1) The document describes a novel process for depositing well-dispersed platinum nanoparticles on carbon nanotubes as a catalyst for direct methanol fuel cells.
2) The process uses triphenylphosphine molecules to modify platinum nanoparticles, allowing them to be deposited from solution onto carbon nanotubes in a controllable manner.
3) Characterization with transmission electron microscopy shows the platinum nanoparticles are highly dispersed and uniform on the carbon nanotube surfaces after deposition, with control over the platinum loading level, and that the nanoparticles aggregate slightly after heat treatment but remain well dispersed.
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.
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 doped graphene nanosheet supported platinum nanoparticles as high pe...Science Padayatchi
Functional carbon nanomaterials are significantly important for the development of high performance
sensitive and selective electrochemical biosensors. In this study, graphene supported platinum
nanoparticles (GN–PtNPs) and nitrogen doped graphene supported platinum nanoparticles (N-GN–
PtNPs) were synthesized by a simple chemical reduction method and explored as high performance
nanocatalyst supports, as well as doped nanocatalyst supports, toward electrochemical oxidation of
homocysteine (HCY) for the first the time. Our studies demonstrate that N-doped graphene supported
PtNPs show higher electrocatalytic activity for HCY with an experimental detection limit of 200 pM.
Moreover, N-doped graphene supported Pt was demonstrated to have excellent selectivity in the
electrochemical oxidation of HCY i.e., the detection of HCY is successful in the presence of a 20-fold
excess of ascorbic acid (AA). The practical application of N-doped graphene supported PtNP materials is
effectively shown for the determination of HCY in both human blood serum and urine samples, by
differential pulse voltammetry under optimized conditions. Our findings conclude that N-doped
graphene supported PtNPs can be developed as a high performance and versatile nano-electrocatalyst
for electrochemical biosensor applications.
Effect of ordering of PtCu3 electrocatalyst structure on the stability for ox...Nejc Hodnik
Presentation at the 10th European Symposium on Electrochemical Engineering, Sardinia, Italy
September 28, 2014 to October 02, 2014
Authors:
Nejc Hodnik1,2, C. Jeyabharathi1,3, K. Phani3, A. Rečnik4, M. Bele2, S. Hočevar2, M. Gaberšček2 and K. Mayrhofer1
1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Department of Interface Chemistry and Surface Engineering
Electrocatalysis Group
2National Institute of Chemistry, Ljubljana, Slovenia
3CSIR-Central Electrochemical Research Institute, Tamil Nadu, India
4Jožef Stefan Institute, Ljubljana, Slovenia
This document presents an electrochemical and computational study of oxygen reduction reaction (ORR) on nonprecious transition metal/nitrogen doped carbon nanofiber catalysts. Electrochemical measurements showed that pyrolyzed Fe/N/C catalyst promotes a four-electron ORR pathway, while O2 reduction on Co/N/C occurs mainly via a two-electron pathway. Density functional theory calculations predicted that ORR could occur through a four-electron associative pathway on an FeN4 active site, but may terminate after two electrons on a CoN4 site due to high activation energy for O-O bond splitting. The results suggest that FeN4 and CoN4 clusters may be the main active sites for
The document summarizes a study that used a palladium catalyst to synthesize benzofuran through a Sonogashira coupling reaction between 5-iodovanillin and 3-methyl-3-butyne-2-ol. The reaction was carried out using various amounts of palladium acetate, triphenylphosphine, and solvent. NMR spectroscopy showed the product formed, though it was impure likely due to side reactions promoted by the copper co-catalyst. While the reaction showed good atom economy, the yields were relatively low at 7.45% maximum. Further optimization is needed to improve purity and yields.
This document summarizes research on using amine-rich nitrogen-doped carbon nanodots (NCNDs) as a co-reactant platform for electrochemiluminescence (ECL). The NCNDs were found to enhance the ECL signal of ruthenium tris(bipyridine) through their primary and tertiary amino groups acting as co-reactants in the ECL process. Methylated NCNDs, with tertiary amino groups, showed an even higher ECL signal than unmodified NCNDs. Additionally, a covalently linked hybrid of NCNDs and ruthenium tris(bipyridine) exhibited self-enhanced ECL, with the NCND
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.
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 doped graphene nanosheet supported platinum nanoparticles as high pe...Science Padayatchi
Functional carbon nanomaterials are significantly important for the development of high performance
sensitive and selective electrochemical biosensors. In this study, graphene supported platinum
nanoparticles (GN–PtNPs) and nitrogen doped graphene supported platinum nanoparticles (N-GN–
PtNPs) were synthesized by a simple chemical reduction method and explored as high performance
nanocatalyst supports, as well as doped nanocatalyst supports, toward electrochemical oxidation of
homocysteine (HCY) for the first the time. Our studies demonstrate that N-doped graphene supported
PtNPs show higher electrocatalytic activity for HCY with an experimental detection limit of 200 pM.
Moreover, N-doped graphene supported Pt was demonstrated to have excellent selectivity in the
electrochemical oxidation of HCY i.e., the detection of HCY is successful in the presence of a 20-fold
excess of ascorbic acid (AA). The practical application of N-doped graphene supported PtNP materials is
effectively shown for the determination of HCY in both human blood serum and urine samples, by
differential pulse voltammetry under optimized conditions. Our findings conclude that N-doped
graphene supported PtNPs can be developed as a high performance and versatile nano-electrocatalyst
for electrochemical biosensor applications.
Effect of ordering of PtCu3 electrocatalyst structure on the stability for ox...Nejc Hodnik
Presentation at the 10th European Symposium on Electrochemical Engineering, Sardinia, Italy
September 28, 2014 to October 02, 2014
Authors:
Nejc Hodnik1,2, C. Jeyabharathi1,3, K. Phani3, A. Rečnik4, M. Bele2, S. Hočevar2, M. Gaberšček2 and K. Mayrhofer1
1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Department of Interface Chemistry and Surface Engineering
Electrocatalysis Group
2National Institute of Chemistry, Ljubljana, Slovenia
3CSIR-Central Electrochemical Research Institute, Tamil Nadu, India
4Jožef Stefan Institute, Ljubljana, Slovenia
This document presents an electrochemical and computational study of oxygen reduction reaction (ORR) on nonprecious transition metal/nitrogen doped carbon nanofiber catalysts. Electrochemical measurements showed that pyrolyzed Fe/N/C catalyst promotes a four-electron ORR pathway, while O2 reduction on Co/N/C occurs mainly via a two-electron pathway. Density functional theory calculations predicted that ORR could occur through a four-electron associative pathway on an FeN4 active site, but may terminate after two electrons on a CoN4 site due to high activation energy for O-O bond splitting. The results suggest that FeN4 and CoN4 clusters may be the main active sites for
The document summarizes a study that used a palladium catalyst to synthesize benzofuran through a Sonogashira coupling reaction between 5-iodovanillin and 3-methyl-3-butyne-2-ol. The reaction was carried out using various amounts of palladium acetate, triphenylphosphine, and solvent. NMR spectroscopy showed the product formed, though it was impure likely due to side reactions promoted by the copper co-catalyst. While the reaction showed good atom economy, the yields were relatively low at 7.45% maximum. Further optimization is needed to improve purity and yields.
This document summarizes research on using amine-rich nitrogen-doped carbon nanodots (NCNDs) as a co-reactant platform for electrochemiluminescence (ECL). The NCNDs were found to enhance the ECL signal of ruthenium tris(bipyridine) through their primary and tertiary amino groups acting as co-reactants in the ECL process. Methylated NCNDs, with tertiary amino groups, showed an even higher ECL signal than unmodified NCNDs. Additionally, a covalently linked hybrid of NCNDs and ruthenium tris(bipyridine) exhibited self-enhanced ECL, with the NCND
Fullerene Functionalized Thiophene Derivative as an Acceptor Material for Org...CrimsonPublishersRDMS
Fullerene Functionalized Thiophene Derivative as an Acceptor Material for Organic Photovoltaics by Ranjith Kottokkaran* in Research & Development in Material Science
This document summarizes a study that synthesized titanium dioxide-graphene oxide (TiO2-GO) and titanium dioxide-thermally reduced graphene oxide (TiO2-TGO) composites with varying concentrations of GO/TGO. The composites were characterized using various techniques and their photocatalytic activity for degrading phenol in an aqueous solution was evaluated. The TiO2-0.25% TGO composite exhibited the highest photocatalytic activity, attributed to optimal phenol adsorption and reduced electron-hole pair recombination rates. Photocatalytic testing under nitrogen confirmed the role of graphene in transporting and storing electrons, suppressing recombination.
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.
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.
Organic inorganic hybrid cobalt phthalocyanine/polyaniline as efficient catal...Pawan Kumar
Organic inorganic hybrid catalyst synthesized by doping of cobalt phthalocyanine (CoPc) on polyaniline
support (CoPc/PANI) exhibited higher activity for the oxidation of various alcohols to the corresponding
carbonyl compounds in high to excellent yield using molecular oxygen as oxidant and isobutyraldehyde
as a sacrificial agent. Notably, the synthesized catalyst was found to be truly heterogeneous in nature and
could be easily recovered, recycled for several recycling runs without loss of catalytic activity
Electrochemical sensor for voltammetric determination ofCleophas Rwemera
The document discusses an electrochemical sensor for determining catechol using a screen printed graphite electrode. Cyclic voltammetry was used to study the electrochemical behavior of catechol, which showed reversible one-electron oxidation and reduction peaks. Square wave voltammetry allowed for direct determination of catechol concentration, showing a linear range from 1x10-6 to 1x10-4 M. Interference from ascorbic acid was examined. The method was applied to determine catechol concentration in water samples.
Replacement fuels like biomass and coal dust for thermal power stations presents challenges due to their high moisture and low combustion temperatures. Microwave plasmatrons provide an alternative that can address these issues.
Microwave plasmatrons allow for high temperature plasma ignition without electrodes, providing homogeneous and controllable plasma streams over 12,000°C. This enables more complete and efficient combustion of replacement fuels like biomass and processed coal dust.
Plasma processing of waste materials provides an environmentally-friendly recycling method. It allows for complete molecular decomposition of toxic and non-toxic solid and liquid organic wastes into harmless slag and combustible gases that can be used as fuels.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Maiyalagan,Electro oxidation of methanol on ti o2 nanotube supported platinum...kutty79
TiO2 nanotubes have been synthesized using anodic alumina membrane as template. Highly dispersed
platinum nanoparticles have been supported on the TiO2 nanotube. The supported system
has been characterized by electron microscopy and electrochemical analysis. SEM image shows
that the nanotubes are well aligned and the TEM image shows that the Pt particles are uniformly
distributed over the TiO2 nanotube support. A homogeneous structure in the composite nanomaterials
is indicated by XRD analysis. The electrocatalytic activity ofthe platinum catalyst supported on
TiO2 nanotubes for methanol oxidation is found to be better than that of the standard commercial
E-TEK catalyst.
This presentation by Russell Shapiro provides an overview of an accounting firm agreement, including the process, provisions, governance, retirement, payment period/payment limitations, life insurance, payment protections, compensation, withdrawal/dismissal, restrictive covenants/purchasing clients, firm capital, income partners and amendments.
The University of Texas Hispanic Journalists organization aims to support Hispanic student journalists and those interested in Hispanic issues and bilingual media. The group strives to uphold journalism studies and practices by Hispanics, further career opportunities for Hispanic students, be a voice for the Hispanic community on campus, and encourage student participation in media. The 2012-2013 officers are listed, and the group hosts speakers, tours facilities, provides workshops/mentorships, publishes members' work, volunteers, fundraises, and holds social events.
Este documento describe una actividad de aprendizaje colaborativo realizada por estudiantes mediante el uso de foros y una plataforma virtual. Los estudiantes trabajaron en grupos para elaborar un informe sobre un tema asignado, siguiendo pautas proporcionadas por las profesoras. El proceso les permitió desarrollar su autonomía y responsabilidad mientras intercambiaban ideas con compañeros y profesoras. Tanto docentes como alumnos obtuvieron beneficios de este enfoque de aprendizaje colaborativo medi
This job posting is seeking a major account manager sales representative to be based in the Geneva area. The role involves managing key client accounts and driving sales. Applicants should have experience in sales and account management.
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.
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.
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.
Fullerene Functionalized Thiophene Derivative as an Acceptor Material for Org...CrimsonPublishersRDMS
Fullerene Functionalized Thiophene Derivative as an Acceptor Material for Organic Photovoltaics by Ranjith Kottokkaran* in Research & Development in Material Science
This document summarizes a study that synthesized titanium dioxide-graphene oxide (TiO2-GO) and titanium dioxide-thermally reduced graphene oxide (TiO2-TGO) composites with varying concentrations of GO/TGO. The composites were characterized using various techniques and their photocatalytic activity for degrading phenol in an aqueous solution was evaluated. The TiO2-0.25% TGO composite exhibited the highest photocatalytic activity, attributed to optimal phenol adsorption and reduced electron-hole pair recombination rates. Photocatalytic testing under nitrogen confirmed the role of graphene in transporting and storing electrons, suppressing recombination.
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.
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.
Organic inorganic hybrid cobalt phthalocyanine/polyaniline as efficient catal...Pawan Kumar
Organic inorganic hybrid catalyst synthesized by doping of cobalt phthalocyanine (CoPc) on polyaniline
support (CoPc/PANI) exhibited higher activity for the oxidation of various alcohols to the corresponding
carbonyl compounds in high to excellent yield using molecular oxygen as oxidant and isobutyraldehyde
as a sacrificial agent. Notably, the synthesized catalyst was found to be truly heterogeneous in nature and
could be easily recovered, recycled for several recycling runs without loss of catalytic activity
Electrochemical sensor for voltammetric determination ofCleophas Rwemera
The document discusses an electrochemical sensor for determining catechol using a screen printed graphite electrode. Cyclic voltammetry was used to study the electrochemical behavior of catechol, which showed reversible one-electron oxidation and reduction peaks. Square wave voltammetry allowed for direct determination of catechol concentration, showing a linear range from 1x10-6 to 1x10-4 M. Interference from ascorbic acid was examined. The method was applied to determine catechol concentration in water samples.
Replacement fuels like biomass and coal dust for thermal power stations presents challenges due to their high moisture and low combustion temperatures. Microwave plasmatrons provide an alternative that can address these issues.
Microwave plasmatrons allow for high temperature plasma ignition without electrodes, providing homogeneous and controllable plasma streams over 12,000°C. This enables more complete and efficient combustion of replacement fuels like biomass and processed coal dust.
Plasma processing of waste materials provides an environmentally-friendly recycling method. It allows for complete molecular decomposition of toxic and non-toxic solid and liquid organic wastes into harmless slag and combustible gases that can be used as fuels.
IOSR Journal of Applied Chemistry (IOSR-JAC) is an open access international journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Maiyalagan,Electro oxidation of methanol on ti o2 nanotube supported platinum...kutty79
TiO2 nanotubes have been synthesized using anodic alumina membrane as template. Highly dispersed
platinum nanoparticles have been supported on the TiO2 nanotube. The supported system
has been characterized by electron microscopy and electrochemical analysis. SEM image shows
that the nanotubes are well aligned and the TEM image shows that the Pt particles are uniformly
distributed over the TiO2 nanotube support. A homogeneous structure in the composite nanomaterials
is indicated by XRD analysis. The electrocatalytic activity ofthe platinum catalyst supported on
TiO2 nanotubes for methanol oxidation is found to be better than that of the standard commercial
E-TEK catalyst.
This presentation by Russell Shapiro provides an overview of an accounting firm agreement, including the process, provisions, governance, retirement, payment period/payment limitations, life insurance, payment protections, compensation, withdrawal/dismissal, restrictive covenants/purchasing clients, firm capital, income partners and amendments.
The University of Texas Hispanic Journalists organization aims to support Hispanic student journalists and those interested in Hispanic issues and bilingual media. The group strives to uphold journalism studies and practices by Hispanics, further career opportunities for Hispanic students, be a voice for the Hispanic community on campus, and encourage student participation in media. The 2012-2013 officers are listed, and the group hosts speakers, tours facilities, provides workshops/mentorships, publishes members' work, volunteers, fundraises, and holds social events.
Este documento describe una actividad de aprendizaje colaborativo realizada por estudiantes mediante el uso de foros y una plataforma virtual. Los estudiantes trabajaron en grupos para elaborar un informe sobre un tema asignado, siguiendo pautas proporcionadas por las profesoras. El proceso les permitió desarrollar su autonomía y responsabilidad mientras intercambiaban ideas con compañeros y profesoras. Tanto docentes como alumnos obtuvieron beneficios de este enfoque de aprendizaje colaborativo medi
This job posting is seeking a major account manager sales representative to be based in the Geneva area. The role involves managing key client accounts and driving sales. Applicants should have experience in sales and account management.
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.
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.
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.
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...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.
Oxidized multi walled carbon nanotubes for improving the electrocatalytic act...Iranian Chemical Society
In the present paper, the use of a novel carbon paste electrode modified by 7,8-dihydroxy-3,3,6-trimethyl-3,4-dihydrodibenzo[b,d]furan-1(2H)-one (DTD) and oxidized multi-walled carbon nanotubes (OCNTs) is described for determination of levodopa (LD), acetaminophen (AC) and tryptophan (Trp) by a simple and rapid method. At first, the electrochemical behavior of DTD is studied, then, the mediated oxidation of LD at the modified electrode is investigated. At the optimum pH of 7.4, the oxidation of LD occurs at a potential about 330 mV less positive than that of an unmodified carbon paste electrode. Based on differential pulse voltammetry (DPV), the oxidation current of LD exhibits a linear range between 1.0 and 2000.0 μM of LD with a detection limit (3σ) of 0.36 μM. DPV was also used for simultaneous determination of LD, AC and Trp at the modified electrode. Finally, the proposed electrochemical sensor was used for determinations of these substances in human serum sample.
This document describes a study on the use of PtCo and PtNi nanoparticles supported on graphitic mesoporous carbon (GMC) as electrocatalysts for the electro-oxidation of methanol. The electrocatalysts were prepared using a sequential impregnation reduction method and characterized using various techniques. Their performance for methanol oxidation was evaluated using cyclic voltammetry. The results showed that PtCo/GMC had the highest mass activity and CO tolerance, followed by PtNi/GMC, due to the high metal nanoparticle dispersion and GMC support, which facilitated CO oxidation through a bifunctional mechanism.
Effects of heat treatment on the catalytic activity and methanol tolerance of...sunidevi
This document summarizes a study on the effects of heat treatment on the catalytic activity and methanol tolerance of carbon-supported platinum alloys. Carbon-supported platinum (Pt/C) and platinum alloy (Pt-Co/C, Pt-Cu/C, Pt-Fe/C, Pt-Ni/C) catalysts were subjected to heat treatments at different temperatures. X-ray diffraction, transmission electron microscopy, and electrochemical measurements were used to characterize the catalysts and evaluate their oxygen reduction reaction activity and methanol tolerance. The results showed that heat treatment improved catalytic activity by increasing particle size but the optimal temperature depended on the catalyst. Pt-Cu/C treated at 350°C showed the highest activity and
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.
The document summarizes a study that demonstrated the ability to tune the size of large-diameter, few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50-150 nm by varying the transition metal (TM) used during synthesis. Fe produced the largest tubes, followed by Co and Ni, while Mn resulted in a clot-like morphology. Electrocatalytic activity for the oxygen reduction reaction (ORR) followed the trend Fe > Co > Ni > Mn. Fe-derived N-CNTs exhibited the highest surface area and nitrogen incorporation, contributing to their high ORR activity. This work provides a new route for developing advanced nonprecious metal catalysts by controlling carbon nanot
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...madlovescience
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 samples. The results suggest these catalysts could be promising anode catalysts for direct methanol fuel cells.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
2. Preparation of Well-Dispersed Pt Nanoparticles on CNTs J. Phys. Chem. B, Vol. 109, No. 47, 2005 22213
the protection of N2. The color of the solution began to change
at around 130 °C, implying that Pt precursors were being
reduced and Pt nanoparticles were synthesized. The obtained
Pt colloidal solution is dark brown and homogeneous.
Modification of Pt Nanoparticles. The obtained Pt colloidal
solution (10 mL) was added to 40 mL of ethanol. Then the
mixed solution was added into a toluene solution of PPh3 (50
mL, 3.81 mM) with stirring. A homogeneous, dark brown
solution was obtained. After 15 min, 50 mL of distilled water
was added to the solution. A liquid in two phases was obtained.
The upper dark-brown solution was PPh3-modified Pt/toluene
solution and the bottom colorless solution was the mixed
solution of water and ethanol. The PPh3-modified Pt/toluene
solution was washed with distilled water three times to remove
the ethylene glycol and transfer the Pt nanoparticles from glycol
solution to toluene, which is essential for the deposition of Pt
nanoparticles on CNT walls.
Deposition of Pt Nanoparticles on CNTs. MWCNTs were
used ultrasonically as received in toluene solution for 4 h to
break big CNT aggregates and disperse CNTs. Then PPh3-
modified Pt/toluene solution was added to the CNT/toluene
solution and the mixture was ultrasonicated for 5 days until all
Pt nanoparticles were deposited on CNTs. The toluene solution
became colorless, suggesting that the PPh3-modified Pt nano-particles
were completely deposited on the surface of CNTs.
The Pt/CNT composite was separated from the solution by
centrifugation and washed by toluene three times.
Characterization. The size of the Pt nanoparticles and
morphology of the Pt/CNT composite were observed by TEM
and HRTEM. TEMs were performed on a JEOL2010 equipped
with an energy-dispersive X-ray analyzer (Phoenix) (200 KV).
HRTEM was carried out on a Philips F30 with an acceleration
voltage of 300 kV. For TEM observation, the samples were
dispersed in ethanol by ultrasonic treatment and dropped on
copper grids with carbon films followed by solvent evaporation
in air at room temperature. X-ray powder diffractions (XRD)
were carried out on a Rigaku D/max-2500, using filtered Cu
KR radiation.
Electroactivities of the catalyst were measured by cyclic
voltammetry with use of a three-electrode test cell at room
temperature after the Pt/CNT composite was calcined at 400
°C for 1 h to remove PPh3. A thin film electrode technique was
used to make the measurements. A glassy carbon disk (3 mm
in diameter) held in a Teflon cylinder was used as the working
electrode, on which a thin layer of Nafion-impregnated catalyst
was cast. The Pt loading of both catalysts on electrode was 1
mg/cm2. A Pt wire served as the counter electrode and a
saturated calomel electrode (SCE) was used as the reference
electrode. The electrolyte for electrochemical measurements was
a solution of 2 M methanol in 1 M H2SO4. The solution was
deaerated with ultrahigh-purity N2 before scanning.
Results and Discussion
In view of the inertness of CNT walls, we prepared Pt
colloidal solution in toluene, which is an excellent solvent to
wet CNTs. As illustrated in Figure 1, the organic molecule PPh3
acts as a cross linker for Pt nanoparticles and CNTs. At the
end of the molecule, the free electron pair of P interacts with
the space orbital of Pt to form a coordination compound. And
at the other end of the molecule, the phenyl rings correlate with
the backbone of CNTs. There are three functions of PPh3. At
first, it causes Pt nanoparticles transfer from glycol solution to
toluene solution. Second, it prevents Pt nanoparticles from
aggregating with each other either in toluene solution or on the
Figure 1. Schematic illustrations of the synthesis procedures of Pt/
CNT composite.
Figure 2. TEM images of Pt/CNT composite with different Pt
content: 40.6 (a) (inset: enlarged image of panel a), 24.0 (b), 19.1
(c), and 3.1 wt % (d).
CNTs surface. At last, it links Pt nanoparticles with CNTs and
leads to the uniform dispersion of Pt nanoparticles on CNT
surfaces.
Pt/CNT composites with different Pt content having distinct
application potential were produced by simply manipulating the
ratio of Pt nanoparticles vs CNTs in solution. The as-prepared
Pt/CNT composite nanomaterials were investigated by TEM.
Figure 2a-d shows representative TEM images of as-prepared
Pt/CNT composite with varying content of Pt, from (a) 40.6,
(b) 24.0, (c) 19.1, to (d) 3.1 wt %, respectively. Figure 2a is a
typical TEM image showing the CNTs covered with a continu-ous
Pt nanoparticle adlayer, which extends the overall length
of CNTs. Owing to no pretreatment, the CNTs are flexible and
as long as several tens of micrometers. The insert in Figure 2a
is a high-magnification TEM image of the Pt/CNT composite
nanomaterials. It can be seen that there exists a well-dispersed
Pt nanoparticle adlayer on the wall of a CNT. The PPh3
molecules effectively isolated adjacent Pt nanoparticles. There-fore,
Pt nanoparticles are distributed on tube walls quite
uniformly and do not aggregate with each other to form larger
clusters. The average distance between Pt nanoparticles is less
than 1 nm, which is consistent with the stabilizer PPh3
molecules.
As the content decreases, Pt nanoparticles randomly deposit
on the wall of CNTs and no continuous layer can be found on
the CNT surface as shown in Figure 2, panels b to d. However,
no free Pt nanoparticles can be resolved in these four TEM
images. It is evident that Pt nanoparticles strongly adsorb on
3. 22214 J. Phys. Chem. B, Vol. 109, No. 47, 2005 Mu et al.
Figure 3. (a) TEM image of Pt/CNT composite (24.0 wt %) after thermal treatment at 400 °C for 1 h. (b) EDS from the Pt/CNT composite shown
in panel a. (c) HRTEM image of the Pt/CNT composite shown in panel a.
Figure 4. Size distribution of Pt nanoparticles on CNTs (a) before and (b) after thermal treatment.
the CNT surface. By adjusting the relative ratio of CNTs and
Pt nanoparticles in toluene solution, different coverage of Pt
nanoparticles on the CNT surface can be accomplished, which
is crucial to their industrial applications as catalysts. The above
results have clearly demonstrated the effectiveness of a simple
route for the assembly of Pt nanoparticles on CNTs and that Pt
nanoparticles are loaded on the outside walls of CNTs, not on
the inside walls.
The Pt/CNT composite was investigated by annealing treat-ment
because it is necessary to remove PPh3 molecules
surrounding Pt nanoparticles before the Pt/CNT composite can
be used as a catalyst. Figure 3a is the TEM image of Pt/CNT
composite after thermal treatment at 400 °C for 1 h in ambient
environment. The sample is the same as that shown in Figure
2b. The PPh3 protection layer on Pt nanoparticles should have
been effectively removed because PPh3 decomposes at about
216 °C according to thermogravimetric analysis (not shown
here). With the removal of PPh3, Pt nanoparticles are fused and
aggregate into larger particles. By comparing the size of Pt
nanoparticles in Figures 2b and 3a, it is evident that Pt
nanoparticles in Figure 3a are larger due to the aggregation of
neighboring Pt nanoparticles after heat treatment. The average
size of the Pt nanoparticles on CNTs before thermal treatment
shown in Figure 2b is measured to be 1.9 ( 0.5 nm, close to
that of Pt nanoparticles in toluene solution. Figure 4a is a
statistical result from more than 200 Pt nanoparticles showing
the distribution of the particle size. After thermal treatment, the
mean particle size shown in Figure 3a is measured to be 2.7 (
1.0 nm and most Pt nanoparticles are smaller than 4 nm. Figure
4b is a statistical result from more than 200 Pt nanoparticles
after heat treatment. From the results in Figure 4a,b, it is clear
that the size distribution of Pt nanoparticles is quite narrow
compared to previous reports.13,31 After thermal treatment, Pt
nanoparticles are still well dispersed, which is critical to their
future application as catalysts. One of the advantages of thermal
treatment is to increase the stability of the composite because
the working temperature of DMFCs is much lower than the
thermal treatment temperature. Figure 3b demonstrates the
energy-dispersive X-ray spectroscopy (EDS) of the Pt/CNT
composite shown in Figure 3a. The existence of elemental Pt
can be clearly seen. Figure 3c is a high-resolution transmission
electron micrograph (HRTEM) of the composite shown in
Figure 3a, displaying a layer-by-layer morphology of the tube
wall of the MWCNT and the crystalline facets of Pt nanopar-ticles,
which demonstrate the highly crystalline character of
metallic Pt particles.
The crystalline nature of the Pt nanoparticles was further
confirmed by recording the X-ray power diffraction (XRD)
4. Preparation of Well-Dispersed Pt Nanoparticles on CNTs J. Phys. Chem. B, Vol. 109, No. 47, 2005 22215
spectrum (Figure 5) of Pt/CNT composite after thermal treatment
shown in Figure 3a. The peak at 2õ ) 26.5° corresponds to the
(002) planes of graphitized CNTs. And the peaks at 2õ ) 39.7°,
46.2°, 67.4°, and 81.2° can be assigned to the (111), (200), (220),
and (311) crystalline planes of fcc Pt, respectively, which
indicates that the Pt nanoparticles are composed of pure
crystalline Pt.
The electrochemical performance of the Pt/CNT composite
(24 wt %, shown in Figure 3a) was tested for methanol
oxidation, which is at the heart of DMFC application in the
anodic half-cell reaction. For comparison, the commercial Pt
catalyst (E-TEK, 20 wt %) was also employed. In Figure 6, the
cyclic voltammograms for methanol oxidation at Pt/CNT
composite prepared by our method (solid line) and the com-mercial
catalyst (dash line) are compared. The voltammetric
features are in good agreement with literature,6-8,18 in which
the typical methanol oxidation current peak on Pt catalyst is at
about 0.74 V vs SCE in the forward scan. Figure 6 clearly shows
that the oxidation current observed with Pt/CNT composite is
considerably higher than that of the E-TEK catalyst. This
significant improvement in the catalytic performance can be
attributed to the high level of dispersion of Pt nanoparticles on
CNTs. In the reverse scan, an oxidation peak is observed around
0.53 V, which is primarily associated with the removal of the
residual carbon species formed in the forward scan.4,13,32,33 The
residual carbon species are oxidized according to the following
reaction:
Therefore, the ratio of the forward oxidation current peak (If)
to the reverse current peak (Ib), If/Ib, is an index of the catalyst
tolerance to the poisoning species, PtdCdO. A higher ratio
indicates more effective removal of the poisoning species on
the catalyst surface. The If/Ib ratio of Pt/CNT composite is 0.88,
higher than that of the E-TEK catalyst (0.74), showing better
catalyst tolerance of the Pt/CNT composite.
Conclusions
In summary, a novel method has been successfully developed
to load Pt nanoparticles on CNTs without pretreating the CNTs.
It is unique in the system that the PPh3 offers strong adhesion
of Pt on CNT surface and sufficient protection for Pt nanopar-ticles
from being aggregated. Pt/CNT composite with different
Pt content was conveniently controlled by manipulating the
relative concentration of CNTs vs Pt nanoparticles. Pt nano-particles
highly dispersed on CNTs kept their initial small sizes
in solution. Even though thermal treatment led to some extent
of aggregation of Pt nanoprticles, the sizes of most Pt nano-particles
are still smaller than 4 nm. The produced Pt/CNT
composite shows higher electrocatalytic activities and catalyst
tolerance that can be applied in DMFCs in comparison with
the E-TEK catalyst. The present technique represents a highly
feasible approach to produce Pt/CNT composite, which should
have great potential in DMFC applications.
Acknowledgment. Financial support from National Natural
Science Foundation of China (Nos. 20520140277, 20121301,
and 20575070), National Key Project on Basic Research (Grant
No. G2000077501), and Chinese Academy of Sciences is
gratefully acknowledged.
References and Notes
(1) Olah, G. A. Angew. Chem., Int. Ed. 2005, 44, 2.
(2) Winter, M.; Brodd, R. J. Chem. ReV. 2004, 104, 4245.
(3) Mcnicol, B. D.; Rand, D. A. J.; Williams, K. R. J. Power Sources
1999, 83, 15.
(4) Lamy, C.; Le´ger, J. M.; Srinivasan, S. Mod. Aspects Electrochem.
2001, 34, 73.
(5) Matsumoto, T.; Komatsu, T.; Arai, K.; Yamazaki, T.; Kijima, M.;
Shimizu, H.; Takasawa, Y.; Nakamura, J. Chem. Commun. 2004, 840.
(6) Yu, J. S.; Kanf, S.; Yoon, S. B.; Chai, G. J. Am. Chem. Soc. 2002,
124, 9382.
(7) Chen, W. X.; Lee, J. Y.; Liu, Z. L. Chem. Commun. 2002, 2588
(8) Liang, H. P.; Zhang, H. M.; Hu, J. S.; Guo, Y. G.; Wan, L. J.; Bai,
C. L. Angew. Chem., Int. Ed. 2004, 43, 1540
(9) Anderson, M. L.; Stroud, R. M.; Rolison, D. R. Nano Lett. 2002,
2, 235.
(10) Vinodgopal, K.; Haria, M.; Meisel, D.; Kamat, P. Nano Lett. 2004,
4, 415.
(11) Schmidt, T. J.; Paulus, U. A.; Gasteiger, H. A.; Behm, R. J. J.
Electroanal. Chem. 2001, 508, 41.
(12) Bock, C.; Paquet, C.; Couillard, M.; Botton, G. A.; MacDougall,
B. R. J. Am. Chem. Soc. 2004, 126, 8028.
(13) Liu, Z.; Ling, X. Y.; Su, X.; Lee, J. Y. J. Phys. Chem. B 2004,
108, 8234.
(14) Ebbesen, T. W.; Lezec, H. J.; Hiura, H.; Bennett, J. W.; Ghaemi,
H. F.; Thio, T. Nature 1996, 382, 54.
(15) Baughman, R. H.; Zakhidov, A. A.; Heer, W. A. Science 2002,
297, 787.
(16) Lee, K. M.; Li, L. C.; Dai, L. M. J. Am. Chem. Soc. 2005, 127,
4122.
(17) Rajesh, B.; Thampi, K. R.; Bonard, J. M.; Xanthopoulos, N.;
Mathieu, H. J.; Viswanathan, B. J. Phys. Chem. B 2003, 107, 2701.
(18) Guo, D. J.; Li, H. L. J. Electroanal. Chem. 2004, 573, 197.
(19) Tang, H.; Chen, J. H.; Huang, Z. P.; Wang, D. Z.; Rn, Z. F.; Nie,
L. H.; Kuang, Y. F.; Yao, S. Z. Carbon 2004, 42, 191.
(20) Ang, L. M.; Andy Hor, T. S.; Xu, G. Q.; Tung, C. H.; Zhao, S.;
Wang, J. L. S. Chem. Mater. 1999, 11, 2115.
(21) Yu, R. Q.; Chen, L. W.; Liu, Q. P.; Lin, J. Y.; Tan, K. L.; Ng, S.
C.; Chan, H. S. O.; Xu, G. Q.; Andy Hor, T. S. Chem. Mater. 1998, 10,
718.
Figure 5. XRD pattern of Pt/CNT composite shown in Figure 4a.
3
Figure 6. HCyclic voltammograms of methanol oxidation on Pt/CNT
composite (solid line) and commercial E-TEK Pt/C catalyst (dash line)
in 2 M COH/1 M H2SO4 electrolyte at 20 mV S-1 at room
temperature.
PtOHad + PtdCdO f CO2 + 2Pt + H+ + e-
5. 22216 J. Phys. Chem. B, Vol. 109, No. 47, 2005 Mu et al.
(22) Rajalakshmi, N.; Ryu, H.; Shaijumon, M. M.; Ramaprabhu, S. J.
Power Sources 2005, 140, 250.
(23) Li, W. Z.; Liang, C. H.; Zhou, W. J.; Qiu, J. S.; Zhou, Z. H.; Sun,
G. Q.; Xin, Q. J. Phys. Chem. B 2003, 107, 6292.
(24) Kong, J.; Chapline, M.; Dai, H. AdV. Mater. 2001, 13, 1384.
(25) Bezryadin, A.; Lau, C. N.; Tinkham, M. Nature 2000, 404, 971.
(26) Choi, H. C.; Shim, M.; Bangsaruntip, S.; Dai, H. J. Am. Chem.
Soc. 2002, 124, 9058.
(27) Girishkumar, G.; Vinodgopal, K.; Kamat, P. V. J. Phys. Chem. B
2004, 108, 19960.
(28) Nelson, T.; Vinodgopal, K.; Kumar, G. G.; Kamat, P. Electrochem.
Soc. Proc. 2004, 12, 152.
(29) Quinn, B. M.; Dekker, C.; Lemay, S. G. J. Am. Chem. Soc. 2005,
127, 6146.
(30) Wang, Y.; Ren, J.; Deng, K.; Gui, L.; Tang, Y. Chem. Mater. 2000,
12, 1622.
(31) Xing, Y. J. Phys. Chem. B 2004, 108, 19255.
(32) Yajima, T.; Uchida, H.; Watanabe, M. J. Phys. Chem. B 2004, 108,
2654.
(33) Zhu, Y. M.; Uchida, H.; Yajima, T.; Watanabe, M. Langmuir 2001,
17, 146.