Direct ethanol fuel cell is a promising low temperature fuel cell,but its development is hindered by sluggish kinetics of anode catalysts for ethanol oxidation.Here a high efficient platinum/tin oxide/Graphene nanocom...Direct ethanol fuel cell is a promising low temperature fuel cell,but its development is hindered by sluggish kinetics of anode catalysts for ethanol oxidation.Here a high efficient platinum/tin oxide/Graphene nanocomposite is synthesized through a facile and environmentally benign method.The structure and morphology are carefully characterized by X-ray diffraction and Transmission electron microscopy,showing a clear platinum/tin oxide heterostructure uniformly dispersed on graphene support.This catalyst demonstrates the highest activity among the reported catalysts and much higher durability towards ethanol oxidation compared to conventional platinum nanocatalysts.The ultrahigh activity originates from promoted removal of poisoning carbon monoxide immediate species on platinum due to a strong electronic donating effect from both tin oxide and graphene,which is fully supported by carbon monoxide stripping and X-ray photoelectron spectroscopy analysis.Our platinum/tin oxide/Graphene appears to be a promising candidate for ethanol oxidation electrocatalysts.展开更多
Catalysts of carbon monoxide oxidation were synthesized by deposition of platinum on titanium nitride (TiN). Two substrates with an average particle size of 18 and 36 nm were obtained by hydrogen reduction of titanium...Catalysts of carbon monoxide oxidation were synthesized by deposition of platinum on titanium nitride (TiN). Two substrates with an average particle size of 18 and 36 nm were obtained by hydrogen reduction of titanium tetrachloride in a stream of microwave plasma of nitrogen. The surface of the catalysts was studied by X-ray photoelectron spectroscopy (XPS). The data obtained by us in the present work indicate the presence of oxynitride as a transition layer between nitride and oxide. It was found that the CO oxidation rate on the 9 - 15 wt.% Pt loaded TiN catalysts is 120 times higher than that on the platinum black with a specific surface of 30 m<sup>2</sup>/g. Increase in the reaction rate of CO oxidation on Pt/TiN catalysts as compared to platinum black can be associated with both an increase in the concentration of CO molecules adsorbed and a decrease in the activation energy of the reaction. Catalysts are promising for use in catalytic air purification systems.展开更多
Three different regeneration processes including hydrogen or nitrogen purging and coke-burning treatment were used to restore the Pt-Sn/γ-AlOcatalysts, through which propane dehydrogenation reaction was performed in ...Three different regeneration processes including hydrogen or nitrogen purging and coke-burning treatment were used to restore the Pt-Sn/γ-AlOcatalysts, through which propane dehydrogenation reaction was performed in a consecutive reaction-regeneration mode. It was found that the catalyst using hydrogen regeneration showed the best stability compared with those regenerated by nitrogen purging and coke-burning treatment, suggesting that hydrogen regeneration is an effective approach for maintaining the performance of Pt-Sn/γ-AlOcatalysts in propane dehydrogenation reaction. The effect of different regeneration atmospheres on the metal active center and the coke deposition was investigated by XRD,TEM, N-physisorption, TPO, TG and Raman technologies, and the results revealed that hydrogen or nitrogen regeneration resulted in little impact on the size and structure of metal active center, retaining the effective Pt Sn phase over the catalyst. Moreover, hydrogen regeneration not only removed the low dense components of the coke, but also altered the property of the residual coke through hydrogenation, leading to a higher mobility of coke, and thus a higher accessibility of the metal active centers. Whereas nitrogen regeneration only removed the low dense components of the coke. Although coke-burning regeneration caused a thorough coke removal, the catalyst subjected to repeated redox exhibited poor stability due to metal agglomeration, phase segregation and the resulting large PtSn particle and core-shell structure with a Sn-rich surface.展开更多
A nanoporous Pt particles-modified Ti （nanoPt/Ti） electrode was prepared through a simple hydrothennal method using aqueous H2PtC16 as a precursor and formaldehyde as a reduction agent. The nanoPt/Ti electrode was t...A nanoporous Pt particles-modified Ti （nanoPt/Ti） electrode was prepared through a simple hydrothennal method using aqueous H2PtC16 as a precursor and formaldehyde as a reduction agent. The nanoPt/Ti electrode was then modified with limited amounts of tin particles generated by cyclic potential scans in the range of -0.20 to 0.50 V in a 0.01 mol,L 1 SnCI2 solution, to synthesize a Sn-modified nanoporous Pt catalyst （SrdnanoPt/Ti）. Electroactivity of the nanoPt/Ti and Sn/nanoPt/Ti electrodes towards formaldehyde oxidation in a 0.5 moloL-I H2804 solution was evaluated by cyclic voltammetry and chronoamperometry. Electrooxidation of formaldehyde on the nanoPt/Ti electrode takes place at a potential of 0.45 V and then presents high anodic current densities due to the large real surface area of the nanoPt/Ti electrode. The formaldehyde oxidation rate is dramatically increased on the Sn/nanoPt/Ti electrode at the most negative potentials, where anodic formaldehyde oxidation is completely suppressed on the nanoPt/Ti electrode. Chronoamperogramms （CA） of the Sn/nanoPt/Ti electrode display stable and large quasisteady state current densities at more negative potential steps. Amperometric data obtained at a potential step of 100 mV show a linear dependence of the current density for formaldehyde oxidation upon formaldehyde concentration in the range of 0.003 to 0.1 mol.L-l with a sensitivity of 59.29 mA^cm-2 （mol,L-l）-1. A detection limit of 0.506 mmol.L-l formaldehyde was found. The superior electroactivity of the Sn/nanoPt/Ti electrode for formaldehyde oxidation can be illustrated by a socalled bifunctional mechanism which is involved in the oxidation of poisoning adsorbed CO species via the surface reaction with OH adsorbed on neighboring Sn sites.展开更多
To enhance the cycling stability of Pt-based catalysts,the anti-corrosion property of support and the attachment of Pt with support should both get improved.For this purpose,a novel method is presented for in situ pre...To enhance the cycling stability of Pt-based catalysts,the anti-corrosion property of support and the attachment of Pt with support should both get improved.For this purpose,a novel method is presented for in situ preparing Pt/SnO_2.The structure of Pt/ SnO_2 is characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）,confirming the homogeneous deposition of Pt on SnO_2.The high resolution TEM（HRTEM） shows the large interfaces between Pt and SnO_2.The TEM photos recorded after accelerated durability tests with Pt/SnO_2 show that the agglomeration and size increment of Pt particles is not severe, indicating the good stability of Pt/SnO_2.The electrochemical active surface area（EAS） of Pt/SnO_2 keeps increasing during the 1000 cycles of cyclic voltammetric（CV） sweeping in H_2SO_4,while the EAS decayed by 35%when mixing Pt/SnO_2 with carbon nanotubes（CNTs）,indicating the superior anti-corrosion property of SnO_2 in contrast to CNTs.展开更多
基金Project supported by the Key Special Projects of the Ministry of Science and Technology(China:2021YFE0104300 and Uzbekistan:MUK-2021-45)Project(202302AH360001)supported by the Science Research Project of Yunnan Province,ChinaProject(2021P4FZG09A)supported by the Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization,China。
基金grateful to the financial support from the Key Research and Development Project of Tianjin(18ZXJMTG00180)the National Nature Science Foundation of China(21433003)~~
文摘Direct ethanol fuel cell is a promising low temperature fuel cell,but its development is hindered by sluggish kinetics of anode catalysts for ethanol oxidation.Here a high efficient platinum/tin oxide/Graphene nanocomposite is synthesized through a facile and environmentally benign method.The structure and morphology are carefully characterized by X-ray diffraction and Transmission electron microscopy,showing a clear platinum/tin oxide heterostructure uniformly dispersed on graphene support.This catalyst demonstrates the highest activity among the reported catalysts and much higher durability towards ethanol oxidation compared to conventional platinum nanocatalysts.The ultrahigh activity originates from promoted removal of poisoning carbon monoxide immediate species on platinum due to a strong electronic donating effect from both tin oxide and graphene,which is fully supported by carbon monoxide stripping and X-ray photoelectron spectroscopy analysis.Our platinum/tin oxide/Graphene appears to be a promising candidate for ethanol oxidation electrocatalysts.
文摘Catalysts of carbon monoxide oxidation were synthesized by deposition of platinum on titanium nitride (TiN). Two substrates with an average particle size of 18 and 36 nm were obtained by hydrogen reduction of titanium tetrachloride in a stream of microwave plasma of nitrogen. The surface of the catalysts was studied by X-ray photoelectron spectroscopy (XPS). The data obtained by us in the present work indicate the presence of oxynitride as a transition layer between nitride and oxide. It was found that the CO oxidation rate on the 9 - 15 wt.% Pt loaded TiN catalysts is 120 times higher than that on the platinum black with a specific surface of 30 m<sup>2</sup>/g. Increase in the reaction rate of CO oxidation on Pt/TiN catalysts as compared to platinum black can be associated with both an increase in the concentration of CO molecules adsorbed and a decrease in the activation energy of the reaction. Catalysts are promising for use in catalytic air purification systems.
基金supported by the National Natural Science Foundation of China(nos.21103182,21273049)the Natural Science Foundation of Guangdong Province(no.S2013050014127)Education Department Funding of Guangdong Province(nos.CGZHZD1104,2013CXZDA016).
文摘Three different regeneration processes including hydrogen or nitrogen purging and coke-burning treatment were used to restore the Pt-Sn/γ-AlOcatalysts, through which propane dehydrogenation reaction was performed in a consecutive reaction-regeneration mode. It was found that the catalyst using hydrogen regeneration showed the best stability compared with those regenerated by nitrogen purging and coke-burning treatment, suggesting that hydrogen regeneration is an effective approach for maintaining the performance of Pt-Sn/γ-AlOcatalysts in propane dehydrogenation reaction. The effect of different regeneration atmospheres on the metal active center and the coke deposition was investigated by XRD,TEM, N-physisorption, TPO, TG and Raman technologies, and the results revealed that hydrogen or nitrogen regeneration resulted in little impact on the size and structure of metal active center, retaining the effective Pt Sn phase over the catalyst. Moreover, hydrogen regeneration not only removed the low dense components of the coke, but also altered the property of the residual coke through hydrogenation, leading to a higher mobility of coke, and thus a higher accessibility of the metal active centers. Whereas nitrogen regeneration only removed the low dense components of the coke. Although coke-burning regeneration caused a thorough coke removal, the catalyst subjected to repeated redox exhibited poor stability due to metal agglomeration, phase segregation and the resulting large PtSn particle and core-shell structure with a Sn-rich surface.
基金This work was supported by the National Natural Science Foundation of China （No. 20876038）, Hunan Provincial Natural Science Foundation of China and Xiangtan Natural Science United Foundation of China （No. 10JJ9003） and the Planned Science and Technology Project of Hunan Province, China （No. 2009GK3084）.
文摘A nanoporous Pt particles-modified Ti （nanoPt/Ti） electrode was prepared through a simple hydrothennal method using aqueous H2PtC16 as a precursor and formaldehyde as a reduction agent. The nanoPt/Ti electrode was then modified with limited amounts of tin particles generated by cyclic potential scans in the range of -0.20 to 0.50 V in a 0.01 mol,L 1 SnCI2 solution, to synthesize a Sn-modified nanoporous Pt catalyst （SrdnanoPt/Ti）. Electroactivity of the nanoPt/Ti and Sn/nanoPt/Ti electrodes towards formaldehyde oxidation in a 0.5 moloL-I H2804 solution was evaluated by cyclic voltammetry and chronoamperometry. Electrooxidation of formaldehyde on the nanoPt/Ti electrode takes place at a potential of 0.45 V and then presents high anodic current densities due to the large real surface area of the nanoPt/Ti electrode. The formaldehyde oxidation rate is dramatically increased on the Sn/nanoPt/Ti electrode at the most negative potentials, where anodic formaldehyde oxidation is completely suppressed on the nanoPt/Ti electrode. Chronoamperogramms （CA） of the Sn/nanoPt/Ti electrode display stable and large quasisteady state current densities at more negative potential steps. Amperometric data obtained at a potential step of 100 mV show a linear dependence of the current density for formaldehyde oxidation upon formaldehyde concentration in the range of 0.003 to 0.1 mol.L-l with a sensitivity of 59.29 mA^cm-2 （mol,L-l）-1. A detection limit of 0.506 mmol.L-l formaldehyde was found. The superior electroactivity of the Sn/nanoPt/Ti electrode for formaldehyde oxidation can be illustrated by a socalled bifunctional mechanism which is involved in the oxidation of poisoning adsorbed CO species via the surface reaction with OH adsorbed on neighboring Sn sites.
文摘To enhance the cycling stability of Pt-based catalysts,the anti-corrosion property of support and the attachment of Pt with support should both get improved.For this purpose,a novel method is presented for in situ preparing Pt/SnO_2.The structure of Pt/ SnO_2 is characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）,confirming the homogeneous deposition of Pt on SnO_2.The high resolution TEM（HRTEM） shows the large interfaces between Pt and SnO_2.The TEM photos recorded after accelerated durability tests with Pt/SnO_2 show that the agglomeration and size increment of Pt particles is not severe, indicating the good stability of Pt/SnO_2.The electrochemical active surface area（EAS） of Pt/SnO_2 keeps increasing during the 1000 cycles of cyclic voltammetric（CV） sweeping in H_2SO_4,while the EAS decayed by 35%when mixing Pt/SnO_2 with carbon nanotubes（CNTs）,indicating the superior anti-corrosion property of SnO_2 in contrast to CNTs.
