tA highly efficient, recyclable and magnetically separable core-shell structured CuZnO@Fe3O4microspherewrapped with reduced graphene oxide (rGO@CuZnO@Fe3O4) photocatalyst has been developed and usedfor the photoreduction of carbon dioxide with water to produce methanol under visible light irradiation.Owing to the synergistic effect of the components and to the presence of a thin Fe2O3layer on Fe3O4,rGO@CuZnO@Fe3O44 exhibited higher catalytic activity as compared to the other possible combinationssuch as CuZnO@Fe3O42 and GO@CuZnO@Fe3O43 microspheres. The yield of methanol in case of using2 and 3 as photocatalyst was found to be 858 and 1749 mol g−1cat, respectively. However, the yieldwas increased to 2656 mol g−1cat when rGO@CuZnO@Fe3O44 was used as photocatalyst under sim-ilar experimental conditions. This superior photocatalytic activity of 4 was assumed to be due to therestoration of the sp2hybridized aromatic system in rGO, which facilitated the movement of electronsand resulted in better charge separation. The synthesized heterogeneous photocatalyst could readily berecovered by external magnet and successfully reused for six subsequent cycles without significant loss in the product yield.
tA highly efficient, recyclable and magnetically separable core-shell structured CuZnO@Fe3O4microspherewrapped with reduced graphene oxide (rGO@CuZnO@Fe3O4) photocatalyst has been developed and usedfor the photoreduction of carbon dioxide with water to produce methanol under visible light irradiation.Owing to the synergistic effect of the components and to the presence of a thin Fe2O3layer on Fe3O4,rGO@CuZnO@Fe3O44 exhibited higher catalytic activity as compared to the other possible combinationssuch as CuZnO@Fe3O42 and GO@CuZnO@Fe3O43 microspheres. The yield of methanol in case of using2 and 3 as photocatalyst was found to be 858 and 1749 mol g−1cat, respectively. However, the yieldwas increased to 2656 mol g−1cat when rGO@CuZnO@Fe3O44 was used as photocatalyst under sim-ilar experimental conditions. This superior photocatalytic activity of 4 was assumed to be due to therestoration of the sp2hybridized aromatic system in rGO, which facilitated the movement of electronsand resulted in better charge separation. The synthesized heterogeneous photocatalyst could readily berecovered by external magnet and successfully reused for six subsequent cycles without significant loss in the product yield.
CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p, p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at~ 425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of− 225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long …
CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p,p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at ~425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of −225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long-lived charge separated states. Pristine nitrogen doped graphene and its coupled system with plasmonic Ag nanoparticles showed superior photocatalytic performance compared to bare plasmonic Ag catalyst. While standalone Ag NPs were unable to complete the transformation of 4-NBT into DMAB even at a laser power of 10 mW, NGr/Ag nanohybrids completed this transformation at a laser power of 1 mW, pointing to the high photoreduction strength of NGr/Ag. Density functional theory (DFT) based computational modeling was used to examine the electronic structure of graphene doped with graphitic, pyridinic and pyrrolic nitrogen dopant atoms. DFT results indicated an enhanced chemical reactivity of NGr due to stronger localization of charge at the dopant sites and a pronounced difference in the projected density of states (PDOS) for carbon atoms in proximity to, and distant from, the nitrogen dopant sites.
Visible light driven photocatalytic oxidation of thiols to disulfides using i...Pawan Kumar
The present paper describes the synthesis of graphene oxide immobilized iron phthalocyanine (FePc) for the photocatalytic oxidation of thiols to disulfides under alkaline free conditions. Iron phthalocyanine tetrasulfonamide was immobilized on carboxylated graphene oxide supports via covalent attachment.
The loading of FePc on GO nanosheets was confirmed by FTIR, Raman, ICP-AES, UV-Vis and elemental analyses. The synthesized catalyst was found to be highly efficient for the photo-oxidation of thiols to
disulfides in aqueous medium using molecular oxygen as oxidant under visible light irradiation. The identification of photo-oxidation products and their quantitative determination was done using GC-MS. After completion of the reaction, the catalyst was easily recovered by filtration and reused for several runs without loss in activity and no leaching was observed during the reaction.
GRAPHENE SYNTHESIS AND ITS APPLICATIONS TERM PAPER PRESENTATIONAman Gupta
For free download Subscribe to https://www.youtube.com/channel/UCTfiZ8qwZ_8_vTjxeCB037w and Follow https://www.instagram.com/fitrit_2405/ then please contact +91-9045839849 over WhatsApp.
Graphene synthesis process and its current and future applications explained in brief
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide (rGO)-copper oxide nanocomposites were prepared by covalent grafting of CuO nanorods on the rGO skeleton. The chemical and structural features of rGO-CuO nanocomposites were studied by FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO-CuO nanocomposites was explored for reduction of CO2 into the methanol under visible light irradiation. The breadth of CuO nanorods and the oxidation state of Cu in rGO-CuO/Cu2O nanocomposites were systematically varied to investigate their porosity and photocatalytic activities. The pristine CuO nanorods exhibited very low activity because of fast recombination of charge carriers and yielded methanol only 175 µmol g-1, whereas rGO-Cu2O and rGO-CuO exhibited significantly improved photocatalytic activities and yielded five (862 µmol g-1) and seven (1228 µmol g-1) times more methanol, respectively. The superior photocatalytic activities of CuO in rGO-CuO nanocomposites were attributed to the slow recombination of charge carriers and efficient transfer of photo-generated electrons through the rGO skeleton. This study further excludes the use of scavenging donor.
Graphite oxide (GO) formerly called graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally oxidized bulk product is a yellow solid with C:O ratio between 2.1 and 2.9, that retains the layer structure of graphite but with a much larger and irregular spacing.
Structure proposed in 1998 with functional groups. A: Epoxy bridges, B: Hydroxyl groups, C: Pairwise carboxyl groups.
The bulk material spontaneously disperses in basic solutions or can be dispersed by sonication in polar solvents to yield monomolecular sheets, known as graphene oxide by analogy to graphene, the single-layer form of graphite. Graphene oxide sheets have been used to prepare strong paper-like materials, membranes, thin films, and composite materials. Initially, graphene oxide attracted substantial interest as a possible intermediate for the manufacture of graphene. The graphene obtained by reduction of graphene oxide still has many chemical and structural defects which is a problem for some applications but an advantage for some others .Graphite oxide was first prepared by Oxford chemist Benjamin C. Brodie in 1859, by treating graphite with a mixture of potassium chlorate and fuming nitric acid.He reported synthesis of "paper-like foils" with 0.05 mm thickness. In 1957 Hummers and Offeman developed a safer, quicker, and more efficient process called Hummers' method, using a mixture of sulfuric acid H2SO4, sodium nitrate NaNO3, and potassium permanganate KMnO4, which is still widely used, often with some modifications. Largest monolayer GO with highly intact carbon framework and minimal residual impurity concentrations can be synthesized in inert containers using highly pure reactants and solvents.
Graphite oxides demonstrate considerable variation of properties depending on the degree of oxidation and the synthesis method. For example, the temperature point of explosive exfoliation is generally higher for graphite oxide prepared by the Brodie method compared to Hummers graphite oxide, the difference is up to 100 degrees with the same heating rates.Hydration and solvation properties of Brodie and Hummers graphite oxides are also remarkably different.Recently a mixture of H2SO4 and KMnO4 has been used to cut open carbon nanotubes lengthwise, resulting in microscopic flat ribbons of graphene, a few atoms wide, with the edges "capped" by oxygen atoms (=O) or hydroxyl groups (-OH).
Graphite (graphene) oxide has also been prepared by using a "bottom-up" synthesis method (Tang-Lau method) in which the sole source is glucose, the process is safer, simpler, and more environmentally friendly compared to traditionally "top-down" method, in which strong oxidizers are involved. Another important advantage of the Tang-Lau method is the control of thickness, ranging from monolayer to multilayers, by adjusting growth parameters.
Recent development in graphene technology for multidiscilinary properties and...Srajan Gupta
The paper enlightens the future research in the field of material science. it gives a broad view over wide range of its applications and its sustainability. this paper is a combination of various fields in which graphene has proven itself to be the best out of rest. this paper takes you to a journey for each and every part of applications along with is properties followed by its behavior
Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional...Pawan Kumar
We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts
containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign
carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen
source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization
under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich
heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM,
HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was
explored for base-free selective oxidative esterification of alcohols to the corresponding esters under
mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned.
Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with longchain
alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability
of the catalyst facilitated by its ease of separation for long-term performance and recycling studies
showed that the catalyst was robust and remained active even after six recycling experiments.
EPR measurements were performed to deduce the reaction mechanism in the presence of POBN
(α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of
•CH2OH radicals and H• radicals, wherein the solvent plays an active role in a nonconventional manner.
A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR
findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and
S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional...Pawan Kumar
We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were …
Learn why monitoring your Mercedes' Exhaust Back Pressure (EBP) sensor is crucial. Understand its role in engine performance and emission reduction. Discover five warning signs of EBP sensor failure, from loss of power to increased emissions. Take action promptly to avoid costly repairs and maintain your Mercedes' reliability and efficiency.
Implementing ELDs or Electronic Logging Devices is slowly but surely becoming the norm in fleet management. Why? Well, integrating ELDs and associated connected vehicle solutions like fleet tracking devices lets businesses and their in-house fleet managers reap several benefits. Check out the post below to learn more.
CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p, p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at~ 425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of− 225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long …
CVD grown nitrogen doped graphene is an exceptional visible-light driven phot...Pawan Kumar
The photocatalytic potential of large area CVD grown nitrogen doped graphene (NGr) has been explored though the chemical transformation of 4-nitrobenzene thiol into p,p'-dimercaptoazobenzene. Decoration of NGr with Ag nanocubes with rounded edges to form NGr/Ag nanohybrids resulted in a slight increase in the work-function and a decrease in the n-type character of NGr due to ground state transfer of negative charge from NGr to Ag. The Ag nanocubes exhibited a localized surface plasmon resonance (LSPR) at ~425 nm. When the NGr/Ag nanohybrids were illuminated with visible light of wavelength close to the LSPR peak, Kelvin probe force microscopy (KPFM) indicated a dramatic change in surface potential of −225 mV and Raman spectra detected electron accumulation in NGr, which are attributed to a high local field enhancement-mediated hot electron injection into NGr and the formation of long-lived charge separated states. Pristine nitrogen doped graphene and its coupled system with plasmonic Ag nanoparticles showed superior photocatalytic performance compared to bare plasmonic Ag catalyst. While standalone Ag NPs were unable to complete the transformation of 4-NBT into DMAB even at a laser power of 10 mW, NGr/Ag nanohybrids completed this transformation at a laser power of 1 mW, pointing to the high photoreduction strength of NGr/Ag. Density functional theory (DFT) based computational modeling was used to examine the electronic structure of graphene doped with graphitic, pyridinic and pyrrolic nitrogen dopant atoms. DFT results indicated an enhanced chemical reactivity of NGr due to stronger localization of charge at the dopant sites and a pronounced difference in the projected density of states (PDOS) for carbon atoms in proximity to, and distant from, the nitrogen dopant sites.
Visible light driven photocatalytic oxidation of thiols to disulfides using i...Pawan Kumar
The present paper describes the synthesis of graphene oxide immobilized iron phthalocyanine (FePc) for the photocatalytic oxidation of thiols to disulfides under alkaline free conditions. Iron phthalocyanine tetrasulfonamide was immobilized on carboxylated graphene oxide supports via covalent attachment.
The loading of FePc on GO nanosheets was confirmed by FTIR, Raman, ICP-AES, UV-Vis and elemental analyses. The synthesized catalyst was found to be highly efficient for the photo-oxidation of thiols to
disulfides in aqueous medium using molecular oxygen as oxidant under visible light irradiation. The identification of photo-oxidation products and their quantitative determination was done using GC-MS. After completion of the reaction, the catalyst was easily recovered by filtration and reused for several runs without loss in activity and no leaching was observed during the reaction.
GRAPHENE SYNTHESIS AND ITS APPLICATIONS TERM PAPER PRESENTATIONAman Gupta
For free download Subscribe to https://www.youtube.com/channel/UCTfiZ8qwZ_8_vTjxeCB037w and Follow https://www.instagram.com/fitrit_2405/ then please contact +91-9045839849 over WhatsApp.
Graphene synthesis process and its current and future applications explained in brief
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide (rGO)-copper oxide nanocomposites were prepared by covalent grafting of CuO nanorods on the rGO skeleton. The chemical and structural features of rGO-CuO nanocomposites were studied by FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO-CuO nanocomposites was explored for reduction of CO2 into the methanol under visible light irradiation. The breadth of CuO nanorods and the oxidation state of Cu in rGO-CuO/Cu2O nanocomposites were systematically varied to investigate their porosity and photocatalytic activities. The pristine CuO nanorods exhibited very low activity because of fast recombination of charge carriers and yielded methanol only 175 µmol g-1, whereas rGO-Cu2O and rGO-CuO exhibited significantly improved photocatalytic activities and yielded five (862 µmol g-1) and seven (1228 µmol g-1) times more methanol, respectively. The superior photocatalytic activities of CuO in rGO-CuO nanocomposites were attributed to the slow recombination of charge carriers and efficient transfer of photo-generated electrons through the rGO skeleton. This study further excludes the use of scavenging donor.
Graphite oxide (GO) formerly called graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally oxidized bulk product is a yellow solid with C:O ratio between 2.1 and 2.9, that retains the layer structure of graphite but with a much larger and irregular spacing.
Structure proposed in 1998 with functional groups. A: Epoxy bridges, B: Hydroxyl groups, C: Pairwise carboxyl groups.
The bulk material spontaneously disperses in basic solutions or can be dispersed by sonication in polar solvents to yield monomolecular sheets, known as graphene oxide by analogy to graphene, the single-layer form of graphite. Graphene oxide sheets have been used to prepare strong paper-like materials, membranes, thin films, and composite materials. Initially, graphene oxide attracted substantial interest as a possible intermediate for the manufacture of graphene. The graphene obtained by reduction of graphene oxide still has many chemical and structural defects which is a problem for some applications but an advantage for some others .Graphite oxide was first prepared by Oxford chemist Benjamin C. Brodie in 1859, by treating graphite with a mixture of potassium chlorate and fuming nitric acid.He reported synthesis of "paper-like foils" with 0.05 mm thickness. In 1957 Hummers and Offeman developed a safer, quicker, and more efficient process called Hummers' method, using a mixture of sulfuric acid H2SO4, sodium nitrate NaNO3, and potassium permanganate KMnO4, which is still widely used, often with some modifications. Largest monolayer GO with highly intact carbon framework and minimal residual impurity concentrations can be synthesized in inert containers using highly pure reactants and solvents.
Graphite oxides demonstrate considerable variation of properties depending on the degree of oxidation and the synthesis method. For example, the temperature point of explosive exfoliation is generally higher for graphite oxide prepared by the Brodie method compared to Hummers graphite oxide, the difference is up to 100 degrees with the same heating rates.Hydration and solvation properties of Brodie and Hummers graphite oxides are also remarkably different.Recently a mixture of H2SO4 and KMnO4 has been used to cut open carbon nanotubes lengthwise, resulting in microscopic flat ribbons of graphene, a few atoms wide, with the edges "capped" by oxygen atoms (=O) or hydroxyl groups (-OH).
Graphite (graphene) oxide has also been prepared by using a "bottom-up" synthesis method (Tang-Lau method) in which the sole source is glucose, the process is safer, simpler, and more environmentally friendly compared to traditionally "top-down" method, in which strong oxidizers are involved. Another important advantage of the Tang-Lau method is the control of thickness, ranging from monolayer to multilayers, by adjusting growth parameters.
Recent development in graphene technology for multidiscilinary properties and...Srajan Gupta
The paper enlightens the future research in the field of material science. it gives a broad view over wide range of its applications and its sustainability. this paper is a combination of various fields in which graphene has proven itself to be the best out of rest. this paper takes you to a journey for each and every part of applications along with is properties followed by its behavior
Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional...Pawan Kumar
We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts
containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign
carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen
source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization
under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich
heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM,
HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was
explored for base-free selective oxidative esterification of alcohols to the corresponding esters under
mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned.
Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with longchain
alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability
of the catalyst facilitated by its ease of separation for long-term performance and recycling studies
showed that the catalyst was robust and remained active even after six recycling experiments.
EPR measurements were performed to deduce the reaction mechanism in the presence of POBN
(α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of
•CH2OH radicals and H• radicals, wherein the solvent plays an active role in a nonconventional manner.
A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR
findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and
S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional...Pawan Kumar
We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were …
Similar to RGO and GO studies 11 01 2023.docx (20)
Learn why monitoring your Mercedes' Exhaust Back Pressure (EBP) sensor is crucial. Understand its role in engine performance and emission reduction. Discover five warning signs of EBP sensor failure, from loss of power to increased emissions. Take action promptly to avoid costly repairs and maintain your Mercedes' reliability and efficiency.
Implementing ELDs or Electronic Logging Devices is slowly but surely becoming the norm in fleet management. Why? Well, integrating ELDs and associated connected vehicle solutions like fleet tracking devices lets businesses and their in-house fleet managers reap several benefits. Check out the post below to learn more.
How To Fix The Key Not Detected Issue In Mercedes CarsIntegrity Motorcar
Experiencing a "Key Not Detected" problem in your Mercedes? Don’t take it for granted. Go through this presentation to find out the exact nature of the issue you are dealing with. Have your vehicle checked by a certified professional if necessary.
Ever been troubled by the blinking sign and didn’t know what to do?
Here’s a handy guide to dashboard symbols so that you’ll never be confused again!
Save them for later and save the trouble!
The Octavia range embodies the design trend of the Škoda brand: a fusion of
aesthetics, safety and practicality. Whether you see the car as a whole or step
closer and explore its unique features, the Octavia range radiates with the
harmony of functionality and emotion
What Is Recruitment Processing Outsourcing (RPO) Services?Impeccable HR
Impeccable HR provides a wide range of RPO services for your bulk hiring needs within a stipulated period. They meticulously build RPO solutions to improve your recruitment process. RPO services are great for budget-conscious recruiters who want high-quality personnel.
Things to remember while upgrading the brakes of your carjennifermiller8137
Upgrading the brakes of your car? Keep these things in mind before doing so. Additionally, start using an OBD 2 GPS tracker so that you never miss a vehicle maintenance appointment. On top of this, a car GPS tracker will also let you master good driving habits that will let you increase the operational life of your car’s brakes.
What Could Be Behind Your Mercedes Sprinter's Power Loss on Uphill RoadsSprinter Gurus
Unlock the secrets behind your Mercedes Sprinter's uphill power loss with our comprehensive presentation. From fuel filter blockages to turbocharger troubles, we uncover the culprits and empower you to reclaim your vehicle's peak performance. Conquer every ascent with confidence and ensure a thrilling journey every time.
Welcome to ASP Cranes, your trusted partner for crane solutions in Raipur, Chhattisgarh! With years of experience and a commitment to excellence, we offer a comprehensive range of crane services tailored to meet your lifting and material handling needs.
At ASP Cranes, we understand the importance of reliable and efficient crane operations in various industries, from construction and manufacturing to logistics and infrastructure development. That's why we strive to deliver top-notch solutions that enhance productivity, safety, and cost-effectiveness for our clients.
Our services include:
Crane Rental: Whether you need a crawler crane for heavy lifting or a hydraulic crane for versatile operations, we have a diverse fleet of well-maintained cranes available for rent. Our rental options are flexible and can be customized to suit your project requirements.
Crane Sales: Looking to invest in a crane for your business? We offer a wide selection of new and used cranes from leading manufacturers, ensuring you find the perfect equipment to match your needs and budget.
Crane Maintenance and Repair: To ensure optimal performance and safety, regular maintenance and timely repairs are essential for cranes. Our team of skilled technicians provides comprehensive maintenance and repair services to keep your equipment running smoothly and minimize downtime.
Crane Operator Training: Proper training is crucial for safe and efficient crane operation. We offer specialized training programs conducted by certified instructors to equip operators with the skills and knowledge they need to handle cranes effectively.
Custom Solutions: We understand that every project is unique, which is why we offer custom crane solutions tailored to your specific requirements. Whether you need modifications, attachments, or specialized equipment, we can design and implement solutions that meet your needs.
At ASP Cranes, customer satisfaction is our top priority. We are dedicated to delivering reliable, cost-effective, and innovative crane solutions that exceed expectations. Contact us today to learn more about our services and how we can support your project in Raipur, Chhattisgarh, and beyond. Let ASP Cranes be your trusted partner for all your crane needs!
Your VW's camshaft position sensor is crucial for engine performance. Signs of failure include engine misfires, difficulty starting, stalling at low speeds, reduced fuel efficiency, and the check engine light. Prompt inspection and replacement can prevent further damage and keep your VW running smoothly.
What Are The Immediate Steps To Take When The VW Temperature Light Starts Fla...Import Motorworks
Learn how to respond when the red temperature light flashes in your VW with this presentation. From checking coolant levels to seeking professional help, follow these steps promptly to prevent engine damage and ensure safety on the road.
What Could Cause The Headlights On Your Porsche 911 To Stop WorkingLancer Service
Discover why your Porsche 911 headlights might flicker out unexpectedly. From aging bulbs to electrical gremlins and moisture mishaps, we're delving into the reasons behind the blackout. Stay tuned to illuminate the road ahead and ensure your lights shine bright for safer journeys.
1. One of the most important differences between GO and rGO is the electrical
conductivity. GO is an insulating or semi-conducting material whereas rGO has excellent
electrical conductivity. RGO is almost as good as pristine graphene.
The inter layer spacing in Graphite is 0.335 nm. In RGO it is 0.335–0.4 nm (rGO) and in
GO it is 0.77–0.9 nm (GO). Ther interlayer spacing in GO increase with humidity. The rGO
reduced using NaBH4 shows considerably large flake diameter of the smallest thickness
and average number of graphene layers.
2. SEM images of GO layers and rGO layers.
IR of GO and RGO
FTIR
3.
4. The composite is synthesized under uncommonly extreme condition, which provides dual
interactions on polysulfides and Li ion to improve Li-S batteries (IMAGE)
5. The graphene oxide (GO) is spontaneously turned into the reduced graphene oxide (rGO)
by the reactions with N,O-carboxymethyl chitosan under 1 Pa and -50 ℃. The integrated
N,O-carboxymethyl chitosan (CC) not only functions as a binder to connect reduced
graphene oxide (rGO) nanosheets in two-dimension for suppressing the shuttle effect of
lithium polysulfides via physical barrier effect, but also provides abundant active sites by
its heteroatoms with lone pair electrons for repelling polysulfide anions and accelerating
lithium-ion transportation. Since the manufacturing process of the laminar N,O-
carboxymethyl chitosan-reduced graphene oxide (CC-rGO) composite is green and
therefore it is also promising to be applied on large scale for high-performance Li-S
batteries.
6. When electrically insulating GO is reduced, formed reduced graphene oxide resembles
graphene but contains residual oxygen and other heteroatoms as well as structural
defects.
Nanocomposites of rGO have been used in lithium ion batteries. Electrically insulating
metal oxide nanoparticles were adsorbed onto rGO to increase the performance highly
insulating nano materials in batteries. The energy storage capacity and cycle stability was
shown to increase for Fe3O4 on rGO versus pure Fe3O4 or Fe2O3. High surface area rGO has
been prepared using microwaves synthesis. The high surface area rGO formed is useful as
an energy storage material in supercapacitors.
Graphene oxide is comprised of a single layer graphene sheet, covalently bonded to
oxygen functional groups on the basal planes and edges of the sheet. On the basal planes,
there are both hydroxyl and epoxy groups; the edges can include carboxyl, carbonyl,
phenol, lactone, and quinone groups. These oxygenated functional groups bind covalently
with the carbon atoms in GO, creating oxidized regions of sp3- hybridized carbon atoms
that disrupt the non-oxidized regions of the original sp2 honeycomb network. Graphene
sheets alone have limited solubility in water due to the strong π-π bonds between layers.
7. The functional groups present on GO are polar, making it very hydrophilic and water-
soluble, which is important for processing and chemical derivatization. On the other hand,
these oxygen-based functional groups can degrade the electronic, mechanical, and
electrochemical properties of GO by creating significant structural defects, reducing
electrical conductivity, and potentially limiting its direct application in batteries, supercaps
and Fuel cells. However, GO can instead be functionalized by partially reducing it to rGO
with various chemical or thermal treatments, in order to facilitate the transport of carriers.
This chemical modification decreases its resistance by several orders of magnitude and
transforms the material into a graphene-like material.
GO/rGO as Energy Storage Device
GO and rGO have an extremely high surface area; therefore, these materials are
considered for usage as electrode materials in batteries and double-layered capacitors, as
well as fuel cells and solar cells (Zhu). Production of GO can be easily scaled-up compared
with other graphene materials, and therefore it may soon be used for energy-related
purposes. Its ability to store hydrogen may, in the future, prove very useful for the storage
of hydrogen fuel cells. Nanocomposites of GO/rGO can also be used for high-capacity
energy storage in lithium ion batteries. In batteries, electrically insulating Titanium oxide,
Iron phosphate nanoparticles were adsorbed onto rGO to increase the performance of
these materials in batteries