oxidation in direct methanol fuel cells. Two types of CMK-8 carbon with different pore sizes were synthesized using two different mesoporous silica templates. Pt-Ru was deposited on the CMK-8 using sodium borohydride reduction. Characterization showed the CMK-8 had high surface areas over 1000 m2/g and pore volumes over 1.26 cm3/g. Electrochemical testing found the Pt-Ru/CMK-8-I catalyst had a high specific mass activity of 487
Synthesis, characterization and electrocatalytic activity of silver nanorods ...tshankar20134
This document describes the synthesis of silver nanorods using a polyol process. Silver nitrate and polyvinylpyrrolidone (PVP) are reduced by propylene glycol at high temperature, allowing control over the diameter and length of the nanorods. Characterization with SEM, TEM, XRD and UV-vis spectroscopy confirms the formation of crystalline silver nanorods. Electrochemical testing shows that a glassy carbon electrode coated with silver nanorods exhibits high catalytic activity for the reduction of benzyl chloride, with a more positive reduction potential than bulk silver or plain glassy carbon electrodes. The extraordinary catalytic effect of the silver nanorods is likely due to their morphology and high affinity for chloride ions.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenetshankar20134
This document summarizes research on V-Mn-MCM-41 catalysts for the vapor phase oxidation of o-xylene. Mesoporous monometallic and bimetallic catalysts with varying ratios of vanadium and manganese were synthesized and characterized. Their activity for oxidizing o-xylene to phthalic anhydride was measured and found to correlate with their physical and chemical properties. The V-MCM-41 catalyst with a Si/V ratio of 50 exhibited the highest activity and selectivity. Vanadium species in the +5 oxidation state within the MCM-41 silica matrix were determined to be the active sites for selectively forming phthalic anhydride.
Nanostructured fe2 o3 platform for the electrochemical sensing of folic acidtshankar20134
The document describes the synthesis of alpha-iron oxide (α-Fe2O3) nanofibers using a simple electrospinning method and their application for the electrochemical sensing of folic acid (FA). The α-Fe2O3 nanofiber-modified glassy carbon electrode showed good selectivity for detecting FA even in the presence of ascorbic acid, achieving a detection limit of 60 nM for FA. The α-Fe2O3 nanofibers provided a high surface area platform and enhanced the oxidation current and separation of voltammetric signals for FA and ascorbic acid compared to an unmodified electrode. The modified electrode was successfully used to determine FA concentrations in human blood serum samples.
Double layer energy storage in graphene a studytshankar20134
This document summarizes research on using graphene for energy storage in electrochemical double layer capacitors (EDLCs). Graphene has potential as an EDLC electrode material due to its high surface area and electrical conductivity. Studies have found specific capacitances of graphene electrodes ranging from tens of F/g to over 1000 F/g depending on preparation methods and electrolytes. However, graphene sheets tend to restack reducing surface area availability. Methods to prevent restacking like adding metal oxides or curving graphene sheets have improved capacitance. Research is optimizing graphene properties and composites to enhance energy and power densities for applications requiring high power such as filtering alternating current.
Fabrication, morphology and structural characterization of tungsten oxide nan...tshankar20134
The document describes a method for synthesizing tungsten oxide nanorods. Phosphotungstic acid is infiltrated into an alumina membrane template and then calcined to form WO3 nanorods inside the template. The nanorods are characterized using SEM, TEM, AFM, XRD, Raman and IR spectroscopy. SEM and TEM images show the nanorods have a diameter of around 200nm, matching the pore size of the template. XRD and Raman patterns confirm the nanorods have a monoclinic crystalline structure. The nanorods also show superior electrochemical cycling ability compared to bulk WO3 materials.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...tshankar20134
This document summarizes research on developing a nanocomposite catalyst of Pt supported on poly(o-phenylenediamine) (PoPD) microrods for electro-oxidation of methanol in fuel cells. PoPD microrods were synthesized through an interfacial polymerization method using ferric chloride. Pt nanoparticles were deposited on the PoPD microrods using sodium borohydride reduction of chloroplatinic acid. Characterization with XRD showed the Pt had a face-centered cubic structure. Electrochemical tests found the Pt/PoPD catalyst had higher catalytic activity and stability for methanol oxidation compared to a Pt/carbon catalyst, which may be due to the microrod morphology facilitating better
Nitrogen review on recent progress in nitrogen-doped graphene synthesis, cha...tshankar20134
This document reviews recent progress in nitrogen-doped graphene. It discusses various synthesis methods for nitrogen-doped graphene including chemical vapor deposition, segregation growth, solvothermal synthesis, and arc discharge. It describes common nitrogen bonding configurations in nitrogen-doped graphene of pyridinic nitrogen, pyrrolic nitrogen, and graphitic nitrogen. The document also reviews potential applications of nitrogen-doped graphene in areas like electrocatalysis, field-effect transistors, and energy storage based on experimental and theoretical studies.
Deposition of ni ti n coatings by a plasma assisted mocvd using an organometa...tshankar20134
Titanium nitride (TiN)/nickel (Ni) composite coatings were synthesized by plasma assisted metal-organic
chemical vapour deposition (PAMOCVD) using organo-metallic and metal-organic complexes namely dichlorobis(5-
cyclopentadienyl)titanium (IV) for titanium and N,N'-ethylene-bis(2,4-pentanedion-iminoato)nickel(II) for nickel. The
growth of such films was investigated in nitrogen (N2) plasma environment in the substrate temperature range of 450-
550ºC at a deposition pressure of 0.5-1 mbar. Prior to the deposition of films, the Ti precursor was subjected to the
equilibrium vapour pressure measurements by employing TG/DTA in transpiration mode, which led to the value of 109.2
± 5.6 kJ mol-1 for the standard enthalpy of sublimation (Ho
sub). The phase identification using glancing incidence x-ray
diffraction showed Ni/TiN is a nanocomposite coating containing nanocrystals of Ni and TiN with face centered cubic
structure. Scanning electron microscopy revealed a uniform surface morphology of the films, while chemical analysis by
energy dispersive analysis confirmed the presence of titanium, nickel and nitrogen in the composite films.
The document describes a study of tetraphenylethene-triphenylamine (TPE-TPA) oligomers and a polymer. A series of oligomers (DATE, DTAE, DTDAE) and a polymer (PTAE) were synthesized using McMurry coupling and other reactions. All molecules showed aggregation-induced emission (AIE), emitting strongly in the solid state but very weakly in solution. Emission wavelengths and quantum yields varied with molecular structure, peaking for the largest oligomer DTDAE. The polymer had lower solubility and broader NMR peaks due to its large size. This work achieved both efficient solid-state emission and hole transport capability by combining TPE and TPA mo
Literature Seminar on Expansion of Pd chains through Beta-Carotene & Tetrapho...Nina Saraei
The document summarizes two papers on the expansion of palladium chains using β-carotene and tetraphosphine ligands. The first paper discusses the stepwise expansion of homonuclear and heteronuclear palladium chains from binuclear Pd(I) complexes supported by tetraphosphine ligands. Characterization data showed the complexes adopt linear structures with reversible metalation/demetalation. The second paper examines a bis-β-carotene ligand's ability to bind decanuclear palladium and palladium-platinum complexes into infinite π-stacked columns. Both papers demonstrate the use of multidentate ligands to control the assembly of extended metal atom chains.
The document summarizes the preparation and characterization of a novel luminescent terbium inorganic/organic hybrid material. 4-tert-butylbenzoic acid was modified with 3-aminopropyl trimethoxysilane to create a ligand (TBBA-APMS) that can both coordinate with terbium ions and undergo a sol-gel reaction with TEOS. This resulted in a hybrid material (Tb-TBBA-APMS) with bonds between Tb-O and Si-O. Characterization with UV-Vis, fluorescence and phosphorescence spectroscopy confirmed energy transfer between the ligand and terbium, producing strong terbium luminescence.
This document describes the synthesis and characterization of conductive polyimide/carbon composites with platinum surface deposits. Specifically, it discusses optimizing the conductivity of polyimide/carbon composites by varying the solvent composition, electrodepositing platinum onto the composite via cyclic voltammetry, and characterizing the material properties and electrochemical reactivity of the resulting polyimide/carbon/platinum composites.
This document summarizes research on the copolymerization of ε-caprolactam and L-lactide monomers to produce poly(ester-amide) copolymers. Two organocatalysts were tested: 1-(4-sulfobutyl)−3-methylimidazolium hydrogen sulphate (BAIL) and P4-t-Bu phosphazene superbase (P4). BAIL more effectively catalyzed the ring-opening polymerization of L-lactide, while P4 worked better for ε-caprolactam. The copolymers were characterized using FTIR, NMR, and conversion measurements to analyze composition and structure.
Polyaniline (PANI) Metal Oxide Nano Composites as a Conducting MaterialRSIS International
The combination of conducting nanoparticles and conducting polymers is a new area of research. The conducting polymer nanocomposites have both advantages of low dimensional systems and organic conductors. With this nanofibre morphology, the dispersibility and processibility of polyanilines can be improved.
The aim of this literature is to provide a survey of previous findings of researchers related to metal oxide nanocomposite polyaniline. In this paper we reviewed the properties, methods of synthesis, and various applications.
Maiyalagan,Electrochemical oxidation of methanol on pt v2 o5–c composite cata...kutty79
Platinum nanoparticles have been supported on V2O5–C composite through the reduction of chloroplatinic
acid with formaldehyde. The catalyst was characterized by X-ray diffraction and transmission electron
microscopy. Catalytic activity and stability for the oxidation of methanol were studied by using
cyclic voltammetry and chronoamperometry. Pt/V2O5–C composite anode catalyst on glassy carbon electrode
show higher electro-catalytic activity for the oxidation of methanol. High electro-catalytic activities
and good stabilities could be attributed to the synergistic effect between Pt and V2O5, avoiding the electrodes
being poisoned.
Nickel Decorated on Phosphorous-Doped Carbon Nitride as an Efficient Photocat...Pawan Kumar
Nickel nanoparticle-decorated phosphorous-doped graphitic carbon nitride (Ni@g-PC3N4)
was synthesized and used as an efficient photoactive catalyst for the reduction of various
nitrobenzenes under visible light irradiation. Hydrazine monohydrate was used as the source
of protons and electrons for the intended reaction. The developed photocatalyst was found to be
highly active and afforded excellent product yields under mild experimental conditions. In addition,
the photocatalyst could easily be recovered and reused for several runs without any detectable
leaching during the reaction.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...sunitha81
Poly (o-phenylenediamine) (PoPD) microrods were obtained by interfacial
polymerization using ferric chloride as oxidant and without any template or
functional dopant. Pt/PoPD nanocatalysts were prepared by the reduction of chloroplatinic
acid with sodium borohydride, and the composite catalysts formed were
characterized by X-ray diffraction and electrochemical methods. The nanocomposite
of Pt/PoPD microrods has been explored for their electro-catalytic performance
towards oxidation of methanol. The electro-catalytic activity of Pt/PoPD was
found to be much higher (current density 1.96 mA/cm2 at 0.70 V) in comparison to
Pt/Vulcan electrodes (the current density values of 1.56 mA/cm2 at 0.71 V) which
may be attributed to the microrod morphology of PoPD that facilitate the effective
dispersion of Pt particles and easier access of methanol towards the catalytic sites.
Chemical and electrochem method of synthesis of polyaniline and polythiophene...Mugilan Narayanasamy
This document summarizes chemical and electrochemical methods for synthesizing polyaniline and polythiophene. Polyaniline can exist in three oxidation states - leucoemeraldine, emeraldine, and pernigraniline. It can be synthesized chemically using an oxidative process with an acid and oxidizing agent like ammonium persulfate or potassium dichromate. Electrochemical synthesis grows a polyaniline film on an anode. Polythiophene is also synthesized chemically using oxidative polymerization with catalysts or electrochemically by applying a potential to drive polymerization. The McCullough and Rieke methods can produce regioregular polythiophene using nickel or palladium catalysts. Both polymers find applications in
Synthesis and properties of PolyanilineAwad Albalwi
This document summarizes the synthesis and properties of polyaniline. Polyaniline was prepared through chemical and electrochemical polymerization in acidic medium. Different solvents, including DMF and m-cresol, were compared for their effect on polyaniline's conductivity. UV-vis spectroscopy and cyclic voltammetry were used to analyze the polymer films. The conductivity of polyaniline was influenced by acidity and the electronic structure of different solvents, which impacts the polymer chain conformation. Polyaniline in m-cresol had higher conductivity than in DMF due to stronger interactions between adjacent polarons.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Highly stable pt–ru nanoparticles supported on three dimensional cubic ordere...tshankar20134
This document describes the synthesis and characterization of Pt-Ru nanoparticles supported on cubic ordered mesoporous carbon (Pt-Ru/CMK-8) and their evaluation as electrocatalysts for methanol oxidation in direct methanol fuel cells. Two types of CMK-8 carbon with different pore sizes were synthesized using two different mesoporous silica templates. Pt-Ru was deposited on the CMK-8 using sodium borohydride reduction. Characterization showed the CMK-8 had high surface areas over 1000 m2/g and pore volumes over 1.26 cm3/g. Electrochemical testing found the Pt-Ru/CMK-8-I catalyst had a high specific mass activity of 487
Synthesis, characterization and electrocatalytic activity of silver nanorods ...tshankar20134
This document describes the synthesis of silver nanorods using a polyol process. Silver nitrate and polyvinylpyrrolidone (PVP) are reduced by propylene glycol at high temperature, allowing control over the diameter and length of the nanorods. Characterization with SEM, TEM, XRD and UV-vis spectroscopy confirms the formation of crystalline silver nanorods. Electrochemical testing shows that a glassy carbon electrode coated with silver nanorods exhibits high catalytic activity for the reduction of benzyl chloride, with a more positive reduction potential than bulk silver or plain glassy carbon electrodes. The extraordinary catalytic effect of the silver nanorods is likely due to their morphology and high affinity for chloride ions.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenetshankar20134
This document summarizes research on V-Mn-MCM-41 catalysts for the vapor phase oxidation of o-xylene. Mesoporous monometallic and bimetallic catalysts with varying ratios of vanadium and manganese were synthesized and characterized. Their activity for oxidizing o-xylene to phthalic anhydride was measured and found to correlate with their physical and chemical properties. The V-MCM-41 catalyst with a Si/V ratio of 50 exhibited the highest activity and selectivity. Vanadium species in the +5 oxidation state within the MCM-41 silica matrix were determined to be the active sites for selectively forming phthalic anhydride.
Nanostructured fe2 o3 platform for the electrochemical sensing of folic acidtshankar20134
The document describes the synthesis of alpha-iron oxide (α-Fe2O3) nanofibers using a simple electrospinning method and their application for the electrochemical sensing of folic acid (FA). The α-Fe2O3 nanofiber-modified glassy carbon electrode showed good selectivity for detecting FA even in the presence of ascorbic acid, achieving a detection limit of 60 nM for FA. The α-Fe2O3 nanofibers provided a high surface area platform and enhanced the oxidation current and separation of voltammetric signals for FA and ascorbic acid compared to an unmodified electrode. The modified electrode was successfully used to determine FA concentrations in human blood serum samples.
Double layer energy storage in graphene a studytshankar20134
This document summarizes research on using graphene for energy storage in electrochemical double layer capacitors (EDLCs). Graphene has potential as an EDLC electrode material due to its high surface area and electrical conductivity. Studies have found specific capacitances of graphene electrodes ranging from tens of F/g to over 1000 F/g depending on preparation methods and electrolytes. However, graphene sheets tend to restack reducing surface area availability. Methods to prevent restacking like adding metal oxides or curving graphene sheets have improved capacitance. Research is optimizing graphene properties and composites to enhance energy and power densities for applications requiring high power such as filtering alternating current.
Fabrication, morphology and structural characterization of tungsten oxide nan...tshankar20134
The document describes a method for synthesizing tungsten oxide nanorods. Phosphotungstic acid is infiltrated into an alumina membrane template and then calcined to form WO3 nanorods inside the template. The nanorods are characterized using SEM, TEM, AFM, XRD, Raman and IR spectroscopy. SEM and TEM images show the nanorods have a diameter of around 200nm, matching the pore size of the template. XRD and Raman patterns confirm the nanorods have a monoclinic crystalline structure. The nanorods also show superior electrochemical cycling ability compared to bulk WO3 materials.
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...tshankar20134
This document summarizes research on developing a nanocomposite catalyst of Pt supported on poly(o-phenylenediamine) (PoPD) microrods for electro-oxidation of methanol in fuel cells. PoPD microrods were synthesized through an interfacial polymerization method using ferric chloride. Pt nanoparticles were deposited on the PoPD microrods using sodium borohydride reduction of chloroplatinic acid. Characterization with XRD showed the Pt had a face-centered cubic structure. Electrochemical tests found the Pt/PoPD catalyst had higher catalytic activity and stability for methanol oxidation compared to a Pt/carbon catalyst, which may be due to the microrod morphology facilitating better
Nitrogen review on recent progress in nitrogen-doped graphene synthesis, cha...tshankar20134
This document reviews recent progress in nitrogen-doped graphene. It discusses various synthesis methods for nitrogen-doped graphene including chemical vapor deposition, segregation growth, solvothermal synthesis, and arc discharge. It describes common nitrogen bonding configurations in nitrogen-doped graphene of pyridinic nitrogen, pyrrolic nitrogen, and graphitic nitrogen. The document also reviews potential applications of nitrogen-doped graphene in areas like electrocatalysis, field-effect transistors, and energy storage based on experimental and theoretical studies.
Deposition of ni ti n coatings by a plasma assisted mocvd using an organometa...tshankar20134
Titanium nitride (TiN)/nickel (Ni) composite coatings were synthesized by plasma assisted metal-organic
chemical vapour deposition (PAMOCVD) using organo-metallic and metal-organic complexes namely dichlorobis(5-
cyclopentadienyl)titanium (IV) for titanium and N,N'-ethylene-bis(2,4-pentanedion-iminoato)nickel(II) for nickel. The
growth of such films was investigated in nitrogen (N2) plasma environment in the substrate temperature range of 450-
550ºC at a deposition pressure of 0.5-1 mbar. Prior to the deposition of films, the Ti precursor was subjected to the
equilibrium vapour pressure measurements by employing TG/DTA in transpiration mode, which led to the value of 109.2
± 5.6 kJ mol-1 for the standard enthalpy of sublimation (Ho
sub). The phase identification using glancing incidence x-ray
diffraction showed Ni/TiN is a nanocomposite coating containing nanocrystals of Ni and TiN with face centered cubic
structure. Scanning electron microscopy revealed a uniform surface morphology of the films, while chemical analysis by
energy dispersive analysis confirmed the presence of titanium, nickel and nitrogen in the composite films.
Template synthesis and characterization of well aligned nitrogen containing c...tshankar20134
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
One pot synthesis of chain-like palladium nanocubes and their enhanced electr...tshankar20134
This document describes a one-pot synthesis of chain-like palladium nanocubes and their enhanced electrocatalytic activity. A simple aqueous approach is used to produce anisotropic cubic chain-like Pd nanostructures using the neurotransmitter 5-hydroxytryptamine. Scanning electron microscopy images show the nanocubes have sizes between 140-210 nm and form chain-like branched structures. Testing shows the cubic chain-like nanostructures have over 11 times greater electrocatalytic activity for oxidizing formic acid, methanol, and ethanol compared to spherical nanoparticles and commercial Pd/C catalysts. The enhanced performance makes them promising multipurpose catalysts for direct fuel cells.
Dynamic and equilibrium studies on the sorption of basic dyetshankar20134
This document summarizes a study on the adsorption of Basic Brown 4 dye onto multi-walled carbon nanotubes (MWNTs) prepared from renewable carbon precursors and commercial activated carbon. MWNTs were synthesized from pine oil, methyl ester of Jatropha curcas oil, and methyl ester of Pongamiya pinnata oil. Batch adsorption experiments were conducted to understand the effects of parameters like solution pH, contact time, temperature, and to evaluate adsorption kinetics and thermodynamics. Kinetic data fitted well to the pseudo-second order model. Adsorption was found to be spontaneous and endothermic in nature.
Electrodeposited pt on three dimensional interconnected graphene as a free st...tshankar20134
The document summarizes research on using a three-dimensional interconnected graphene structure as an electrode support for platinum nanoparticles for fuel cell applications. Key points:
1) Graphene was grown into a 3D foam-like structure using chemical vapor deposition on a nickel foam template, creating a seamless porous structure with high surface area and conductivity.
2) Platinum nanoparticles were deposited on the 3D graphene using pulsed electrodeposition, allowing control over particle size and uniform dispersion.
3) The 3D graphene with platinum nanoparticles showed improved catalytic activity for methanol oxidation compared to carbon fibers, due to the unique 3D structure, high surface area, and high conductivity of the graphene support.
Film pore diffusion modeling for sorption of azo dye on to exfoliated graphit...tshankar20134
This document summarizes a study on the adsorption of the azo dye Acid Orange 7 onto exfoliated graphitic nanoplatelets (xGnPs) as a potential adsorbent. The effects of temperature, initial dye concentration, and pH on the adsorption process were investigated. Kinetic models including pseudo-first order, pseudo-second order and Elovich equation were applied and the data fit best with the pseudo-second order model, indicating chemisorption. Equilibrium studies showed the adsorption data fit well with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity was found to increase with decreasing temperature, indicating an exothermic process.
This document describes the synthesis and characterization of Pt-Ru nanoparticles supported on a polyamidoamine (PAMAM) dendrimer functionalized carbon nanofiber (CNF) composite catalyst for use in direct methanol fuel cells. Pt-Ru nanoparticles with an average size of 2.6 nm were uniformly dispersed on the PAMAM/CNF support. X-ray diffraction and transmission electron microscopy showed the small, uniform nanoparticles with the characteristic face-centered cubic structure of Pt. Cyclic voltammetry demonstrated that the 20% Pt-Ru-PAMAM/CNF composite electrode exhibited better electrocatalytic activity for methanol oxidation compared to a commercially available 20% Pt-Ru/C catalyst.
Synthesis and electro catalytic activity of methanol oxidation on nitrogen co...Science Padayatchi
The document discusses the synthesis and electro-catalytic activity of methanol oxidation on nitrogen containing carbon nanotubes supported Pt electrodes. Specifically:
1. Various nitrogen containing carbon nanotubes were synthesized using different nitrogen containing polymers as templates.
2. The nitrogen content and morphology of the carbon nanotubes were characterized using electron microscopy.
3. The catalytic activity of Pt supported on nitrogen containing carbon nanotubes was evaluated for methanol oxidation and compared to Pt supported on regular carbon nanotubes and carbon black.
4. Preliminary results showed that nitrogen containing carbon nanotubes with 10.5% nitrogen content exhibited higher catalytic activity than other supports, likely due to additional active sites from nitrogen
Synthesis and electro catalytic activity of methanol oxidation on nitrogen co...Science Padayatchi
The document discusses the synthesis and electro-catalytic activity of methanol oxidation on nitrogen containing carbon nanotubes supported Pt electrodes. Specifically:
1. Various nitrogen containing carbon nanotubes were synthesized using different nitrogen containing polymers as templates.
2. The nitrogen content and morphology of the carbon nanotubes were characterized using electron microscopy.
3. The electro-catalytic activity of Pt particles supported on nitrogen containing carbon nanotubes was evaluated for methanol oxidation and compared to conventional carbon supports. Nitrogen containing carbon nanotube supported electrodes showed higher catalytic activity.
Maiyalagan, Synthesis and electro catalytic activity of methanol oxidation on...kutty79
Template synthesis of various nitrogen containing carbon nanotubes using different nitrogen containing polymers and the variation of nitrogen
content in carbon nanotube (CNT) on the behaviour of supported Pt electrodes in the anodic oxidation of methanol in direct methanol fuel cells was
investigated. Characterizations of the as-prepared catalysts are investigated by electron microscopy and electrochemical analysis. The catalyst with
N-containing CNT as a support exhibits a higher catalytic activity than that carbon supported platinum electrode and CNT supported electrodes.
The N-containing CNT supported electrodes with 10.5% nitrogen content show a higher catalytic activity compared to other N-CNT supported
electrodes. This could be due to the existence of additional active sites on the surface of the N-containing CNT supported electrodes, which favours
better dispersion of Pt particles. Also, the strong metal-support interaction plays a major role in enhancing the catalytic activity for methanol
oxidation.
Final Report (Graphene supported platinum nanoparticles) (1)Sridharan Thirumalai
This document is a student project report on platinum-graphene nanocomposites as electrocatalysts in PEM fuel cells. It was submitted by T.V. Sridharan to Professor Manoj Neergat at the Indian Institute of Technology, Bombay under his supervision. The report describes the synthesis of Pt/rGO nanocomposites using a modified polyol method, and their physical and electrochemical characterization. TEM analysis showed the successful deposition of platinum nanoparticles on graphene oxide sheets. Electrochemical experiments found the Pt/rGO composite had a higher effective surface area than Pt/C, but similar activity for the oxygen reduction reaction. Further research is needed to fully realize graphene's potential as
Nitrogen containing carbon nanotubes as supports for pt – alternate anodes fo...Science Padayatchi
This document summarizes research on using nitrogen-containing carbon nanotubes as supports for platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells. Key points:
1. Nitrogen-containing carbon nanotubes were synthesized using an alumina membrane template and pyrolysis of polyvinylpyrrolidone polymer.
2. Platinum nanoparticles with an average size of 3 nm were uniformly dispersed on the nitrogen-containing carbon nanotubes via chemical reduction.
3. Electrochemical testing found the platinum catalyst supported on nitrogen-containing carbon nanotubes had over 10 times higher catalytic activity for methanol oxidation compared to a commercial platinum/carbon catalyst.
Nitrogen containing carbon nanotubes as supports for pt – alternate anodes fo...kutty79
This document summarizes research on using nitrogen-containing carbon nanotubes as supports for platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells. Key points:
1. Nitrogen-containing carbon nanotubes were synthesized using an alumina membrane template and pyrolysis of polyvinylpyrrolidone polymer.
2. Highly dispersed platinum nanoparticles around 3nm in size were uniformly deposited on the nitrogen-containing carbon nanotubes.
3. Electrochemical testing found the platinum catalyst supported on nitrogen-containing carbon nanotubes had over 10 times higher catalytic activity for methanol oxidation compared to a commercial platinum on carbon catalyst.
Nitrogen containing carbon nanotubes as supports for pt – alternate anodes fo...Science Padayatchi
This document summarizes research on using nitrogen-containing carbon nanotubes as supports for platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells. Key points:
1. Nitrogen-containing carbon nanotubes were synthesized using an alumina membrane template and pyrolysis of polyvinylpyrrolidone polymer.
2. Highly dispersed platinum nanoparticles around 3nm in size were uniformly deposited on the nitrogen-containing carbon nanotubes.
3. Electrochemical testing found the platinum catalyst supported on nitrogen-containing carbon nanotubes had over 10 times higher catalytic activity for methanol oxidation compared to a commercial platinum on carbon catalyst.
Nitrogen containing carbon nanotubes as supports fortshankar20134
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
3) Cyclic voltammetry studies showed that the platinum nanoparticles supported on nitrogen-containing carbon nanotubes had significantly higher catalytic activity for methanol oxidation compared to a commercial platinum on carbon catalyst.
Nitrogen containing carbon nanotubes as supports for pt–alternate anodes for ...tshankar20134
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
3) Cyclic voltammetry studies showed that the platinum nanoparticles supported on nitrogen-containing carbon nanotubes had higher catalytic activity for methanol oxidation compared to a conventional platinum on carbon black catalyst.
Nitrogen containing carbon nanotubes as supports for pt–alternate anodes for ...madlovescience
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotubes with an average particle size of 3 nm.
3) Cyclic voltammetry studies showed that the platinum nanoparticles supported on nitrogen-containing carbon nanotubes had significantly higher catalytic activity for methanol oxidation compared to a conventional platinum on carbon catalyst.
Nitrogen containing carbon nanotubes as supports formadlovescience
1) Nitrogen-containing carbon nanotubes were synthesized and used to support platinum nanoparticles as an alternative anode catalyst for direct methanol fuel cells.
2) The platinum nanoparticles were uniformly distributed on the nitrogen-containing carbon nanotube surface with an average particle size of 3 nm.
3) Cyclic voltammetry studies showed that the platinum nanoparticles supported on nitrogen-containing carbon nanotubes had higher catalytic activity for methanol oxidation compared to a conventional platinum on carbon black catalyst.
Synthesis and electro catalytic activity of methanol oxidation on nitrogen co...tshankar20134
The document summarizes research on synthesizing nitrogen-containing carbon nanotubes using different nitrogen-containing polymers as templates. Platinum particles were then supported on these nitrogen-containing carbon nanotubes and on regular carbon nanotubes and carbon for comparison. Characterization showed the nitrogen-containing carbon nanotube supported platinum catalyst had higher catalytic activity for methanol oxidation than the other catalysts. This was attributed to the existence of additional active sites on the nitrogen-containing carbon nanotube surface, which improved platinum particle dispersion and metal-support interaction.
Effects of heat treatment on the catalytic activity and methanol tolerance of...tshankar20134
This document studies the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Platinum (Pt), platinum-cobalt (Pt-Co), platinum-copper (Pt-Cu), platinum-iron (Pt-Fe), and platinum-nickel (Pt-Ni) catalysts were heat treated at different temperatures and their properties were analyzed. Heat treatment was found to increase particle size but also improved catalytic activity in most cases. The optimum heat treatment temperature depended on the specific catalyst. Pt-Cu/C and Pt-Fe/C catalysts heat treated at 350°C showed the highest oxygen reduction reaction activity and best methanol tolerance. Overall, Pt-
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...sunidevi
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity and stability via cyclic voltammetry. The catalyst prepared with a 2-hour reduction time showed higher mass activity and good stability over 100 cycles for methanol electrooxidation compared to other reduction times. The results indicate these catalysts prepared via a low-cost ethanol reduction method have potential as anode catalysts for direct methanol fuel cells.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...sunilove
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity via cyclic voltammetry. The key findings were:
1) Pt-Ru nanoparticles were successfully synthesized on carbon support using ethanol as a reducing agent without any stabilizers or heat treatment.
2) Characterization showed the catalysts had an FCC crystal structure and particle size around 3.7 nm.
3) Electrochemical testing found the catalyst reduced for 2 hours had the highest mass activity and stability for methanol electrooxidation over 100 cycles.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...Science Padayatchi
This document summarizes a study that prepared carbon-supported Pt-Ru nanocatalysts for methanol electrooxidation using a simple ethanol reduction method. The catalysts were characterized using various techniques and tested for their electrocatalytic activity and stability via cyclic voltammetry. The catalyst prepared with a 2-hour reduction time showed higher mass activity and good stability over 100 cycles for methanol electrooxidation compared to other reduction times. The results indicate these catalysts prepared via a low-cost ethanol reduction method have potential as anode catalysts for direct methanol fuel cells.
Highly active pd and pd–au nanoparticles supported on functionalized graphene...Science Padayatchi
Highly active Pd and Pd–Au nanoparticles supported on functionalized graphene nanoplatelets for enhanced formic acid oxidation
Similar to Pt ru nanoparticles-supported_pamam_dendrimer_functionalized_carbon_nanofiber_composite_catalysts_and_their_application_to_methanol_oxid (20)
Synthesis and optimisation of ir o2 electrocatalysts by adams fusion method f...tshankar20134
The document summarizes research into optimizing IrO2 as an electrocatalyst for oxygen evolution in solid polymer electrolyte electrolyzers. IrO2 was synthesized using the Adams fusion method, varying synthesis duration from 0.5-4 hours and temperature from 250-500°C. Characterization showed that increasing duration and temperature increased crystallinity and particle size. Electrochemical testing found that IrO2 synthesized for 2 hours at 350°C had the best catalytic activity for oxygen evolution, outperforming a commercial IrO2. Higher temperatures favored formation of the active IrO2 phase but also led to larger particle sizes which decreased activity. Lower than 350°C did not favor IrO2 formation.
The document summarizes research on nano-structured lanthanum (La)-doped zinc oxide (ZnO) prepared using a combustion method. Coral-shaped ZnO nanostructures with pore sizes of 10-50 nm were successfully synthesized. Transmission electron microscopy showed the coral shape and porous nature increased with higher La doping concentrations. X-ray diffraction analysis confirmed the wurtzite structure of pure and doped ZnO. Optical studies showed absorbance in the UV region decreased and band gap increased with higher La doping levels. Photoluminescence spectra exhibited La characteristic emission and a shift in emission with doping. The La-doped ZnO nanostructures showed potential for applications in chemical sensing,
Green synthesis of well dispersed nanoparticles using leaf extract of medicin...tshankar20134
Green synthesis of gold nanoparticles was achieved using an extract of the medicinal plant Adhatoda vasica.
The nanoparticles formed were predominantly spherical and monodisperse, with sizes ranging from 22 to 47 nm as determined through transmission electron microscopy analysis. Ultraviolet-visible spectroscopy and X-ray diffraction data confirmed the formation and crystalline nature of the gold nanoparticles. Functional groups present in the plant extract, such as hydroxyl and carboxyl groups, were found to play a role in both the reduction of gold ions and stabilization of the resulting nanoparticles. This green synthesis method using A. vasica extract could provide a means of producing biocompatible gold nanoparticles for applications such as drug delivery.
Equilibrium and kinetic studies on the adsorption of methylene blue from aqueoustshankar20134
The document summarizes a study on the adsorption of the dye methylene blue from aqueous solution using activated carbon prepared from Murraya koenigii stems. Some key findings:
1) The activated carbon was characterized and found to have a specific surface area of 508 m2/g and pore structure consisting of micro and mesopores suitable for adsorption.
2) Batch adsorption experiments showed that adsorption capacity increased with increasing adsorbent dosage, reaching 98.99% dye removal at 0.12g dosage.
3) Equilibrium data fitted well to Langmuir and Temkin isotherm models, indicating monolayer adsorption occurred with a maximum adsorption capacity of 123
Electro oxidation of methanol on ti o2 nanotube supported platinum electrodestshankar20134
This document summarizes research on using TiO2 nanotubes as a support for platinum nanoparticles for use as an electrocatalyst in methanol fuel cells. TiO2 nanotubes were synthesized using anodic aluminum oxide as a template. Platinum nanoparticles 3-4 nm in size were uniformly dispersed on the TiO2 nanotube supports. Electrochemical testing found that platinum nanoparticles supported on TiO2 nanotubes had higher catalytic activity for methanol oxidation compared to commercial Pt/C catalysts, with mass activity over 33 mA/mg Pt versus 3.25 mA/mg Pt for Pt/C. The improved activity is attributed to the TiO2 support preventing CO poisoning of platinum sites and possible electronic interactions between
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...tshankar20134
The document describes a study that prepared carbon-supported PtRu nanocatalysts using an ethanol reduction method for different reaction times. The catalysts were characterized using various techniques and tested for their electrocatalytic activity in methanol oxidation. XRD and TEM analysis showed the catalysts had an FCC structure with an average particle size of 3.7 nm. Cyclic voltammetry tests found that the catalyst prepared at a 2h reduction time had higher electrocatalytic activity and stability for methanol electrooxidation compared to the other catalysts. The results suggest these catalysts could be promising anode catalysts for direct methanol fuel cells.
This document summarizes research on developing Pt/V2O5-C composite catalysts for methanol oxidation in direct methanol fuel cells (DMFCs). Pt nanoparticles were dispersed on a V2O5-C composite support through chemical reduction. The catalyst was characterized using XRD and TEM, which showed the formation of small Pt nanoparticles (~3 nm) on the support. Electrochemical testing showed that the Pt/V2O5-C composite catalyst had higher catalytic activity for methanol oxidation compared to a commercial Pt/C catalyst, as indicated by a more positive onset potential and higher forward/reverse peak current ratios. The composite catalyst also demonstrated comparable stability during chronoamperometry testing. The improved performance is attributed to
Components of pem_fuel_cells_an_overviewtshankar20134
The document provides an overview of the key components of proton exchange membrane fuel cells (PEMFCs). PEMFCs consist of a membrane electrode assembly (MEA) with a proton-conducting membrane sandwiched between two electrode layers. Perfluorinated sulfonic acid membranes like Nafion are most widely used as they have high proton conductivity while preventing fuel/oxidant mixing. Efforts are ongoing to develop alternative membranes and electrocatalysts to reduce costs and improve durability in order to facilitate PEMFC commercialization for applications like transportation.
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
“An Outlook of the Ongoing and Future Relationship between Blockchain Technologies and Process-aware Information Systems.” Invited talk at the joint workshop on Blockchain for Information Systems (BC4IS) and Blockchain for Trusted Data Sharing (B4TDS), co-located with with the 36th International Conference on Advanced Information Systems Engineering (CAiSE), 3 June 2024, Limassol, Cyprus.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
Unlocking Productivity: Leveraging the Potential of Copilot in Microsoft 365, a presentation by Christoforos Vlachos, Senior Solutions Manager – Modern Workplace, Uni Systems
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
Cosa hanno in comune un mattoncino Lego e la backdoor XZ?Speck&Tech
ABSTRACT: A prima vista, un mattoncino Lego e la backdoor XZ potrebbero avere in comune il fatto di essere entrambi blocchi di costruzione, o dipendenze di progetti creativi e software. La realtà è che un mattoncino Lego e il caso della backdoor XZ hanno molto di più di tutto ciò in comune.
Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
AI 101: An Introduction to the Basics and Impact of Artificial IntelligenceIndexBug
Imagine a world where machines not only perform tasks but also learn, adapt, and make decisions. This is the promise of Artificial Intelligence (AI), a technology that's not just enhancing our lives but revolutionizing entire industries.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Unlock the Future of Search with MongoDB Atlas_ Vector Search Unleashed.pdfMalak Abu Hammad
Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
* What is Vector Search?
* Importance and benefits of vector search
* Practical use cases across various industries
* Step-by-step implementation guide
* Live demos with code snippets
* Enhancing LLM capabilities with vector search
* Best practices and optimization strategies
Perfect for developers, AI enthusiasts, and tech leaders. Learn how to leverage MongoDB Atlas to deliver highly relevant, context-aware search results, transforming your data retrieval process. Stay ahead in tech innovation and maximize the potential of your applications.
#MongoDB #VectorSearch #AI #SemanticSearch #TechInnovation #DataScience #LLM #MachineLearning #SearchTechnology
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/building-and-scaling-ai-applications-with-the-nx-ai-manager-a-presentation-from-network-optix/
Robin van Emden, Senior Director of Data Science at Network Optix, presents the “Building and Scaling AI Applications with the Nx AI Manager,” tutorial at the May 2024 Embedded Vision Summit.
In this presentation, van Emden covers the basics of scaling edge AI solutions using the Nx tool kit. He emphasizes the process of developing AI models and deploying them globally. He also showcases the conversion of AI models and the creation of effective edge AI pipelines, with a focus on pre-processing, model conversion, selecting the appropriate inference engine for the target hardware and post-processing.
van Emden shows how Nx can simplify the developer’s life and facilitate a rapid transition from concept to production-ready applications.He provides valuable insights into developing scalable and efficient edge AI solutions, with a strong focus on practical implementation.
Goodbye Windows 11: Make Way for Nitrux Linux 3.5.0!SOFTTECHHUB
As the digital landscape continually evolves, operating systems play a critical role in shaping user experiences and productivity. The launch of Nitrux Linux 3.5.0 marks a significant milestone, offering a robust alternative to traditional systems such as Windows 11. This article delves into the essence of Nitrux Linux 3.5.0, exploring its unique features, advantages, and how it stands as a compelling choice for both casual users and tech enthusiasts.
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
UiPath Test Automation using UiPath Test Suite series, part 6DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 6. In this session, we will cover Test Automation with generative AI and Open AI.
UiPath Test Automation with generative AI and Open AI webinar offers an in-depth exploration of leveraging cutting-edge technologies for test automation within the UiPath platform. Attendees will delve into the integration of generative AI, a test automation solution, with Open AI advanced natural language processing capabilities.
Throughout the session, participants will discover how this synergy empowers testers to automate repetitive tasks, enhance testing accuracy, and expedite the software testing life cycle. Topics covered include the seamless integration process, practical use cases, and the benefits of harnessing AI-driven automation for UiPath testing initiatives. By attending this webinar, testers, and automation professionals can gain valuable insights into harnessing the power of AI to optimize their test automation workflows within the UiPath ecosystem, ultimately driving efficiency and quality in software development processes.
What will you get from this session?
1. Insights into integrating generative AI.
2. Understanding how this integration enhances test automation within the UiPath platform
3. Practical demonstrations
4. Exploration of real-world use cases illustrating the benefits of AI-driven test automation for UiPath
Topics covered:
What is generative AI
Test Automation with generative AI and Open AI.
UiPath integration with generative AI
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
1. J Solid State Electrochem (2009) 13:1561–1566
DOI 10.1007/s10008-008-0730-0
ORIGINAL PAPER
Pt–Ru nanoparticles supported PAMAM dendrimer
functionalized carbon nanofiber composite catalysts
and their application to methanol oxidation
T. Maiyalagan
Received: 22 August 2008 / Revised: 6 October 2008 / Accepted: 4 November 2008 / Published online: 20 November 2008
# Springer-Verlag 2008
Abstract Polyamidoamine (PAMAM) dendrimers has
been anchored on functionalized carbon nanofibers (CNF)
and supported Pt–Ru nanoparticles have been prepared with
NaBH4 as a reducing agent. The samples were characterized by X-ray diffraction, scanning electron microscopy,
and transmission electron microscopy (TEM) analysis. It
was shown that Pt–Ru particles with small average size
(2.6 nm) were uniformly dispersed on PAMAM/CNF
composite support and displayed the characteristic diffraction
peaks of Pt face-centered cubic structure. The electrocatalytic
activities of the prepared-composites (20% Pt–Ru/PAMAMCNF) were examined by using cyclic voltammetry for
oxidation of methanol. The electrocatalytic activity of the
CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode
for methanol oxidation showed better performance than that
of commercially available Johnson Mathey 20% Pt–Ru/C
catalyst. The results imply that CNF-based PAMAM composite electrodes are excellent potential candidates for
application in direct methanol fuel cells.
Keywords Methanol oxidation . DMFC . Dendrimers .
Nanostructured materials . Electro-catalyst
Introduction
Fuel cells operate with the electrochemical oxidation of
hydrogen or methanol, as fuels at the anode and the
reduction of oxygen at the cathode are attractive power
T. Maiyalagan (*)
Department of Chemistry, School of Science and Humanities,
VIT University,
Vellore 632014, India
e-mail: maiyalagan@gmail.com
sources due to their high conversion efficiencies, low
pollution, light weight, and high power density. Methanol
offers the advantage of easy storage and transportation
when compared to hydrogen oxygen fuel cell, its energy
density (~2,000 Wh/kg) and operating cell voltage (0.4 V)
are lower than the theoretical energy density (~6,000 Wh/kg)
and the thermodynamic potential (~1.2 V) [1, 2]. However,
the fuel cells could not reach the stage of commercialization
due to the high cost, which is mainly associated with the
noble metal-loaded electrodes and the membrane. In order
to reduce the amount of Pt loading on the electrodes, there
have been considerable efforts to increase the dispersion of
the metal on the support. The catalyst is very often found to
disperse on a conventional carbon support, and the support
material influences the catalytic activity through metal
support interaction [3–5].
New novel carbon support materials such as graphite
nanofibers (GNFs) [6, 7], carbon nanotubes (CNT) [8–12],
carbon nanohorns [13], and carbon nanocoils [14] provide
alternate candidates of carbon support for fuel cell
applications. Bessel et al. [6] and Steigerwalt et al. [7]
used GNFs as supports for Pt and Pt–Ru alloy electrocatalysts. They have observed better activity for methanol
oxidation. The high electronic conductivity of GNF and the
specific crystallographic orientation of the metal particles
resulting from well-ordered GNF support are believed to be
the factors for the observed enhanced electro-catalytic
activity. In heterogeneous catalysis, one of the important
tasks is the determination of the number of active sites in
the catalyst. For a given catalyst, the number of active sites
present is responsible for the observed catalytic activity. A
considerable amount of research has been devoted toward
understanding the number of active sites and the role
played by the carrier of the supported catalysts. The most
efficient utilization of any supported catalyst depends on
2. 1562
the percentage of exposed or the dispersion of the active
component on the surface of the carrier material. Among
the various factors that influence the dispersion of an active
component, the nature of the support and the extent of the
active component loading are of considerable importance.
Without surface modification, most of the carbon nanomaterials lack sufficient binding sites for anchoring precursor
metal ions or metal nanoparticles, which usually lead to poor
dispersion and the aggregation of metal nanoparticles,
especially at high loading conditions. To introduce more
binding sites and surface anchoring groups, an acid oxidation
process was very frequently adopted to treat carbon nanomaterials in a mixed acid aqueous solution, which introduces
surface bound polar hydroxyl and carboxylic acid groups for
subsequent anchoring and reductive conversion of precursor
metal ions to metal nanoparticles [15].
Generally, metal nano-particles have been synthesized for
the purpose of increasing the catalytic surface area in
comparison to bulk metal and have utilized strategies such
as stabilization in a soluble polymer matrix or encapsulation
in dendrimers to protect them from aggregation. Dendrimers
are good candidates for preparing metal nanoparticles because
they can act as structurally and well-defined templates and
robust stabilizers. Polyamidoamine (PAMAM) dendrimers, in
particular, have been used as nanoreactors with effective
nanoparticle stabilization. In addition, encapsulated nanoparticles surfaces are accessible to substrates so that catalytic
reactions can be carried out [16–18].
PAMAM dendrimer encapsulated Pt nanoparticles and PtPd
bimetallic nanoaparticles are electrocatalytically active for
oxygen reduction [19–21]. Also dendrimer-encapsulated platinum nanoparticles supported on carbon fiber and nitrogendoped CNT as electrodes for oxygen reduction [22, 23].
In addition, platinum–ruthenium alloys are the best
catalysts for methanol oxidation direct methanol fuel cells
[24, 25]. PAMAM dendrimers were modified with a Nicyclam as novel electrocatalytic material for the electrochemical oxidation of methanol [26]. Kim et al. [27] have
reported the preparation of platinum–dendrimer hybrid
nanowires using alumina templates, which exhibited and
enhanced electro-catalytic activity toward methanol oxidation.
PAMAM dendrimer (PAMAM 4.5)-encapsulated Pt nanoparticles chemically linked to gold substrates through a
cystamine monolayer exhibited electrocatalytic activity toward
the oxidation of methanol [28].The terminal functional groups
of the dendrimers stabilizes metal nanoparticles without
aggregation. In this paper, we make use of the fourthgeneration amine-terminated PAMAM dendrimers (G4-NH2)
to anchor on the functionalized carbon nanofiber (CNF) as a
substrate and then encapsulate Pt–Ru nanoparticles on
dendrimers for the better dispersion of the electrode, which
exhibited very good catalytic activity. These materials are
characterized and studied, using X-ray diffraction (XRD),
J Solid State Electrochem (2009) 13:1561–1566
scanning electron microscopy (SEM), transmission electron
microscopy (TEM), and cyclic voltammetry. The electrochemical properties of the composite electrode (Pt–Ru–
PAMAM/CNF) were compared to those of the commercial
electrode (Pt–Ru/C), using cyclic voltammetry. The 20% Pt–
Ru–PAMAM/CNF exhibited excellent catalytic activity and
stability when compared to the 20 wt.% Pt–Ru/C.
Experimental
Materials
All the chemicals used are of analytical grade. CNFs (grade
PR 24 LHT) are commercially available from Pyrograf,
USA. 1-(3-Dimethyl-aminopropyl)-3-ethyl-carbodiimidehydrochloride (EDC), N-hydroxysuccinimide (NHS), hexachloroplatinic acid, and ruthenium (III) chloride hydrate are
procured from Sigma-Aldrich and used as received. Vulcan
XC-72 carbon black is purchased from Cabot. Methanol
and sulfuric acid are obtained from Fischer Chemicals.
Nafion 5 wt.% solution is obtained from Dupont and is
used as received. Fourth generation amine-terminated
polyamidoamine PAMAM dendrimers (G4-NH2) with the
highest available purity (10 wt.% in methanol) are obtained
from Aldrich and used without further purification.
Functionalization of CNF
The CNF is treated with mixed acid aqueous solution of
HNO3 and H2SO4 in 1:3 ratios under magnetic stirrer for
3 h. It is then washed with water and evaporated to dryness.
Preparation of CNF-PAMAM
Fifty milliliters of 0.1 mg/ml carboxylated CNF containing
100 mg of EDC and 100 mg of NHS is slowly added into a
methanol solution of 20% G4 PAMAM under high speed
agitating.
Preparation of Pt–Ru–PAMAM/CNF catalysts:
6.15 mM H2PtCl6 and 11.8mM RuCl3 and dendrimer
encapsulated CNF are mixed by keeping the solution under
magnetic stirrer for 3 h. Five milliliters of 0.1 M NaBH4 is
added to the solution and kept under evaporation. A
schematic of the detailed procedure for the electrocatalyst
preparation is shown in Fig. 1.
Characterization
The phases and lattice parameters of the catalyst are
characterized by XRD patterns employing Shimadzu XD-
3. J Solid State Electrochem (2009) 13:1561–1566
1563
Fig. 1 Schematic diagram
illustrating synthesis of Pt–Ru–
PAMAM/CNF
D1 diffractometer using Cu Kα radiation (λ=1.5418 Å)
operating at 40 kV and 48 mA. XRD samples are obtained
by depositing composite supported nanoparticles on a glass
slide and drying the latter in a vacuum overnight. The
scanning electron micrographs are obtained using JEOL
JSM-840 model, working at 15 keV. For TEM studies, the
composite dispersed in ethanol are placed on the copper
grid, and the images are obtained using JEOL JEM-3010
model, operating at 300 keV.
Electrochemical measurements
All electrochemical measurements are performed using a BAS
Epsilon potentiostat. A three-electrode cell is used, which
consisted of the glassy carbon (0.07 cm2) as working electrode
and Pt foil and Ag/AgCl (saturated by KCl solution)
electrodes as counter and reference electrodes, respectively,
are used. All the electrochemical experiments are carried out
at room temperature in 0.5 M H2SO4 electrolyte. The
electrolyte solution is purged with high pure nitrogen for
30 min prior to a series of voltammetric experiments.
centered cubic structure can be observed. X-ray scattering
from the CNF support is evidenced by the peak at 26° in
2θ. The diffraction peaks of the catalyst (Pt–Ru/C) are
observed to be sharp with a high intensity indicating high
crystallinity (Fig. 2a). On the contrary, very broad peaks
with weak intensity are observed for PAMAM containing
composites (Pt–Ru/PAMAM-CNF), indicating that they are
not fully crystalline in nature (Fig. 2 b) as observed for the
commercial Pt–Ru/C (JM) (Fig. 2a). Compared with Pt–
Ru/C, the peak intensities of Pt–RuPt–PAMAM/CNF are
lower and the full width at half-maximum (FWHM) for the
peaks are bigger. Bigger FWHM indicates a smaller
average size of metal nanoparticles on PAMAM/CNF
composite. No evidence of peaks related to Ru was found
in these catalysts. The absence of diffraction peaks typical
for Ru can be due to a number of reasons such as Ru not
being dissolved in the Pt lattice, that is, forming a PtRu
alloy and/or the Ru being present in the amorphous form, as
further discussed below [29, 30]. The position of the Pt
(111) peak for the larger (>1.2 nm) sized catalysts is shifted
C (002)
Preparation of the working electrode
Result and discussion
The crystal structures of the catalysts are examined by XRD
as shown in Fig. 2. Characteristic reflections of Pt face-
(a) 20% Pt-Ru-PAMAM/CNF
(b) 20% Pt-Ru/C
Pt (111)
Glassy carbon (GC) (Bas Electrode, 0.07 cm ) is polished to a
mirror finish with 0.05 μm alumina suspensions before each
experiment and served as an underlying substrate of the
working electrode. In order to prepare the composite electrode,
the catalysts are dispersed ultrasonically in water at a
concentration of 1 mg ml−1 and 20-μl aliquot is transferred
on to a polished GC substrate. After the evaporation of water,
the resulting thin catalyst film is covered with 5 wt.% Nafion
solution. Then, the electrode is dried at 353 K and used as the
working electrode. A solution of 1 M CH3OH in 0.5 M
H2SO4 is used to study the methanol oxidation activity.
Intensity (a.u)
2
(a)
(b)
10
20
30
40
50
60
70
2θ (degrees)
Fig. 2 XRD spectra of a Pt–Ru/C, b Pt–Ru–PAMAM/CNF
80
4. 1564
to higher 2θ positions than that for pure Pt that has a
maxima at 39.7645° [31].
The scanning electron micrograph images of commercial
CNFs are shown in Fig. 3a,b. The diameter of the
nanofibers is measured using a Leica Qwin Image Analyzer
and is found to be in the range of 260–250 nm and the
length of about 100 μm. Figure 3c shows the image of Pt–
(a)
(b)
J Solid State Electrochem (2009) 13:1561–1566
Ru–PAMAM/CNF. According to the EDX measurements
(Fig. 4), catalysts prepared in this work contained 20.1 wt.%
of total metal with a Pt/Ru atomic ratio of 1:1.0~1.1, which
agrees well with the stoichiometric ratio of 1:1 used in the
starting mixture.
The TEM image of the prepared Pt–Ru–PAMAM/CNF
catalysts, shown in Fig. 5, reveals that well-dispersed,
spherical particles were anchored onto the external walls of
PAMAM/CNF composite support with an average size of
2.6 nm. There is no agglomeration of Pt–Ru nanoparticles
in the composite, and the Pt–Ru nanoparticles were found
to be uniformly dispersed. In comparison, a commercial
Johnson Matthey Pt–Ru catalyst (20 wt.% on Vulcan) had
an average particle size of 3 nm. The uniform dispersion of
metal nanoparticles on PAMAM/CNF composite is clearly
due to the PAMAM dendrimer, which offers large and
uniform distributed nitrogen-active sites for anchoring
metal ions and metal nanoparticles. In this regard,
PAMAM-functionalized CNF composite are far more
effective supports than the conventional-acid-oxidized
CNF. The conventional-acid oxidation functionalization
leads to the structural damage of CNF, which causes a
large extent of loss in electrical conductivity and thus
potentially reduces the electrocatalytic activity of the
catalyst. The three-dimensional structure, smaller particle
size, and high dispersion of nanoparticles may result in
large valuable Pt surface area and good electrocatalytic
properties toward methanol oxidation.
The electrocatalytic activities for methanol oxidation of
Pt–Ru–PAMAM/CNF and commercial Pt–Ru/C electrocatalysts are analyzed by cyclic voltammetry in an
electrolyte of 0.5 M H2SO4 and 1 M CH3OH at 50 mV/s.
Figure 6 shows the cyclic voltammograms (CVs) of the
synthesized Pt–Ru–PAMAM/CNF and commercial Pt–Ru/C
catalysts in an electrolyte solution of 0.5 M H2SO4 and 1 M
CH3OH. There are two irreversible current peak during the
(c)
Fig. 3 SEM images of a, b CNF and c Pt–Ru–PAMAM/CNF
Fig. 4 EDX spectrum of Pt–Ru–PAMAM/CNF (PtRu 20.1 wt. %; Pt/
Ru=1:1.0~1.1)
5. J Solid State Electrochem (2009) 13:1561–1566
Fig. 5 TEM image of 20% Pt–Ru–PAMAM/CNF catalyst
electro-oxidation of methanol that are typically attributed
on the forward scan peak at around 0.8 V to methanol
electro-oxidation and on the backward peak at 0.6 V to the
faradic oxidation reaction on the Pt of the residual
intermediate species. Both CV curves reveal a similar
shape and peak position, which is also in good agreement
with previous reports for methanol CVs over supported Pt
catalysts. The Pt–Ru–PAMAM/CNF composite shows
higher electrocatalytic activity of methanol oxidation
compared to Pt–Ru/C (JM) catalyst. The enhanced catalytic
activity of Pt–Ru/PAMAM–CNF composite catalyst is due
to higher dispersion of Pt–Ru nanoparticles and may be
better oxidation of CO intermediates during methanol
oxidation [32, 33].
The ratio of the forward anodic peak current (If) to the
reverse anodic peak current (Ib) can be used to describe the
catalyst tolerance to accumulation of carbonaceous species
1565
[34–38]. A higher ratio indicates more effective removal of
the poisoning species on the catalyst surface. The If/Ib ratios
of Pt–Ru–PAMAM/CNF and Pt–Ru/C are 1.36 and 0.87,
respectively, showing better catalyst tolerance of PAMAM/
CNF composites. There is no much decrease in electrocatalytic activity of the Pt–Ru–PAMAM/CNF composite
catalysts on subsequent cycles of methanol oxidation
compared to the Pt–Ru/C catalysts. This not only demonstrates the reproducibility of the results but also the stability
of the nanoparticles on the PAMAM/CNF composite
catalysts.
Similarly, Fig. 7 shows the chronoamperometric studies
of the synthesized sample, which reveals the stability of the
Pt–Ru–PAMAM/CNF catalyst toward the methanol electrooxidation. The results are consistent with the view that
PAMAM is not only stabilizing the Pt–Ru nanoparticles but
is also enhancing the methanol oxidation currents under
chronoamperometric conditions. Pt–Ru nanoparticles are
well stabilized by amine-terminated PAMAM dendrimers.
The high electrocatalytic activity of the Pt–Ru–PAMAM/
CNF composite electrodes prepared in this work is most
probably due to the very high dispersion of PtRu particles
and the extensive presence of RuOxHy.
Conclusions
In summary, well-dispersed Pt–Ru nanoparticles have been
synthesized on PAMAM–CNFs composite. The choice of
the PAMAM G4-NH2 dendrimer template and terminal
amine functional groups provides for uniform preparation
of size monodisperse catalysts and facilitates the controlled
dispersion. The enhancements in activity and stability over
Pt–Ru/PAMAM–CNF catalyst have been solely attributed
to high dispersion Pt–Ru nanoparticles on the composite.
0.040
(a) 20% Pt-Ru-PAMAM/CNF
Current (A)
0.035
(b) 20% Pt-Ru/C
0.030
0.025
0.020
0.015
(a)
0.010
(b)
0.005
0.000
0
500
1000
1500
2000
2500
3000
3500
Time (s)
Fig. 6 Cyclic voltammogram of a Pt–Ru–PAMAM/CNF and b Pt–
Ru/C in electrolyte solution of 0.5 M H2SO4 with 1 M CH3OH at a
sweep rate of 50 mV/S at room temperature
Fig. 7 Chronoamperometry of a Pt–Ru–PAMAM/CNF, b Pt–Ru/C
polarized at +0.6 V in 0.5 M H2SO4/1 M CH3OH
6. 1566
These findings suggest that Pt–Ru–PAMAM/CNF should
be considered a good electrocatalyst material for direct
methanol fuel cells. Though more work is needed to
understand the fundamentals of the interaction between
metal nanoparticles and dendrimers, particularly Pt–Ru–
PAMAM/CNF, they show a potential as new electrocatalysts for low temperature fuel cells.
References
1. McNicol BD, Rand DAJ, Williams KR (2001) J Power Sources
83:47 doi:10.1016/S0378-7753(01)00882-5
2. Carrette L, Friedrich KA, Stimming U (2001) Fuel Cells (Weinh) 1:5
doi:10.1002/1615-6854(200105)1:1<5::AID-FUCE5>3.0.CO;2-G
3. Uchida M, Aoyama Y, Tanabe N, Yanagihara N, Eda N, Ohta A
(1995) J Electrochem Soc 142:2572 doi:10.1149/1.2050055
4. Antolini E (2007) Appl Catal B Enviromental 724:324
doi:10.1016/j.apcatb.2007.03.002
5. Matsumoto T, Komatsu T, Arai K, Yamazaki T, Kijima M,
Shimizu H, Takasawa Y, Nakamura J (2004) Chem Commun
7:840 doi:10.1039/b400607k
6. Bessel CA, Laubernds K, Rodriguez NM, Baker RTK (2001) J
Phys Chem B 105:1115 doi:10.1021/jp003280d
7. Steigerwalt ES, Deluga GA, Lukehart CM (2002) J Phys Chem B
106:760 doi:10.1021/jp012707t
8. Li WZ, Liang CH, Zhou WJ, Xin Q (2003) J Phys Chem B
107:6292 doi:10.1021/jp022505c
9. Kim C, Kim YJ, Kim YA, Yanagisawam T, Park KC, Endo M,
Dresselhaus MS (2004) J Appl Phys 96:5903 doi:10.1063/1.1804242
10. Wang C, Waje M, Wang X, Tang JM, Haddon RC, Yan YS (2004)
Nano Lett 4:345 doi:10.1021/nl034952p
11. Maiyalagan T (2008) Appl Catal B Enviromental 89:286
doi:10.1016/j.apcatb.2007.11.033
12. Maiyalagan T, Viswanathan B, Varadaraju UV (2005) Electrochem Commun 7:905 doi:10.1016/j.elecom.2005.07.007
13. Yoshitake T, Shimakawa Y, Kuroshima S, Kimura H, Ichihashi T, Kubo
Y (2002) Physica B 323:124 doi:10.1016/S0921-4526(02)00871-2
14. Hyeon T, Han S, Sung YE, Park KW, Kim YW (2003) Angew
Chem Int Ed 42:4352 doi:10.1002/anie.200250856
15. Yu RQ, Chen LW, Liu QP (1998) Chem Mater 10:718
doi:10.1021/cm970364z
16. Knecht MR, Wright DW (2004) Chem Mater 16:4890
doi:10.1021/cm049058t
J Solid State Electrochem (2009) 13:1561–1566
17. Zhao MQ, Crooks RM (1999) Adv Mater 11:217 doi:10.1002/(SICI)
1521-4095(199903)11:3<217::AID-ADMA217>3.0.CO;2-7
18. Zhao MQ, Crooks RM (1999) Chem Mater 11:3379 doi:10.1021/
cm990435p
19. Ye H, Crooks RM (2005) J Am Chem Soc 127:4930 doi:10.1021/
ja0435900
20. Zhao M, Crooks RM (1999) Adv Mater 11:217 doi:10.1002/(SICI)
1521-4095(199903)11:3<217::AID-ADMA217>3.0.CO;2-7
21. Ye H, Crooks RM (2007) J Am Chem Soc 129:3627
22. Ledesma-Garci J, Escalante Garci IL, Rodri FJ, Chapman TW,
Godinez LA (2008) J Appl Electrochem 38:515 doi:10.1007/
s10800-007-9466-2
23. Vijayaraghavan G, Stevenson KJ (2007) Langmuir 23:5279
doi:10.1021/la0637263
24. Wasmus S, Küver A (1999) J Electroanal Chem 461:14
doi:10.1016/S0022-0728(98)00197-1
25. Gasteiger HA, Markovic N, Ross PN, Cairns EJ (1994) J Phys
Chem 98:617 doi:10.1021/j100053a042
26. Gonzalez-Fuentes MA, Manrıquez J, Gutierrez-Granados S,
Alatorre-Ordaz A, Godınez LA (2005) Chem Commun 8:898
doi:10.1039/b412442a
27. Kim JW, Choi E-A, Park S-M (2003) J Electrochem Soc 150:
E202 doi:10.1149/1.1554727
28. Raghu S, Nirmal RG, Mathiyarasu J, Berchmans S, Phani KLN,
Yegnaraman V (2007) Catal Lett 119:40 doi:10.1007/s10562-0079154-1
29. Wang DL, Zhuang L, Lu JT (2007) J Phys Chem C 111:16416
doi:10.1021/jp073062l
30. Guo JS, Sun GQ, Sun SG, Yan SY, Yang WQ, Qi J, Yan YS, Xin Q
(2007) J Power Sources 168:299 doi:10.1016/j.jpowsour.2007.02.085
31. Bock C, Paquet C, Couillard M, Botton GA, MacDougall B
(2004) J Am Chem Soc 126:8028 doi:10.1021/ja0495819
32. Jarvi TD, Stuve EM (1998) In: Lipkowski J, Ross PN (eds)
Electrocatalysis, frontiers of electrochemistry series, Chapter 3.
Wiley-VCH, New York, pp 75–153
33. Mukerjee S, McBreen J (1998) J Electroanal Chem 448:163
doi:10.1016/S0022-0728(97)00018-1
34. Mu Y, Liang H, Hu J, Jiang L, Wan L (2005) J Phys Chem B
109:22212 doi:10.1021/jp0555448
35. Manoharan R, Goodenough JB (1992) J Mater Chem 2:875
doi:10.1039/jm9920200875
36. Liu Z, Ling XY, Su X, Lee JY (2004) J Phys Chem B 108:8234
doi:10.1021/jp049422b
37. Deivaraj TC, Lee JY (2005) J Power Sources 142:43 doi:10.1016/
j.jpowsour.2004.10.010
38. Maiyalagan T, Nawaz Khan F (2008) J Nanosci Nanotechnol
doi:10.1016/j.catcom.2008.10.011