To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black thr...To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black through a strategy involving modified glycol reduction and chemical etching.The obtained Pt36Co/C catalyst exhibits a much larger electrochemical surface area(ECSA)and an improved ORR electrocatalytic activity compared to commercial Pt/C.Moreover,an electrode prepared with Pt36Co/C was further evaluated under H2-air single cell test conditions,and exhibited a maximum specific power density of 10.27 W mgPt^-1,which is 1.61 times higher than that of a conventional Pt/C electrode and also competitive with most state-of-the-art Pt-based architectures.In addition,the changes in ECSA,power density,and reacting resistance during the accelerated degradation process further demonstrate the enhanced durability of the Pt36Co/C electrode.The superior performance observed in this work can be attributed to the synergy between the ultrasmall size and homogeneous distribution of catalyst nanoparticles,bimetallic ligand and electronic effects,and the dissolution of unstable Co with the rearrangement of surface structure brought about by acid etching.Furthermore,the accessible raw materials and simplified operating procedures involved in the fabrication process would result in great cost-effectiveness for practical applications of PEMFCs.展开更多
Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the v...Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the vigorous support of China's national policy, research institutes and enterprises have carried out extensive and pragmatic work on the basic materials, key components, stacks, auxiliary systems of PEMFCs, as well as the hydrogen station construction in order to realize the wide application of hydrogen energy.PEMFC System and Engineering Research Center of DICP is one of the earliest players in the H2-PEMFCs field.Advances have been achieved in the fields of low-platinum contained catalysts,PEMs, high-efficiency MEAs, low-cost metal bipolar plates, low-temperature and impurity air environment adaptability, stacks and systems.This paper introduces recent progresses of H2-PEMFCs at DICP in key materials, components, stacks, systems and the applications.The engineering status of proton exchange membrane water electrolysis(PEMWE) and the alkaline anion exchange membrane fuel cells(AEMFCs)are also summarized.展开更多
Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells （PEMFCs）. Electrochemical results and single cell tests show that an en...Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells （PEMFCs）. Electrochemical results and single cell tests show that an enhanced activity for the oxygen reduction reaction （ORR） is obtained for the Pt/WO3/C catalyst compared with Pt/C. The higher catalytic activity might be ascribed to the improved Pt dispersion with smaller particle sizes. The Pt/WO3/C catalyst also exhibits a good electrochemical stability under potential cycling. Thus, the Pt/WO3/C catalyst can be used as a potential PEMFC cathode catalyst.展开更多
The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this stu...The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this study, membrane electrode assemblies with different Pt-loadings were prepared, and PEMFCs were assembled using those membrane electrode assemblies with traditional solid plate and water transport plate as cathode flow-field plates, respectively. The performance and electrochemical surface area of cells were characterized to evaluate the membrane electrode assemblies degradation after rapid currentvariation cycles. Scanning electron microscope and transmission electron microscope were used to investigate the decay of catalyst layers and Pt/C catalyst. With the increase of Pt-loading, the performance degradation of membrane electrode assemblies will be mitigated. But higher Pt-loading means thicker catalyst layer, which leads to a longer pathway of mass transfer, and it may result in carbon material corrosion in membrane electrode assemblies. The decay of Pt/C catalyst in cathode is mainly caused by the corrosion of carbon support, and the degradation of anode Pt/C catalyst is a consequence of migration and aggregation of Pt particles. And using water transport plate is beneficial to alleviating the age of cathode Pt/C catalyst.展开更多
Ordered porous cabon with a 2-D hexagonal structure,high specific surface area and large pore volume was synthesized through a twostep heating method using tri-block copolymer as template and phenolic resin as carbon ...Ordered porous cabon with a 2-D hexagonal structure,high specific surface area and large pore volume was synthesized through a twostep heating method using tri-block copolymer as template and phenolic resin as carbon precursor.The results indicated the electrochemical performance of the sulfur/carbon composites prepared with the ordered porous carbon was significantly affected by the pore structure of the carbon.Both the specific capacity and cycling stability of the sulfur/carbon composites were improved using the bimodal micro/meso-porous carbon frameworks with high surface area.Its initial discharge capacity can be as high as 1200 mAh·g-1 at a current density of 167.5 mA·g-1The improved capacity retention was obtained during the cell cycling as well.展开更多
The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the fi...The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers.To gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were conducted.Similar to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process.However,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and reliability.The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.展开更多
In this paper, 1,2,4-triazolium methanesulfonate （C_2H_4N_3^＋-CH_3SO_3^-, [Tri][MS]）, an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reac...In this paper, 1,2,4-triazolium methanesulfonate （C_2H_4N_3^＋-CH_3SO_3^-, [Tri][MS]）, an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reached up to 36.51 mS·cm^-1 at 190 ℃. [Tri][MS] was first applied to modify Nation membrane to fabricate [Tri][MS]/Nafion membrane by impregnation method at 150 ℃. The prepared composite membrane showed high thermal stability with decomposed temperature above 200 ℃ in air atmosphere. In addition, the membrane indicated good ionic conductivity with 3.67 mS·cm^-1 at 140 ℃ and reached up to 13.23 mS·cm^-1 at 180 ℃. The structure of the [Tri][MS] and the composite membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry （CV） method. Besides, the [Tri][MS]/Nafion membrane （thickness of 65 μm） was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion membrane was 3.20 mW·cm^-2 at 140 ℃ and 4.90 mW·cm^-2 at 150 ℃, which was much higher than that of Nation membrane.展开更多
Cibotium barometz(Linn.)J.Sm.,a tree fern in the Dicksoniaceae family,is an economically important industrial exported plant in China and widely used in Traditional Chinese Medicine.C.barometz produces a range of bioa...Cibotium barometz(Linn.)J.Sm.,a tree fern in the Dicksoniaceae family,is an economically important industrial exported plant in China and widely used in Traditional Chinese Medicine.C.barometz produces a range of bioactive triterpenes and their metabolites.However,the biosynthetic pathway of triterpenes in C.barometz remains unknown.To clarify the origin of diverse triterpenes in C.barometz,we conducted de novo transcriptome sequencing and analysis of C.barometz rhizomes and leaves to identify the candidate genes involved in C.barometz triterpene biosynthesis.Three C.barometz triterpene synthases(CbTSs)candidate genes were obtained.All of them were highly expressed in C.barometz rhizomes,consisting of the accumulation pattern of triterpenes in C.barometz.To characterize the function of these CbTSs,we constructed a squalene-and oxidosqualene-overproducing yeast chassis by overexpressing all the enzymes in the MVA pathway under the control of GAL-regulated promoter and disrupted the GAL80 gene in Saccharomyces cerevisiae simultaneously.Heterologous expressing CbTS1,CbTS2,and CbTS3 in engineering yeast strain produced cycloartenol,dammaradiene,and diploptene,respectively.Phylogenetic analysis revealed that CbTS1 belongs to oxidosqualene cyclase,while CbTS2 and CbTS3 belong to squalene cyclase.These results decipher enzymatic mechanisms underlying the origin of diverse triterpene in C.barometz.展开更多
Climate change is a major modern-day challenge that faces the human society. Developing clean energy technology requires near-term approaches and long- term strategy. A solution to meet the daunting challenge is for u...Climate change is a major modern-day challenge that faces the human society. Developing clean energy technology requires near-term approaches and long- term strategy. A solution to meet the daunting challenge is for us to make a switch in energy use to various carbon-free, renewable sources. Due to the intermittency and geographical constraint of renewable energy supply, its broad application requires to develop smart energy storage and conversion technology. Distributed system, microgrid and clean vehicles are among the major society-level solutions that are actively considered. Electrochemical energy, if made in a highly efficient and clean manner, should greatly help in our ability to adapt to this change.展开更多
In this paper, ultrathin Pt nanowires （Pt NWs） and PtNi alloy nanowires （PtNi NWs） supported on carbon were synthesized as electrocatalysts for oxygen reduction reaction （ORR）. Pt and PtNi NWs catalysts composed...In this paper, ultrathin Pt nanowires （Pt NWs） and PtNi alloy nanowires （PtNi NWs） supported on carbon were synthesized as electrocatalysts for oxygen reduction reaction （ORR）. Pt and PtNi NWs catalysts composed of interconnected nanoparticles were prepared by using a soft template method with CTAB as the surface active agent. The physical characterization and electrocatalytic perfor- mance of Pt NWs and PtNi NWs catalysts for ORR were investigated and the results were compared with the commercial Pt/C catalyst. The atomic ratio of Pt and Ni in PtNi alloy was approximately 3 to 1. The results show that after alloying with Ni, the binding energy of Pt shifts to higher values, indicating the change of its electronic structure, and that Pt3Ni NWs catalyst has a significantly higher electrocatalytic activity and good stability for ORR as compared to Pt NWs and even Pt/C catalyst. The enhanced electrocatalytic activity of Pt3Ni NWs catalyst is mainly resulted from the downshifted-band center of Pt caused by the interaction between Pt and Ni in the alloy, which facilitates the desorption of oxygen containing species （Oads or OHads） and the release of active sites.展开更多
Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu na...Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu nanoparticles with the particle size (40 of 3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method. It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction. PtRu/WMC-F7 with D-p > 2d(pt) exhibits the largest electrochemical surface area (ESA) and the highest activity toward methanol electrooxidation. With the decrease in Dp, PtRu/WMC-F30 and PtRu/WMC-F0 have much lower ESA and electrochemical activity, especially for the isopropanol electrooxidation with a larger molecular size. When D-p is more than twice d(pt), the mass transfer of reactants and electrolyte are easier, and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.Th...Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 run.Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area（ECA）,and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72（36 mV） under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti0.7Sn0.3O2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.展开更多
基金supported by the National Major Research Project(2016YFB0101208)the National Natural Science Foundation of China(21576257)+1 种基金the Natural Science Foundation-Liaoning United Fund(U1508202)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB06050303)~~
文摘To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black through a strategy involving modified glycol reduction and chemical etching.The obtained Pt36Co/C catalyst exhibits a much larger electrochemical surface area(ECSA)and an improved ORR electrocatalytic activity compared to commercial Pt/C.Moreover,an electrode prepared with Pt36Co/C was further evaluated under H2-air single cell test conditions,and exhibited a maximum specific power density of 10.27 W mgPt^-1,which is 1.61 times higher than that of a conventional Pt/C electrode and also competitive with most state-of-the-art Pt-based architectures.In addition,the changes in ECSA,power density,and reacting resistance during the accelerated degradation process further demonstrate the enhanced durability of the Pt36Co/C electrode.The superior performance observed in this work can be attributed to the synergy between the ultrasmall size and homogeneous distribution of catalyst nanoparticles,bimetallic ligand and electronic effects,and the dissolution of unstable Co with the rearrangement of surface structure brought about by acid etching.Furthermore,the accessible raw materials and simplified operating procedures involved in the fabrication process would result in great cost-effectiveness for practical applications of PEMFCs.
基金supported by the National Key Research and Development Program of China(2016YFB0101207)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB06050303)the Natural Science Foundation of China(U1664259)
文摘Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the vigorous support of China's national policy, research institutes and enterprises have carried out extensive and pragmatic work on the basic materials, key components, stacks, auxiliary systems of PEMFCs, as well as the hydrogen station construction in order to realize the wide application of hydrogen energy.PEMFC System and Engineering Research Center of DICP is one of the earliest players in the H2-PEMFCs field.Advances have been achieved in the fields of low-platinum contained catalysts,PEMs, high-efficiency MEAs, low-cost metal bipolar plates, low-temperature and impurity air environment adaptability, stacks and systems.This paper introduces recent progresses of H2-PEMFCs at DICP in key materials, components, stacks, systems and the applications.The engineering status of proton exchange membrane water electrolysis(PEMWE) and the alkaline anion exchange membrane fuel cells(AEMFCs)are also summarized.
基金financially supported by the National Natural Science Fundation of China(No.51125007)the National Basic Research Program(No.2012CB215500)
文摘Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells （PEMFCs）. Electrochemical results and single cell tests show that an enhanced activity for the oxygen reduction reaction （ORR） is obtained for the Pt/WO3/C catalyst compared with Pt/C. The higher catalytic activity might be ascribed to the improved Pt dispersion with smaller particle sizes. The Pt/WO3/C catalyst also exhibits a good electrochemical stability under potential cycling. Thus, the Pt/WO3/C catalyst can be used as a potential PEMFC cathode catalyst.
基金financially supported by the National Key Research and Development Program of China (Grant no.2016YFB0101208)NSFC-Liaoning Joint Funding (Grant no. U1508202)the National Natural Science Foundations of China (Grant no. 61433013 and 91434131)
文摘The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this study, membrane electrode assemblies with different Pt-loadings were prepared, and PEMFCs were assembled using those membrane electrode assemblies with traditional solid plate and water transport plate as cathode flow-field plates, respectively. The performance and electrochemical surface area of cells were characterized to evaluate the membrane electrode assemblies degradation after rapid currentvariation cycles. Scanning electron microscope and transmission electron microscope were used to investigate the decay of catalyst layers and Pt/C catalyst. With the increase of Pt-loading, the performance degradation of membrane electrode assemblies will be mitigated. But higher Pt-loading means thicker catalyst layer, which leads to a longer pathway of mass transfer, and it may result in carbon material corrosion in membrane electrode assemblies. The decay of Pt/C catalyst in cathode is mainly caused by the corrosion of carbon support, and the degradation of anode Pt/C catalyst is a consequence of migration and aggregation of Pt particles. And using water transport plate is beneficial to alleviating the age of cathode Pt/C catalyst.
基金supported by the National High Technology Research and Development Program of China(863 Program)the Strategic Priority Research Program of the Chinese Academy of Sciences
文摘Ordered porous cabon with a 2-D hexagonal structure,high specific surface area and large pore volume was synthesized through a twostep heating method using tri-block copolymer as template and phenolic resin as carbon precursor.The results indicated the electrochemical performance of the sulfur/carbon composites prepared with the ordered porous carbon was significantly affected by the pore structure of the carbon.Both the specific capacity and cycling stability of the sulfur/carbon composites were improved using the bimodal micro/meso-porous carbon frameworks with high surface area.Its initial discharge capacity can be as high as 1200 mAh·g-1 at a current density of 167.5 mA·g-1The improved capacity retention was obtained during the cell cycling as well.
基金National Key Point Research and Invention Program of the Thirteenth(Program Nos.2018YFB0105601 and 2017YFB0102801).
文摘The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers.To gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were conducted.Similar to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process.However,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and reliability.The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.
基金financially supported by the National Basic Research Program of China(973 ProgramGrant 2012CB215504)the National Natural Science Foundation of China(21203191 and 21306190)
文摘In this paper, 1,2,4-triazolium methanesulfonate （C_2H_4N_3^＋-CH_3SO_3^-, [Tri][MS]）, an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reached up to 36.51 mS·cm^-1 at 190 ℃. [Tri][MS] was first applied to modify Nation membrane to fabricate [Tri][MS]/Nafion membrane by impregnation method at 150 ℃. The prepared composite membrane showed high thermal stability with decomposed temperature above 200 ℃ in air atmosphere. In addition, the membrane indicated good ionic conductivity with 3.67 mS·cm^-1 at 140 ℃ and reached up to 13.23 mS·cm^-1 at 180 ℃. The structure of the [Tri][MS] and the composite membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry （CV） method. Besides, the [Tri][MS]/Nafion membrane （thickness of 65 μm） was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion membrane was 3.20 mW·cm^-2 at 140 ℃ and 4.90 mW·cm^-2 at 150 ℃, which was much higher than that of Nation membrane.
基金the National Natural Science Foundation of China(No.81874333)the Key Laboratory of Guangdong Drug Administration(2021ZDB03)the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515130005).
文摘Cibotium barometz(Linn.)J.Sm.,a tree fern in the Dicksoniaceae family,is an economically important industrial exported plant in China and widely used in Traditional Chinese Medicine.C.barometz produces a range of bioactive triterpenes and their metabolites.However,the biosynthetic pathway of triterpenes in C.barometz remains unknown.To clarify the origin of diverse triterpenes in C.barometz,we conducted de novo transcriptome sequencing and analysis of C.barometz rhizomes and leaves to identify the candidate genes involved in C.barometz triterpene biosynthesis.Three C.barometz triterpene synthases(CbTSs)candidate genes were obtained.All of them were highly expressed in C.barometz rhizomes,consisting of the accumulation pattern of triterpenes in C.barometz.To characterize the function of these CbTSs,we constructed a squalene-and oxidosqualene-overproducing yeast chassis by overexpressing all the enzymes in the MVA pathway under the control of GAL-regulated promoter and disrupted the GAL80 gene in Saccharomyces cerevisiae simultaneously.Heterologous expressing CbTS1,CbTS2,and CbTS3 in engineering yeast strain produced cycloartenol,dammaradiene,and diploptene,respectively.Phylogenetic analysis revealed that CbTS1 belongs to oxidosqualene cyclase,while CbTS2 and CbTS3 belong to squalene cyclase.These results decipher enzymatic mechanisms underlying the origin of diverse triterpene in C.barometz.
文摘Climate change is a major modern-day challenge that faces the human society. Developing clean energy technology requires near-term approaches and long- term strategy. A solution to meet the daunting challenge is for us to make a switch in energy use to various carbon-free, renewable sources. Due to the intermittency and geographical constraint of renewable energy supply, its broad application requires to develop smart energy storage and conversion technology. Distributed system, microgrid and clean vehicles are among the major society-level solutions that are actively considered. Electrochemical energy, if made in a highly efficient and clean manner, should greatly help in our ability to adapt to this change.
文摘In this paper, ultrathin Pt nanowires （Pt NWs） and PtNi alloy nanowires （PtNi NWs） supported on carbon were synthesized as electrocatalysts for oxygen reduction reaction （ORR）. Pt and PtNi NWs catalysts composed of interconnected nanoparticles were prepared by using a soft template method with CTAB as the surface active agent. The physical characterization and electrocatalytic perfor- mance of Pt NWs and PtNi NWs catalysts for ORR were investigated and the results were compared with the commercial Pt/C catalyst. The atomic ratio of Pt and Ni in PtNi alloy was approximately 3 to 1. The results show that after alloying with Ni, the binding energy of Pt shifts to higher values, indicating the change of its electronic structure, and that Pt3Ni NWs catalyst has a significantly higher electrocatalytic activity and good stability for ORR as compared to Pt NWs and even Pt/C catalyst. The enhanced electrocatalytic activity of Pt3Ni NWs catalyst is mainly resulted from the downshifted-band center of Pt caused by the interaction between Pt and Ni in the alloy, which facilitates the desorption of oxygen containing species （Oads or OHads） and the release of active sites.
基金supported by the National Natural Science Foundation of China (no. 91434106)
文摘Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu nanoparticles with the particle size (40 of 3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method. It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction. PtRu/WMC-F7 with D-p > 2d(pt) exhibits the largest electrochemical surface area (ESA) and the highest activity toward methanol electrooxidation. With the decrease in Dp, PtRu/WMC-F30 and PtRu/WMC-F0 have much lower ESA and electrochemical activity, especially for the isopropanol electrooxidation with a larger molecular size. When D-p is more than twice d(pt), the mass transfer of reactants and electrolyte are easier, and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金supported by the National High Technology Research and Development Program of China(863 Program,Grant No.2013AA110201)the National Basic Research Program of China(973 Program,Grant No.2012CB215500)the National Natural Science Foundations of China(Grant No.21203191)
文摘Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 run.Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area（ECA）,and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72（36 mV） under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti0.7Sn0.3O2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.
文摘在无表面活性剂存在条件下,采用NaBH4还原CuCl_2得到Cu纳米颗粒,以此为助分散剂,进一步还原CuCl_2与K_2PtCl_4得到平均粒径为2.1 nm的PtCu合金纳米颗粒,并被担载到活性炭上.超小的单分散PtCu合金纳米颗粒表现出明显的晶格紧缩、一定程度的Pt表面偏析、较高比例的非氧化态Pt单质和较高的电子结合能,进而表现出较弱的Pt与含氧物种的吸附作用强度.半电池测试得到的0.9 V vs.RHE处氧还原催化(ORR)的面积比活性、质量比活性分别达到Pt/C(JM)的6.6倍和3.8倍,并且加速衰减测试后,ORR电催化活性优势仍很明显,表现出良好的稳定性.在全电池100 mA/cm^2测试条件下,超小的合金催化剂显示出优于Pt/C(JM)的电催化活性及稳定性.本文制备方法也可应用于得到担载型超小单分散PtCo、PtNi等合金纳米颗粒.
