CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catal...CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.展开更多
Two-electron oxygen reduction reaction(2e-ORR)provides an environmentally friendly direction for the on-site production of hydrogen peroxide(H_(2)O_(2)).Central to this technology is the exploitation of efficient,econ...Two-electron oxygen reduction reaction(2e-ORR)provides an environmentally friendly direction for the on-site production of hydrogen peroxide(H_(2)O_(2)).Central to this technology is the exploitation of efficient,economical,and safe 2e-ORR electrocatalysts.This overview starts with the fundamental chemistry of ORR to highlight the decisive role of adsorbing intermediates on the reaction pathway and activity,followed by a comprehensive survey of the tuning strategies to favor 2e-ORR on traditional precious metals.The latest achievements in designing efficient and selective precious-metal-based single-atom catalysts(SACs)and metal-nitrogen-carbon(M-Nx/C)catalysts,from the aspects of material synthesis,theoretical calculations,and mass transport promotion,are systematically summarized.Brief introductions on the evaluation metrics for 2e-ORR catalysts and the primary reactor designs for cathodic H_(2)O_(2)synthesis are also included.We conclude this review with an outlook on the challenges and direction of efforts to advance electrocatalytic 2e-ORR into realistic H_(2)O_(2)production.展开更多
Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbo...Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed.展开更多
Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell(PEMFC)anode,but are limited by their extreme sensitivity to CO in parts per million(ppm)level,thereby making the use of ultrapur...Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell(PEMFC)anode,but are limited by their extreme sensitivity to CO in parts per million(ppm)level,thereby making the use of ultrapure H_(2)a prerequisite to ensure acceptable performance.Herein,we confront the CO poisoning issue by bringing the Ir/Rh single atom sites to synergistically working with their metallic counterparts.In presence of 1000 ppm CO,the catalyst represents not only undisturbed H_(2)oxidation reaction(HOR)catalytic behavior in electrochemical cell,but also unparalleled peak power density at 643 mW cm^(-2)in single cell,27-fold in mass activity of the best PtRu/C catalysts available.Pre-poisoning experiments and surface-enhanced Raman scattering spectroscopy(SERS)and calculation results in combine suggest the presence of adjacent Ir/Rh single atom sites(SASs)to the nanoparticles(NPs)as the origin for this prominent catalytic behavior.The single sites not only exhibit superb CO oxidation performance by themselves,but can also scavenge the CO adsorbed on approximated NPs via supplying reactive OH*species.We open up a new route here to conquer the formidable CO poisoning issue through single atom and nanoparticle synergistic catalysis,and pave the way towards a more robust PEMFC future.展开更多
The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor stability.As the lattice-oxygen-medi...The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor stability.As the lattice-oxygen-mediated mechanism(LOM)has been identified as the major contributor to the fast performance degradation,impeding lattice oxygen diffusion to inhibit lattice oxygen participation is imperative,yet remains challenging due to the lack of efficient approaches.Herein,we strategically regulate the bonding nature of Ru–O towards suppressed LOM via Ru-based high-entropy oxide(HEO)construction.The lattice disorder in HEOs is believed to increase migration energy barrier of lattice oxygen.As a result,the screened Ti_(23)Nb_(9)Hf_(13)W_(12)Ru_(43)O_(x) exhibits 11.7 times slower lattice oxygen diffusion rate,84%reduction in LOM ratio,and 29 times lifespan extension compared with the state-of-the-art RuO_(2) catalyst.Our work opens up a feasible avenue to constructing stabilized Ru-based OER catalysts towards scalable application.展开更多
In this work,the effect of Nafion ionomer content on the structure and catalytic performance of direct CO polymer electrolyte membrane fuel cell(CO-PEMFC)by using Rh-N-C single-atom catalyst as the anode catalyst laye...In this work,the effect of Nafion ionomer content on the structure and catalytic performance of direct CO polymer electrolyte membrane fuel cell(CO-PEMFC)by using Rh-N-C single-atom catalyst as the anode catalyst layers was studied.The ionic plaque and roughness of the anode catalyst layers increase with the increase of Nafion ionomer content.Furthermore,the contact angle measurement results show that the hydrophilicity of the anode catalyst layers also increases with the increase of Nafion ionomer content.However,when the Nafion ionomer content is too low,the binding between microporous layers,catalyst layers and membrane cannot meet the requirement for either electric conductivity or mass transfer.While Nafion ionomer content increased above 30%,the content of water in anode is difficult to control.Therefore,it was found that AN 30(30%Nafion ionomer content of anode)is the best level to effectively extend the three-phase boundary and improve CO-PEMFCs performance.展开更多
基金Jilin Province Science and Technology Development Program,Grant/Award Numbers:20180101030JC,20190201270JC,20200201001JCNational Natural Science Foundation of China,Grant/Award Numbers:21633008,21673221,21875243,U1601211+1 种基金Research Innovation Fund,Grant/Award Number:DNL202010Special Funds for Guiding Local Scientific and Technological Development by the Central Government,Grant/Award Number:2020JH6/10500021。
文摘CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.
基金the National Natural Science Foundation of China(No.22209102)Natural Science Foundation of Shanxi Province(No.202203021212398).
文摘Two-electron oxygen reduction reaction(2e-ORR)provides an environmentally friendly direction for the on-site production of hydrogen peroxide(H_(2)O_(2)).Central to this technology is the exploitation of efficient,economical,and safe 2e-ORR electrocatalysts.This overview starts with the fundamental chemistry of ORR to highlight the decisive role of adsorbing intermediates on the reaction pathway and activity,followed by a comprehensive survey of the tuning strategies to favor 2e-ORR on traditional precious metals.The latest achievements in designing efficient and selective precious-metal-based single-atom catalysts(SACs)and metal-nitrogen-carbon(M-Nx/C)catalysts,from the aspects of material synthesis,theoretical calculations,and mass transport promotion,are systematically summarized.Brief introductions on the evaluation metrics for 2e-ORR catalysts and the primary reactor designs for cathodic H_(2)O_(2)synthesis are also included.We conclude this review with an outlook on the challenges and direction of efforts to advance electrocatalytic 2e-ORR into realistic H_(2)O_(2)production.
基金supported by the National Key R&D Program of China(grant no.2022YFB4004100)National Natural Science Foundation of China(grant nos.22272161 and 22179126)Jilin Province Science and Technology Development Program(grant no.20230101367JC).
文摘Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed.
基金supported by the National Key Research and Development Program of China(2022YFB4004100)the National Natural Science Foundation of China(U22A20396 and 22209168)+1 种基金the Natural Science Foundation of Anhui Province(2208085UD04)China Postdoctoral Science Foundation(2023M743375)。
文摘Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell(PEMFC)anode,but are limited by their extreme sensitivity to CO in parts per million(ppm)level,thereby making the use of ultrapure H_(2)a prerequisite to ensure acceptable performance.Herein,we confront the CO poisoning issue by bringing the Ir/Rh single atom sites to synergistically working with their metallic counterparts.In presence of 1000 ppm CO,the catalyst represents not only undisturbed H_(2)oxidation reaction(HOR)catalytic behavior in electrochemical cell,but also unparalleled peak power density at 643 mW cm^(-2)in single cell,27-fold in mass activity of the best PtRu/C catalysts available.Pre-poisoning experiments and surface-enhanced Raman scattering spectroscopy(SERS)and calculation results in combine suggest the presence of adjacent Ir/Rh single atom sites(SASs)to the nanoparticles(NPs)as the origin for this prominent catalytic behavior.The single sites not only exhibit superb CO oxidation performance by themselves,but can also scavenge the CO adsorbed on approximated NPs via supplying reactive OH*species.We open up a new route here to conquer the formidable CO poisoning issue through single atom and nanoparticle synergistic catalysis,and pave the way towards a more robust PEMFC future.
基金The authors thank the National Key R&D Program of China(No.2021YFB4000200)the National Natural Science Foundation of China(No.22232004)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA21090400)the Jilin Province Science and Technology Development Program(Nos.20210301008GX,YDZJ202202CXJD011,and 20210502002ZP)for financial support.
文摘The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor stability.As the lattice-oxygen-mediated mechanism(LOM)has been identified as the major contributor to the fast performance degradation,impeding lattice oxygen diffusion to inhibit lattice oxygen participation is imperative,yet remains challenging due to the lack of efficient approaches.Herein,we strategically regulate the bonding nature of Ru–O towards suppressed LOM via Ru-based high-entropy oxide(HEO)construction.The lattice disorder in HEOs is believed to increase migration energy barrier of lattice oxygen.As a result,the screened Ti_(23)Nb_(9)Hf_(13)W_(12)Ru_(43)O_(x) exhibits 11.7 times slower lattice oxygen diffusion rate,84%reduction in LOM ratio,and 29 times lifespan extension compared with the state-of-the-art RuO_(2) catalyst.Our work opens up a feasible avenue to constructing stabilized Ru-based OER catalysts towards scalable application.
基金supported by the National Key Research and Development Program of China (2017YFB0102900)the National Natural Science Foundation of China (21875243, 21633008, 21673221, and U1601211)+3 种基金Jilin Provincial Science and Technology Development Program (20200201001JC, 20190201270JC, and 20180101030JC)supported by the High Performance Computing Center of Jilin University and Jilin ProvinceNetwork and Computing Center of Changchun Institute of Applied Chemistry, Chinese Academy of Sciencessupported by Linglu Instruments (Shanghai) Co., Ltd.
基金National Natural Science Foundation of China(Nos.21633008,21875243,21673221 and U1601211)Science and Technology Development Program of Jilin Province,China(Nos.20200201001JC,20190201270JC and 20180101030JC).
文摘In this work,the effect of Nafion ionomer content on the structure and catalytic performance of direct CO polymer electrolyte membrane fuel cell(CO-PEMFC)by using Rh-N-C single-atom catalyst as the anode catalyst layers was studied.The ionic plaque and roughness of the anode catalyst layers increase with the increase of Nafion ionomer content.Furthermore,the contact angle measurement results show that the hydrophilicity of the anode catalyst layers also increases with the increase of Nafion ionomer content.However,when the Nafion ionomer content is too low,the binding between microporous layers,catalyst layers and membrane cannot meet the requirement for either electric conductivity or mass transfer.While Nafion ionomer content increased above 30%,the content of water in anode is difficult to control.Therefore,it was found that AN 30(30%Nafion ionomer content of anode)is the best level to effectively extend the three-phase boundary and improve CO-PEMFCs performance.