Enhancing the stability of Pt-based electrocatalysts for the sluggish cathodic oxygen reduction reaction(ORR)is critical for proton exchange membrane fuel cells(PEMFCs).Herein,high-entropy intermetallic(HEI)L1_(2)-Pt(...Enhancing the stability of Pt-based electrocatalysts for the sluggish cathodic oxygen reduction reaction(ORR)is critical for proton exchange membrane fuel cells(PEMFCs).Herein,high-entropy intermetallic(HEI)L1_(2)-Pt(FeCoNiCuZn)3is designed for durable ORR catalysis.Benefiting from the unique HEI structure and the enhanced intermetallic phase stability,Pt(FeCoNiCuZn)3/C nanoparticles demonstrate significantly improved stability over Pt/C and PtCu_(3)/C catalysts.The Pt(FeCoNiCuZn)3/C exhibits a negligible decay of the half-wave potential during 30,000 potential cycles from 0.6 to 1.0 V,whereas Pt/C and PtCu_(3)/C are negatively shifted by 46 and 36 m V,respectively.Even after 10,000 cycles at potential up to 1.5 V,the mass activity of Pt(FeCoNiCuZn)3/C still shows~70%retention.As evidenced by the structural characterizations,the HEI structure of Pt(FeCoNiCuZn)3/C is well maintained,while PtCu_(3)/C nanoparticles undergo severe Cu leaching and particle growth.In addition,when assembled Pt(FeCoNiCuZn)3/C as the cathode in high-temperature PEMFC of 160℃,the H_(2)-O_(2)fuel cell delivers almost no degradation even after operating for 150 h,demonstrating the potential for fuel cell applications.This work provides a facile design strategy for the development of high-performance ultrastable electrocatalysts.展开更多
Redox flow batteries have received wide attention for electrochemical energy conversion and storage devices due to their specific advantage of uncoupled power and energy devices,and therefore potentially to reduce the...Redox flow batteries have received wide attention for electrochemical energy conversion and storage devices due to their specific advantage of uncoupled power and energy devices,and therefore potentially to reduce the capital costs of energy storage.Terrific structural features of polyoxometalates exhibit unique advantages in redox flow batteries,such as,stable chemical properties,multi-electron reaction,good redox reversibility,low permeability,etc,which furnishes a novel perspective for settling various problems of redox flow batteries.This was a comprehensive and critical review of this type of batteries,focusing mainly on the chemistry of polyoxometalate electrolyte materials and introducing a systematic classification.Finally,challenges and perspectives of polyoxometalate electrolyte materials and polyoxometalate redox flow batteries are discussed.展开更多
Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fu...Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).展开更多
Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row tr...Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row transition metal atoms have been coordinated with N atoms on the graphite layers of carbon nanotubes via a M-N_(4)-C configuration(MSA/CNT,M=Fe,Co and Ni).The HzOR over the three single atom catalysts follows a predominant 4-electron reaction pathway to emit N_(2) and a negligible 1-electron pathway to emit trace of NH3,while their electrocatalytic activity for HzOR is dominated by the absorption energy of N2H4 on them.Furthermore,FeSA/CNT reverses the passivation effect on Fe/C and shows superior performance than CoSA/CNT and NiSA/CNT with a recorded high mass activity for HzOR due to the higher electronic charge of Fe over Co and Ni in the M-N_(4)-C configuration and the lowest absorption energy of N_(2)H_(4) on FeSA/CNT among the three MSA/CNT catalysts.展开更多
Elevation of operational temperatures of polymer electrolyte membrane fuel cells(PEMFCs)has been demonstrated with phosphoric acid-doped polybenzimidazole(PA/PBI)membranes.The technical perspective of the technology i...Elevation of operational temperatures of polymer electrolyte membrane fuel cells(PEMFCs)has been demonstrated with phosphoric acid-doped polybenzimidazole(PA/PBI)membranes.The technical perspective of the technology is simplified construction and operation with possible integration with,e.g.,methanol reformers.Toward this target,significant efforts have been made to develop acid-base polymer membranes,inorganic proton conductors,and organic-inorganic composite materials.This report is devoted to updating the recent progress of the development particularly of acid-doped PBI,phosphate-based solid inorganic proton conductors,and their composite electrolytes.Long-term stability of PBI membranes has been well documented,however,at typical temperatures of 160℃.Inorganic proton-conducting materials,e.g.,alkali metal dihydrogen phosphates,heteropolyacids,tetravalent metal pyrophosphates,and phosphosilicates,exhibit significant proton conductivity at temperatures of up to 300℃ but have so far found limited applications in the form of thin films.Composite membranes of PBI and phosphates,particularly in situ formed phosphosilicates in the polymer matrix,showed exceptionally stable conductivity at temperatures well above 200℃.Fuel cell tests at up to 260℃ are reported operational with good tolerance of up to 16%CO in hydrogen,fast kinetics for direct methanol oxidation,and feasibility of nonprecious metal catalysts.The prospect and future exploration of new proton conductors based on phosphate immobilization and fuel cell technologies at temperatures above 200℃ are discussed.展开更多
A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell (MEC). The strategy for fast biocathode cultivation was demonstrated....A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell (MEC). The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H2-full atmosphere to enrich Ha-utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction (HER) kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L-1 to 0.5 mol· L-1 and/or by decreasing the cathode potential from -0.9 V to - 1.3 V vs. a saturated calomel electrode (SCE). Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H+ can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m3. m 3. d1 with a current density of 951.6 A. m-3 was obtained using the biocathode MEC under a cathode potential of - 1.3 V vs. SCE and 0.4 mol· L-1 bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.展开更多
High-temperature proton-exchange membrane fuel cells(HT-PEMFCs)have shown a broad prospect of applications due to the enhanced reaction kinetics and simplified supporting system.However,the proton conductor,phosphoric...High-temperature proton-exchange membrane fuel cells(HT-PEMFCs)have shown a broad prospect of applications due to the enhanced reaction kinetics and simplified supporting system.However,the proton conductor,phosphoric acid,tends to poison the active sites of Pt,resulting in high Pt consumption.Herein,Pt nanoparticles anchored on SiO_(2)-modified carbon nanotubes(CNT@SiO_(2)-Pt)are prepared as high-performance cathode catalysts for HT-PEMFCs.The SiO_(2)in CNT@SiO_(2)-Pt can induce the adsorption of phosphoric acid transferring from Pt active sites in the catalytic layer,avoiding the poisoning of the Pt,and the phosphate fixed by SiO_(2)provide a high-speed proton conduction highway for oxygen reduction reactions.Accordingly,The CNT@SiO_(2)-Pt cathode achieve superior power density of 765 mW cm^(−2)(160℃)and 1,061 mW cm^(−2)(220℃)due to the rapid proton-coupled electron process and outstanding stability in HT-PEMFCs.This result provides a new road to resolve the phosphate poisoning for the commercialization of HT-PEMFCs.展开更多
基金supported by the National Natural Science Foundation(22279036)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)。
文摘Enhancing the stability of Pt-based electrocatalysts for the sluggish cathodic oxygen reduction reaction(ORR)is critical for proton exchange membrane fuel cells(PEMFCs).Herein,high-entropy intermetallic(HEI)L1_(2)-Pt(FeCoNiCuZn)3is designed for durable ORR catalysis.Benefiting from the unique HEI structure and the enhanced intermetallic phase stability,Pt(FeCoNiCuZn)3/C nanoparticles demonstrate significantly improved stability over Pt/C and PtCu_(3)/C catalysts.The Pt(FeCoNiCuZn)3/C exhibits a negligible decay of the half-wave potential during 30,000 potential cycles from 0.6 to 1.0 V,whereas Pt/C and PtCu_(3)/C are negatively shifted by 46 and 36 m V,respectively.Even after 10,000 cycles at potential up to 1.5 V,the mass activity of Pt(FeCoNiCuZn)3/C still shows~70%retention.As evidenced by the structural characterizations,the HEI structure of Pt(FeCoNiCuZn)3/C is well maintained,while PtCu_(3)/C nanoparticles undergo severe Cu leaching and particle growth.In addition,when assembled Pt(FeCoNiCuZn)3/C as the cathode in high-temperature PEMFC of 160℃,the H_(2)-O_(2)fuel cell delivers almost no degradation even after operating for 150 h,demonstrating the potential for fuel cell applications.This work provides a facile design strategy for the development of high-performance ultrastable electrocatalysts.
基金supported by the National Natural Science Foundation of China(No.22178012,21722601)China Postdoctoral Science Foundation(No.2019M660389).
文摘Redox flow batteries have received wide attention for electrochemical energy conversion and storage devices due to their specific advantage of uncoupled power and energy devices,and therefore potentially to reduce the capital costs of energy storage.Terrific structural features of polyoxometalates exhibit unique advantages in redox flow batteries,such as,stable chemical properties,multi-electron reaction,good redox reversibility,low permeability,etc,which furnishes a novel perspective for settling various problems of redox flow batteries.This was a comprehensive and critical review of this type of batteries,focusing mainly on the chemistry of polyoxometalate electrolyte materials and introducing a systematic classification.Finally,challenges and perspectives of polyoxometalate electrolyte materials and polyoxometalate redox flow batteries are discussed.
基金financialy supported by the National Key R&D Program of China(No.2018YFB1502303)the National Natural Science Foundation of China(No.21722601,U19A2017)China Postdoctoral Science Foundation(No.2019M660389)。
文摘Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).
基金Project supported by Beijing Natural Science Foundation(No.2194076)the National Natural Science Foundation of China(Nos.21908001,21872003,and U19A2017)the Fundamental Research Funds for the Central Universities。
文摘Elucidating the reaction mechanism of hydrazine oxidation reaction(HzOR)over carbon-based catalysts is highly propitious for the rational design of novel electrocatalysts for HzOR.In present work,isolated first-row transition metal atoms have been coordinated with N atoms on the graphite layers of carbon nanotubes via a M-N_(4)-C configuration(MSA/CNT,M=Fe,Co and Ni).The HzOR over the three single atom catalysts follows a predominant 4-electron reaction pathway to emit N_(2) and a negligible 1-electron pathway to emit trace of NH3,while their electrocatalytic activity for HzOR is dominated by the absorption energy of N2H4 on them.Furthermore,FeSA/CNT reverses the passivation effect on Fe/C and shows superior performance than CoSA/CNT and NiSA/CNT with a recorded high mass activity for HzOR due to the higher electronic charge of Fe over Co and Ni in the M-N_(4)-C configuration and the lowest absorption energy of N_(2)H_(4) on FeSA/CNT among the three MSA/CNT catalysts.
基金This project was supported by the Beijing Natural Science Foundation(No.2194076)the National Natural Science Foundation of China(Nos.21908001,21722601,and 21576007)+3 种基金the National Key R&D Program of China(No.2018YFA0702003)the Beijing Municipal Science and Technology Project(Z181100004518004)the Fundamental Research Funds for the Central Universities,the Australian Research Council(DP180100731 and DP180100568)the EUDP program(COBRA-drive)of Denmark.
文摘Elevation of operational temperatures of polymer electrolyte membrane fuel cells(PEMFCs)has been demonstrated with phosphoric acid-doped polybenzimidazole(PA/PBI)membranes.The technical perspective of the technology is simplified construction and operation with possible integration with,e.g.,methanol reformers.Toward this target,significant efforts have been made to develop acid-base polymer membranes,inorganic proton conductors,and organic-inorganic composite materials.This report is devoted to updating the recent progress of the development particularly of acid-doped PBI,phosphate-based solid inorganic proton conductors,and their composite electrolytes.Long-term stability of PBI membranes has been well documented,however,at typical temperatures of 160℃.Inorganic proton-conducting materials,e.g.,alkali metal dihydrogen phosphates,heteropolyacids,tetravalent metal pyrophosphates,and phosphosilicates,exhibit significant proton conductivity at temperatures of up to 300℃ but have so far found limited applications in the form of thin films.Composite membranes of PBI and phosphates,particularly in situ formed phosphosilicates in the polymer matrix,showed exceptionally stable conductivity at temperatures well above 200℃.Fuel cell tests at up to 260℃ are reported operational with good tolerance of up to 16%CO in hydrogen,fast kinetics for direct methanol oxidation,and feasibility of nonprecious metal catalysts.The prospect and future exploration of new proton conductors based on phosphate immobilization and fuel cell technologies at temperatures above 200℃ are discussed.
基金This work was financial supported by grants from the National Natural Science Foundation of China (Grant Nos. 51108014, 21373022, 21073010, 21003007 and Ul137602), National Major Research Program (No. 2011CB935700), Beijing Nova Program (Z1311090004 13008), Fundamental Research Funds for the Central Universities (YWF- 10-03-021), Research Fund for the Doctoral Program of Higher Education of China (20111102120045) and Program for New Century Excellent Talents in University.
文摘A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell (MEC). The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H2-full atmosphere to enrich Ha-utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction (HER) kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L-1 to 0.5 mol· L-1 and/or by decreasing the cathode potential from -0.9 V to - 1.3 V vs. a saturated calomel electrode (SCE). Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H+ can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m3. m 3. d1 with a current density of 951.6 A. m-3 was obtained using the biocathode MEC under a cathode potential of - 1.3 V vs. SCE and 0.4 mol· L-1 bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.
基金supported by the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(21825201,U19A2017)+3 种基金the Provincial Natural Science Foundation of Hunan(2019GK2031,2016TP1009,2020JJ5045)China Postdoctoral Science Foundation(2020M682541)the Science and Technology Innovation Program of Hunan Province,China(2020RC2020)Changsha Municipal Natural Science Foundation(kq2007009)。
基金supported by National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(21902047,21825201,U19A2017)+1 种基金the Provincial Natural Science Foundation of Hunan(2016TP1009 and 2020JJ5045)Hunan Graduate Education Innovation Project and Professional Ability Improvement Project(CX20200445)。
文摘High-temperature proton-exchange membrane fuel cells(HT-PEMFCs)have shown a broad prospect of applications due to the enhanced reaction kinetics and simplified supporting system.However,the proton conductor,phosphoric acid,tends to poison the active sites of Pt,resulting in high Pt consumption.Herein,Pt nanoparticles anchored on SiO_(2)-modified carbon nanotubes(CNT@SiO_(2)-Pt)are prepared as high-performance cathode catalysts for HT-PEMFCs.The SiO_(2)in CNT@SiO_(2)-Pt can induce the adsorption of phosphoric acid transferring from Pt active sites in the catalytic layer,avoiding the poisoning of the Pt,and the phosphate fixed by SiO_(2)provide a high-speed proton conduction highway for oxygen reduction reactions.Accordingly,The CNT@SiO_(2)-Pt cathode achieve superior power density of 765 mW cm^(−2)(160℃)and 1,061 mW cm^(−2)(220℃)due to the rapid proton-coupled electron process and outstanding stability in HT-PEMFCs.This result provides a new road to resolve the phosphate poisoning for the commercialization of HT-PEMFCs.