Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts...Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts for both cathode and anode face several problems which hinder the commercialization of DMFCs.In this review, we mainly focus on anode catalysts of DMFCs. The process and mechanism of methanolelectrooxidation on Pt and Pt-based catalysts in acidic medium have been introduced. The influences ofsize effect and morphology on electrocatalytic activity are discussed though whether there is a size effectin MOP, catalyst is under debate. Besides, the non Pt catalysts are also listed to emphasize though Pt isstill deemed as the indispensable element in anode catalyst of DMFCs in acidic medium. Different cata-lyst systems are compared to illustrate the level of research at present. ome debates need to be verifiedwith experimental evidences.展开更多
A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of ...A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.展开更多
Carbon modified TiO_2 nanobelts(TiO_2-C) were synthesized using a hydrothermal growth method,as a support material for palladium(Pd) nanoparticles(Pd/TiO_2-C) to improve the electrocatalytic performance for methanol e...Carbon modified TiO_2 nanobelts(TiO_2-C) were synthesized using a hydrothermal growth method,as a support material for palladium(Pd) nanoparticles(Pd/TiO_2-C) to improve the electrocatalytic performance for methanol electrooxidation by comparison to Pd nanoparticles on bare TiO_2 nanobelts(Pd/TiO_2)and activated carbon(Pd/AC). Cyclic voltammetry characterization was conducted with respect to saturated calomel electrode(SCE) in an alkaline methanol solution, and the results indicate that the specific activity of Pd/TiO_2-C is 2.2 times that of Pd/AC and 1.5 times that of Pd/TiO_2. Chronoamperometry results revealed that the TiO_2-C support was comparable in stability to activated carbon, but possesses an enhanced current density for methanol oxidation at a potential of -0.2 V vs. SCE. The current study demonstrates the potential of Pd nanoparticle loaded on hierarchical TiO_2-C nanobelts for electrocatalytic applications such as fuel cells and batteries.展开更多
Carbon supported Pt（Pt/C） electrocatalysts were prepared with glucose as protection agent and NaBH 4 as reductant.The Pt nanoparticles deposited on carbon support presented reduced size and well dispersity attribute...Carbon supported Pt（Pt/C） electrocatalysts were prepared with glucose as protection agent and NaBH 4 as reductant.The Pt nanoparticles deposited on carbon support presented reduced size and well dispersity attributed to the protection effect of glucose.Glucose absorbed on the particle surface was readily removed by water washing without leading to agglomeration of the Pt nanoparticles.The as-prepared Pt/C electrocatalysts showed improved mass activity for methanol electrooxidation compared to the catalyst prepared without glucose protection.The improved performance is attributed to the larger electrochemical active surface area thus increased active sites on the Pt/C elctrocatalysts prepared under the protection of glucose.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
Direct methanol fuel cells are promising energy-supplying devices for future portable electronics,but the anodic methanol oxidation has been crying out for high-efficiency catalysts.Ruthenium oxide(RuO_(2))exhibits th...Direct methanol fuel cells are promising energy-supplying devices for future portable electronics,but the anodic methanol oxidation has been crying out for high-efficiency catalysts.Ruthenium oxide(RuO_(2))exhibits the capacity to improve the catalytic performance of Pt-based materials,while the underlying mechanism is still not clear.Herein,we constructed carbonencapsulated RuO_(2)clusters supported Pt nanoparticles with enhanced catalytic activity and durability towards the methanol oxidation reaction(MOR),and the in-depth mechanism was studied by in-situ infrared absorption spectrum and first-principles computation.The carbon-encapsulated RuO_(2)clusters alleviated the dissolution of metallic Ru in acidic media and regulated the electronic structure of Pt nanoparticles via the electronic metal-support interaction.In-situ attenuated total reflection-surfaceenhanced infrared absorption spectroscopy(ATR-SEIRAS)tracked the intermediates and confirmed the facilitated dissociation of interfacial water on the Pt-RuO_(2)/C at a low potential of 0.56 V,generating active OH species to promote the oxidative removal of CO intermediates and CO_(2)generation.Theoretical calculations further confirmed the weakened CO adsorption energy on Pt-RuO_(2)as well as the decreased reaction energy barrier of the rate-determining CO oxidation step.As a result,the Pt-RuO_(2)/C showed a MOR peak current density of 68.7 mA cm^(-2),which was 1.7 and 2.9 times that of commercial PtRu/C and Pt/C catalysts.Besides,the current density of Pt-RuO_(2)/C reached 10.4 mA cm^(-2)at 0.66 V,about 3.3 and 5.0 times that of commercial PtRu/C and Pt/C catalysts,indicating good catalytic activity at low potentials.The current work contributes some practical and theoretical basis to the development of a novel Pt-Ru electrocatalyst system for energy conversion techniques.展开更多
Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effec...Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction （MOR） on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.展开更多
Platinum based alloys are hereinto the mostly used methanol oxidation catalysts.However,there are limited ways to improve the methanol oxidation reaction(MOR)performance of catalysts in terms of both activity and stab...Platinum based alloys are hereinto the mostly used methanol oxidation catalysts.However,there are limited ways to improve the methanol oxidation reaction(MOR)performance of catalysts in terms of both activity and stability.Herein we developed a simple heat-treatment method to synthesize PtCu_(3)/C intermetallic compound catalyst with lattice compression.The as-prepared PtCu_(3)/C-1000 exhibited high specific activity of 3.23 mA·cm^(-1) and mass activity of 1,200 mA·mgPt^(-1),which is much higher than the PtCu_(3)/C-untreated and commercial Pt/C catalysts,respectively.The XAS and DFT results shows the high activity of the catalyst towards MOR comes from the tightening of the Pt-M bond,which leads to the decrease of Fermi energy level and the make it difficulty in adsorbing carbon intermediates,thus releasing more active sites to promote the improvement of MOR performance.Moreover,the PtCu_(3)/C-1000 shows better stability which is due to the surface-rich Pt prevents Cu from dissolution.展开更多
Methanol oxidation on smooth Pt electrode modified with different coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current effici...Methanol oxidation on smooth Pt electrode modified with different coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO 2 was calculated from faraday current and ion current of m/z =44. The results show that Ru modified Pt electrode with the coverage of ca . 0 3 has the highest catalytic activity for methanol electrooxidation, i.e. faraday current and the current efficiency of CO 2 at the low potentials reach to the maximum. In addition, Ru loses its co catalytic properties at the high potentials.展开更多
Fe_2O_3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction（MOR） in an alkaline electrolyte.The catalysts were characterized by...Fe_2O_3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction（MOR） in an alkaline electrolyte.The catalysts were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,cyclic voltammetry and chronoamperometry.The results show that the presence of Fe_2O_3 in the electrocatalysts can promote the kinetic processes of MOR on Pt,and this promoting effect is related to the morphology of the Fe_2O_3 promoter.The catalyst with Fe_2O_3 nanorods as the promoter（Pt-Fe_2O_3/C-R） exhibits much higher catalytic activity and stability than that with Fe_2O_3 nanoplates as the promoter（Pt-Fe_2O_3/C-P）.The mass activity and specific activity of Pt in a Pt-Fe_2O_3/C-R catalyst are 5.32 A/mgpt and 162.7 A/m^2_（Pt）,respectively,which are approximately 1.67 and 2.04 times those of the Pt-Fe_2O_3/C-P catalyst,and 4.19 and 6.16 times those of a commercial PtRu/C catalyst,respectively.Synergistic effects between Fe_2O_3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement.These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.展开更多
In the current study, perovskite type LaFNPs （LaFeO3 nanoparticles） were prepared by a rapid microwave-assisted co-precipitation method and their presence was confirmed by XRD, EDX and SEM techniques. LaFNPs and LaF...In the current study, perovskite type LaFNPs （LaFeO3 nanoparticles） were prepared by a rapid microwave-assisted co-precipitation method and their presence was confirmed by XRD, EDX and SEM techniques. LaFNPs and LaFNPs-CNTs （LaFeO3NPs-carbon nanotubes） nanocomposites were successfully prepared. GC （glassy carbon） electrode was modified with LaFNPs and LaFNPs-CNTs for methanol electrooxidation. The electrocatalytic activity of LaFNPs and LaFNPs-CNTs nanocatalysts toward methanol electrooxidation was examined through cyclic voltammetry and chronoamperometry methods. The effect of some experimental factors such as methanol, LaFNPs amounts, electrolyte concentrations and scan rate was studied. The catalytic activity of LaFNPs-CNTs and LaFNPs nanocatalysts was compared with each other. According to the electrochemical investigations, LaFNPs nanocatalyst had a considerable activity for methanol electrooxidation in comparison to LaFNPs nanocatalyst.展开更多
A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation （MEO） has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crysta...A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation （MEO） has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles （PdNPs） with a narrow particle size distribution （3-5 nm） are uni- formly deposited onto the surface of Co304 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst （448 mA/mg Pd）. The dependency of log/against logv reveals that MEO on Pd-CO304 electrode is under a diffusion control. Electrochemical impedance spectroscopy （EIS） measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-CO304 is observed at -0.05 V, which coincides with the potential of MEO peak.展开更多
Carbon-supported platinum catalysts were prepared by NaBH4 reduction of metal precursors and the CeO2 nanoparticles were prepared by citric acid sol-gel method. The structure and morphology of two kinds of nanoparticl...Carbon-supported platinum catalysts were prepared by NaBH4 reduction of metal precursors and the CeO2 nanoparticles were prepared by citric acid sol-gel method. The structure and morphology of two kinds of nanoparticles were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）, respectively. The Pt particles were uniformly dispersed on the carbon surface and showed the rod-like morphology. The CeO2 was spherical in shape. The appropriate amount of CeO2 nanoparticles was added into Pt/C systems to improve activity of the catalysts. Several electrochemical techniques such as cyclic voltammogram （CV）, chronoamperometry （l-t） and electrochemical impedance spectroscopy （EIS） were used to investigate the properties of CeOe-PVC catalysts for methanol electrooxidation in 1 mol/L CH3OH＋0.SH2SO4 aqueous solutions. The results revealed that compared with Pt/C catalysts CeO2-Pt/C exhibited a higher activity and stability for methanol electro-oxidation. Moreover, the effect of CeO2 content on the activity of Pt/C catalysts was discussed in detail.展开更多
The three-dimensional(3D)self-supporting Pt nanoflower catalyst was prepared by using Pt organic compounds as precursors in a low-temperature molten salt system.The obtained Pt nanoflower nanoparticle can reach 400-50...The three-dimensional(3D)self-supporting Pt nanoflower catalyst was prepared by using Pt organic compounds as precursors in a low-temperature molten salt system.The obtained Pt nanoflower nanoparticle can reach 400-500 nm with a face-centered cubic structure,which has the structural characteristics of a loose framework and more exposed active sites.The surfactant-free Pt nanoflower was directly used as methanol electrooxidation reaction(MOR)electrocatalysts without any pretreatment and activated carbon support.The results of electrochemical catalytic oxidation of methanol showed that the Pt nanoflower catalyst exhibit more enhanced electrocatalytic oxidation performance toward methanol compared with the commercial platinum black catalyst.The green and effective method can be developed and expected to enable mass production of fuel cell catalysts.展开更多
基金supported by the National Natural Science Foundation of China (21633008,21673221)the Jilin Province Science and Technology Development Program (20160622037JC,20170203003SF,and 20170520150JH)+1 种基金the Hundred Talents Program of the Chinese Academy of Sciencesthe Recruitment Program of Foreign Experts (WQ20122200077)
文摘Direct methanol fuel cells （DMFCs） are very promising power source for stationary and portable miniatureelectric appliances due to its high efficiency and low emissions of pollutants. As the key material, cata-lysts for both cathode and anode face several problems which hinder the commercialization of DMFCs.In this review, we mainly focus on anode catalysts of DMFCs. The process and mechanism of methanolelectrooxidation on Pt and Pt-based catalysts in acidic medium have been introduced. The influences ofsize effect and morphology on electrocatalytic activity are discussed though whether there is a size effectin MOP, catalyst is under debate. Besides, the non Pt catalysts are also listed to emphasize though Pt isstill deemed as the indispensable element in anode catalyst of DMFCs in acidic medium. Different cata-lyst systems are compared to illustrate the level of research at present. ome debates need to be verifiedwith experimental evidences.
基金the National Natural Science Foundation of China (Grant Nos. 21273058, 21673064, 51802059 and 21503059)China Postdoctoral Science Foundation (Grant Nos. 2018M631938, 2018T110307 and 2017M621284)+1 种基金Heilongjiang Postdoctoral Fund (LBH-Z17074)Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 2019040 and 2019041)
文摘A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.
基金supported by FedDev Ontario through the Applied Research and Commercialization (ARC) Initiative and the Natural Sciences and Engineering Research Council of Canada (NSERC) programMicrobonds, Inc. for additional financial support
文摘Carbon modified TiO_2 nanobelts(TiO_2-C) were synthesized using a hydrothermal growth method,as a support material for palladium(Pd) nanoparticles(Pd/TiO_2-C) to improve the electrocatalytic performance for methanol electrooxidation by comparison to Pd nanoparticles on bare TiO_2 nanobelts(Pd/TiO_2)and activated carbon(Pd/AC). Cyclic voltammetry characterization was conducted with respect to saturated calomel electrode(SCE) in an alkaline methanol solution, and the results indicate that the specific activity of Pd/TiO_2-C is 2.2 times that of Pd/AC and 1.5 times that of Pd/TiO_2. Chronoamperometry results revealed that the TiO_2-C support was comparable in stability to activated carbon, but possesses an enhanced current density for methanol oxidation at a potential of -0.2 V vs. SCE. The current study demonstrates the potential of Pd nanoparticle loaded on hierarchical TiO_2-C nanobelts for electrocatalytic applications such as fuel cells and batteries.
基金Supported by the National Innovative Research Program for Undergraduates,China(No.2010A33039)the Science and Technology Development Program of Jilin Province,China(No.20100420)
文摘Carbon supported Pt（Pt/C） electrocatalysts were prepared with glucose as protection agent and NaBH 4 as reductant.The Pt nanoparticles deposited on carbon support presented reduced size and well dispersity attributed to the protection effect of glucose.Glucose absorbed on the particle surface was readily removed by water washing without leading to agglomeration of the Pt nanoparticles.The as-prepared Pt/C electrocatalysts showed improved mass activity for methanol electrooxidation compared to the catalyst prepared without glucose protection.The improved performance is attributed to the larger electrochemical active surface area thus increased active sites on the Pt/C elctrocatalysts prepared under the protection of glucose.
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 Natural Science Foundation of China(22272148)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Yangzhou University)(KYCX22_3456)。
文摘Direct methanol fuel cells are promising energy-supplying devices for future portable electronics,but the anodic methanol oxidation has been crying out for high-efficiency catalysts.Ruthenium oxide(RuO_(2))exhibits the capacity to improve the catalytic performance of Pt-based materials,while the underlying mechanism is still not clear.Herein,we constructed carbonencapsulated RuO_(2)clusters supported Pt nanoparticles with enhanced catalytic activity and durability towards the methanol oxidation reaction(MOR),and the in-depth mechanism was studied by in-situ infrared absorption spectrum and first-principles computation.The carbon-encapsulated RuO_(2)clusters alleviated the dissolution of metallic Ru in acidic media and regulated the electronic structure of Pt nanoparticles via the electronic metal-support interaction.In-situ attenuated total reflection-surfaceenhanced infrared absorption spectroscopy(ATR-SEIRAS)tracked the intermediates and confirmed the facilitated dissociation of interfacial water on the Pt-RuO_(2)/C at a low potential of 0.56 V,generating active OH species to promote the oxidative removal of CO intermediates and CO_(2)generation.Theoretical calculations further confirmed the weakened CO adsorption energy on Pt-RuO_(2)as well as the decreased reaction energy barrier of the rate-determining CO oxidation step.As a result,the Pt-RuO_(2)/C showed a MOR peak current density of 68.7 mA cm^(-2),which was 1.7 and 2.9 times that of commercial PtRu/C and Pt/C catalysts.Besides,the current density of Pt-RuO_(2)/C reached 10.4 mA cm^(-2)at 0.66 V,about 3.3 and 5.0 times that of commercial PtRu/C and Pt/C catalysts,indicating good catalytic activity at low potentials.The current work contributes some practical and theoretical basis to the development of a novel Pt-Ru electrocatalyst system for energy conversion techniques.
基金This work was supported by National Natural Science Foundation of China （No. 21473111）, Natural Science Foundation of Shaanxi Province （No. 2015JM2043）,and Fundamental Research Funds for the Central Universities （Nos. GK201602002 and GK201503037）.
文摘Nanocrystals of Rh, an important member of the noble metal catalyst family, have wide applications in heterogeneous catalytic reactions. Controlling the morphology of these noble metal nanocrystals has become an effective strategy for improving their catalytic activity and durability. In this work, well-defined Rh nanodendrites with very thin triangular branches as subunits are synthesized using a facile diethylene glycol reduction method, assisted by polyethyleneimine as a complex-forming agent and surfactant. For the first time, the methanol oxidation reaction （MOR） on Rh nanocrystals with a well-defined morphology is investigated using various electrochemical techniques in an alkaline medium. Unexpectedly, the as-prepared Rh nanodendrites, with ultrathin nanosheet subunits, exhibit superior electrocatalytic activity and durability during the MOR in an alkaline medium, indicating that Rh nanocrystals with specific morphology may be highly promising alternatives to Pt electrocatalysts in the MOR in an alkaline medium.
基金This work was supported by the National Natural Science Foundation of China(Nos.51872209 and 51972239)the Key programs for Science and Technology Innovation of Wenzhou(No.2018ZG005).
文摘Platinum based alloys are hereinto the mostly used methanol oxidation catalysts.However,there are limited ways to improve the methanol oxidation reaction(MOR)performance of catalysts in terms of both activity and stability.Herein we developed a simple heat-treatment method to synthesize PtCu_(3)/C intermetallic compound catalyst with lattice compression.The as-prepared PtCu_(3)/C-1000 exhibited high specific activity of 3.23 mA·cm^(-1) and mass activity of 1,200 mA·mgPt^(-1),which is much higher than the PtCu_(3)/C-untreated and commercial Pt/C catalysts,respectively.The XAS and DFT results shows the high activity of the catalyst towards MOR comes from the tightening of the Pt-M bond,which leads to the decrease of Fermi energy level and the make it difficulty in adsorbing carbon intermediates,thus releasing more active sites to promote the improvement of MOR performance.Moreover,the PtCu_(3)/C-1000 shows better stability which is due to the surface-rich Pt prevents Cu from dissolution.
文摘Methanol oxidation on smooth Pt electrode modified with different coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO 2 was calculated from faraday current and ion current of m/z =44. The results show that Ru modified Pt electrode with the coverage of ca . 0 3 has the highest catalytic activity for methanol electrooxidation, i.e. faraday current and the current efficiency of CO 2 at the low potentials reach to the maximum. In addition, Ru loses its co catalytic properties at the high potentials.
基金supported by the National Natural Science Foundation of China(21403125,21403124)the Scientific Research Foundation for the Outstanding Young Scientist of Shandong Province(BS2011NJ009)~~
文摘Fe_2O_3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction（MOR） in an alkaline electrolyte.The catalysts were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,cyclic voltammetry and chronoamperometry.The results show that the presence of Fe_2O_3 in the electrocatalysts can promote the kinetic processes of MOR on Pt,and this promoting effect is related to the morphology of the Fe_2O_3 promoter.The catalyst with Fe_2O_3 nanorods as the promoter（Pt-Fe_2O_3/C-R） exhibits much higher catalytic activity and stability than that with Fe_2O_3 nanoplates as the promoter（Pt-Fe_2O_3/C-P）.The mass activity and specific activity of Pt in a Pt-Fe_2O_3/C-R catalyst are 5.32 A/mgpt and 162.7 A/m^2_（Pt）,respectively,which are approximately 1.67 and 2.04 times those of the Pt-Fe_2O_3/C-P catalyst,and 4.19 and 6.16 times those of a commercial PtRu/C catalyst,respectively.Synergistic effects between Fe_2O_3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement.These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.
文摘In the current study, perovskite type LaFNPs （LaFeO3 nanoparticles） were prepared by a rapid microwave-assisted co-precipitation method and their presence was confirmed by XRD, EDX and SEM techniques. LaFNPs and LaFNPs-CNTs （LaFeO3NPs-carbon nanotubes） nanocomposites were successfully prepared. GC （glassy carbon） electrode was modified with LaFNPs and LaFNPs-CNTs for methanol electrooxidation. The electrocatalytic activity of LaFNPs and LaFNPs-CNTs nanocatalysts toward methanol electrooxidation was examined through cyclic voltammetry and chronoamperometry methods. The effect of some experimental factors such as methanol, LaFNPs amounts, electrolyte concentrations and scan rate was studied. The catalytic activity of LaFNPs-CNTs and LaFNPs nanocatalysts was compared with each other. According to the electrochemical investigations, LaFNPs nanocatalyst had a considerable activity for methanol electrooxidation in comparison to LaFNPs nanocatalyst.
基金supported by the National Basic Research Program of China(2013CB934001)the Natural Science Foundation of Beijing(2051001)the Natural Science Foundation of China(51074011)
文摘A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation （MEO） has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles （PdNPs） with a narrow particle size distribution （3-5 nm） are uni- formly deposited onto the surface of Co304 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst （448 mA/mg Pd）. The dependency of log/against logv reveals that MEO on Pd-CO304 electrode is under a diffusion control. Electrochemical impedance spectroscopy （EIS） measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-CO304 is observed at -0.05 V, which coincides with the potential of MEO peak.
基金Project supported by the National Natural Science Foundation of China (20963009)Gansu Science and Technology Committee (0803RJA005)
文摘Carbon-supported platinum catalysts were prepared by NaBH4 reduction of metal precursors and the CeO2 nanoparticles were prepared by citric acid sol-gel method. The structure and morphology of two kinds of nanoparticles were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）, respectively. The Pt particles were uniformly dispersed on the carbon surface and showed the rod-like morphology. The CeO2 was spherical in shape. The appropriate amount of CeO2 nanoparticles was added into Pt/C systems to improve activity of the catalysts. Several electrochemical techniques such as cyclic voltammogram （CV）, chronoamperometry （l-t） and electrochemical impedance spectroscopy （EIS） were used to investigate the properties of CeOe-PVC catalysts for methanol electrooxidation in 1 mol/L CH3OH＋0.SH2SO4 aqueous solutions. The results revealed that compared with Pt/C catalysts CeO2-Pt/C exhibited a higher activity and stability for methanol electro-oxidation. Moreover, the effect of CeO2 content on the activity of Pt/C catalysts was discussed in detail.
基金funded by the Program of the central government guide local funding projects for scientific and technological development(YDZX20201400001843)Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20220032)+2 种基金Key research and development Project of Shanxi Province(202102090301008)Scientific Research Project of Shanxi Datong University(2020CXZ3)the Natural Science Foundation of Shanxi Province of China(201801D221057).
文摘The three-dimensional(3D)self-supporting Pt nanoflower catalyst was prepared by using Pt organic compounds as precursors in a low-temperature molten salt system.The obtained Pt nanoflower nanoparticle can reach 400-500 nm with a face-centered cubic structure,which has the structural characteristics of a loose framework and more exposed active sites.The surfactant-free Pt nanoflower was directly used as methanol electrooxidation reaction(MOR)electrocatalysts without any pretreatment and activated carbon support.The results of electrochemical catalytic oxidation of methanol showed that the Pt nanoflower catalyst exhibit more enhanced electrocatalytic oxidation performance toward methanol compared with the commercial platinum black catalyst.The green and effective method can be developed and expected to enable mass production of fuel cell catalysts.
