Inspired by molecular catalysts,researchers developed atomically precise nitrogen-coordinated single or dual metal sites imbedded in graphitized carbon(M-N-C)to fully utilize metallic sites for 02activation.These cata...Inspired by molecular catalysts,researchers developed atomically precise nitrogen-coordinated single or dual metal sites imbedded in graphitized carbon(M-N-C)to fully utilize metallic sites for 02activation.These catalysts performed remarkably well in the electrocatalytic oxygen reduction reaction(ORR)due to their distinct coordination and electrical structures,Nonetheless,their maximum efficacy in practical applications has yet to be achieved.This agenda identifies tailoring the coordination environment,spin states,intersite distance,and metal-metal interaction as innovative approaches to regulate the ORR performance of these catalysts.However,it is necessary to undertake a precise assessment of these methodologies and the knowledge obtained to be implemented in the design of future M-N-C catalysts for ORR.Therefore,this review aims to analyze recent progress in M-N-C ORR catalysts,emphasizing their innovative engineering with aspects such as alteration in intersite distance,metal-metal interaction,coordination environment,and spin states.Additionally,we critically discuss how to logically monitor the atomic structure,local coordination,spin,and electronic states of M-N-C catalysts to modulate their ORR activity.We have also highlighted the challenges associated with M-N-C catalysts and proposed suggestions for their future design and fabrication.展开更多
Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses...Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses challenges to the commercial viability of PEMFCs.Non-platinum group metal(non-PGM)alternatives,like nitrogen-coordinated transition metals in atomic dispersion(M–N–C catalysts),show significant potential.This work presents a comparative study of two distinct sets of Fe–N–C materials,prepared by pyrolyzing hybrid composites of polyaniline(PANI)and iron(Ⅱ)chloride on a hard template.One set uses bipyridine(BPy)as an additional nitrogen source and iron ligand,offering an innovative approach.The findings reveal that the choice of pyrolysis temperature and atmosphere influences the catalyst properties.The use of ammonia in pyrolysis emerges as a crucial parameter for promoting atomic dispersion of iron,as well as increasing surface area and porosity.The optimal catalyst,prepared using BPy and ammonia,exhibits a half-wave potential of 0.834 V in 0.5 M H_(2)SO_(4)(catalyst loading of 0.6 mg cm^(-2)),a mass activity exceeding 3 A g^(-1)and high stability in acidic electrolyte,positioning it as a promising non-PGM structure in the field.展开更多
Hybrid electrolyte lithium-air batteries(HELABs)face challenges such as the high cathode overpotential,cycling instability,and catalyst degradation,limiting their widespread use in practical applications.This study em...Hybrid electrolyte lithium-air batteries(HELABs)face challenges such as the high cathode overpotential,cycling instability,and catalyst degradation,limiting their widespread use in practical applications.This study employs density functional theory(DFT)to analyze the oxygen reduction reaction(ORR)free energy profile,overpotential,and adsorption energy of two-dimensional Ti_(3)C_(2)T_(x) as a cathode catalyst.The optimal oxygen adsorption sites on Ti_(3)C_(2)T_(x) surfaces are identified,and the charge transfer,band structure,density of states,and bonding characteristics after oxygen adsorption are quantitatively analyzed.Results suggest that Ti_(3)C_(2)T_(x) exhibits low overpotentials when used as a HELAB cathode electrocatalyst,with oxygen preferentially adsorbing at the top and bridge sites of Ti_(3)C_(2) and Ti_(3)C_(2)F2,respectively.These findings offer valuable insights for the application of MXenes in HELABs.展开更多
The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxyg...The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.展开更多
Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-bas...Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.展开更多
Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bif...Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs.Atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis.In this work,general principles for designing atomically dispersed M-N-C are reviewed.Then,strategies aiming at enhancing the bifunctional catalytic activity and stability are presented.Finally,the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined.It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.展开更多
Metal-organic frameworks(MOFs) have been widely used in oxygen reduction reaction(ORR) of fuel cells and metal-air batteries, attributed to their unique structures and compositions. Recently, the preparation of transi...Metal-organic frameworks(MOFs) have been widely used in oxygen reduction reaction(ORR) of fuel cells and metal-air batteries, attributed to their unique structures and compositions. Recently, the preparation of transition-metallic single-atom electrocatalysts(TM-SACs) using MOFs as precursors or templates has made great progress. Herein, the development history of SACs prepared based on MOFs and their characterization are overviewed firstly, and then several strategies are summarized for preparing TM-SACs using MOFs and further modification. Finally, the challenges and opportunities confronted by TM-SACs are fully discussed. Consequently, our work can guide the realization of TM-SACs abundant with high activity, high loading and high stability.展开更多
metal oxide electronic interactions in composite electrocatalysts have a considerable impact on their catalytic capability.In this study,we successfully synthesized an electrocatalytic material composed of MoO_(3)/C s...metal oxide electronic interactions in composite electrocatalysts have a considerable impact on their catalytic capability.In this study,we successfully synthesized an electrocatalytic material composed of MoO_(3)/C speciessupported Pd nanoparticles(Pd-MoO_(3)/C)using a convenient hydrothermal method,which exhibited excellent catalytic activities for both ethanol oxidation and oxygen reduction in KOH media.The specific activity of PdMoO_(3)/C toward ethanol oxidation with MoO_(3)loading(40wt%)was~2.6 times greater than that for the commercial Pd/C(10 wt%)with the same Pd content.In particular,the activity could effectively hold up to~60%of its maximum activity after 500-cycle tests,demonstrating improved cyclical stability.Notably,the fast electron transfer kinetics toward oxygen reduction for Pd-MoO_(3)/C(40%)were also comparable to those of commercial Pt/C(20 wt%)catalysts.These superior electrochemical features are primarily derived from the stronger electronic coupling between Pd and MoO_(3)through charge transfer,which can supply more active centers and improve the anti-poisoning ability.Meanwhile,the MoO_(3)species in the Pd-MoO_(3)/C composite may provide additional benefits in terms of electrical conductivity and dispersion.展开更多
Oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) are the key reactions in numerous renewable energy devices. Unlike conventional powdered catalysts, self-supported catalysts are extensively employed i...Oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) are the key reactions in numerous renewable energy devices. Unlike conventional powdered catalysts, self-supported catalysts are extensively employed in oxygen electrocatalysis because of the enhanced electron-transfer rate, high specific surface area, and superior mechanical flexibility. Among the self-supported conductive substrates, carbon fiber usually exhibits several distinctive advantages, such as a straightforward preparation process, relatively low cost, good stability, and excellent conductivity. Against this background,carbon fiber-based self-supported electrocatalysts have been widely applied and studied in oxygen electrocatalysis, indicating a promising development direction in oxygen electrocatalyst research.Thus, it is essential to offer an overall summary of the research progress in this field to facilitate its subsequent development. Taking the regulatory mechanisms and modification methods as a starting point, this review comprehensively summarizes recent research on carbon fiber-based self-supported electrocatalysts in recent years. Firstly, a brief overview of the synthesis methods and regulatory mechanisms of carbon fiber-based self-supported electrocatalysts is given. Furthermore, the view also highlights the modification methods and research progress of self-supported electrocatalysts synthesized on carbon fiber-based substrates in recent years in terms of different dopant atoms. Finally, the prospects for the application of self-supported electrocatalysts based on carbon fiber in oxygen electrocatalysis and the possible future directions of their development are presented. This review summarizes recent developments and applications of self-supported bi-functional electrocatalysts with carbon fiber-based materials as the conducting substrate in oxygen electrocatalysis. It also lays a robust scientific foundation for the subsequent reasonable design of highly effective carbon fiber-based self-supported electrocatalysts.展开更多
The construction of efficient oxygen reduction and oxygen evolution reaction(ORR/OER)bifunctional electrocatalysts is crucial for rechargeable zinc–air batteries.Hierarchical mesoporous N-doped carbon(HMNC)structures...The construction of efficient oxygen reduction and oxygen evolution reaction(ORR/OER)bifunctional electrocatalysts is crucial for rechargeable zinc–air batteries.Hierarchical mesoporous N-doped carbon(HMNC)structures with superior catalytic activities are illustrious candidates for the ORR/OER to substitute precious metal(Pt)-based catalysts.In this study,an optimal HMNC(abbr.NDC-800)with uniform rich-defect active sites was prepared by selection of an eligible Fe complex precursor.The NDC-800 catalyst had excellent ORR activity with a high half wave potential(E_(1/2))of 0.88 V,and an amazing ORR/OER bifunctional performance involving a low potential gap(ΔE)of 0.76 V,which surpasses that of the benchmark Pt/C catalyst.As a rechargeable zinc–air battery catalyst,it has a large power density of 186.12 mW cm^(−2),a high specific capacity up to 630 mA h gZn^(−1),and an excellent cycling stability of 60 h(120 cycles)at 10 mA cm^(−2).Density functional theory(DFT)calculations indicate that the effective ORR/OER bifunctional activities can be attributed to its hierarchical mesoporous structure,which can afford sufficient exposed active sites and rich defects to synergistically promote the formation of OH−intermediates,and reduce the free energy(ΔG).展开更多
The oxygen reduction reaction(ORR)is a crucial process in Zn-air systems,and the catalyst plays a significant role in this reaction.However,reported catalysts often suffer from poor durability and stability during the...The oxygen reduction reaction(ORR)is a crucial process in Zn-air systems,and the catalyst plays a significant role in this reaction.However,reported catalysts often suffer from poor durability and stability during the ORR process.Herein,we synthesized La-Fe bimetallic nanoparticles encapsulated in a N-doped porous carbon dodecahedron(La-Fe/NC)originated from ZIF-8 by a simple direct carbonization.The La-Fe/NC catalyst had a numerous mesopores and dendritic outer layer generated by carbon nanotubes(CNTs),forming a high conductivity network that helped to optimize electron transfer and mass transport in the ORR process.The effect of different doping transition metals and metal ratios on the ORR activity of Zn-air batteries was investigated.In alkaline media,the La-Fe/NC showed the highest ORR catalytic activity,with a half-wave potential(E_(1/2))of 0.879 V(vs.RHE,Pt/C 0.845 V).After 5000 cycles,the E_(1/2)of the La-Fe/NC catalyst only decreased by 7 m V,and its performance in stability tests and methanol tolerance tests was superior to Pt/C.When used as the air electrode in a Zn-air battery,the La-Fe/NC catalyst demonstrated an excellent specific capacity of 755 m Ah/g and a peak power density of179.8 m W/cm~2.The results provide important insights for the development of high-performance Zn-air batteries and new directions for the design of ORR catalysts.展开更多
It is vital to search for efficient and stable oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)electrocatalysts for the development of metal–air batteries.Herein,we systematically investigated a serie...It is vital to search for efficient and stable oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)electrocatalysts for the development of metal–air batteries.Herein,we systematically investigated a series of TMN_(x)O_(4−x)-HTC(TM=Fe,Co,Ni,Ru,Rh,Pd,Ir and Pt;x=0–4;HTC=hexatribenzocyclyne)analogs of two-dimensional(2D)electrically conductive metal–organic frameworks(MOFs)as potential electrocatalysts for the OER and ORR by using density functional theory calculations.The calculated results exhibit good thermodynamic and electrochemical stabilities of the designed TMN_(x)O_(4−x)-HTC.The OER and ORR catalytic activity of the designed catalyst is governed by the interaction strength between the intermediates and the catalyst,and this interaction can be tuned by adjusting TM atoms and the local coordination number of N/O atoms.CoN_(3)O_(1)-HTC is found to be the best OER catalyst with an overpotential η^(OER) of 0.29 V,and RhN_(2)O_(2)-HTC exhibits the lowest ORR overpotentialηORR of 0.20 V.Importantly,RhO_(4)-HTC,RhN_(2)O_(2)-HTC and CoN1O_(3)-HTC are predicted as efficient bifunctional catalysts for the OER and ORR.Moreover,the kinetics simulation verifies the four-electron ORR pathway with high activity and selectivity toward H_(2)O production.The results not only contribute to designing and searching for efficient OER and ORR electrocatalysts but shed light on the opportunities to explore electrochemical applications based on 2D MOF materials.展开更多
Zn-air batteries(ZABs)have been widely studied due to their high theoretical energy density,low cost,and high safety.However,the lack of efficient bifunctional electrocatalysts toward both the oxygen reduction reactio...Zn-air batteries(ZABs)have been widely studied due to their high theoretical energy density,low cost,and high safety.However,the lack of efficient bifunctional electrocatalysts toward both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)hinders their large-scale application.Herein,a dendritic NiS_(2)@Co-N-C/CNF nanoarchitecture is proposed.展开更多
Developing low-cost and highly efficient oxygen electrocatalysts for both the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)has become one important issue recently due to the sluggish kinetics of the...Developing low-cost and highly efficient oxygen electrocatalysts for both the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)has become one important issue recently due to the sluggish kinetics of these two reactions,which require high overpotentials and thus high energy input.Perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts for oxygen electrocatalysis in alkaline media.In this work,an IrO_(2)-incorporated La_(0.8)Sr_(0.2)MnO_(3) composite has been developed as a novel bifunctional oxygen electrocatalyst using a polymer-assisted approach with a subsequent wet impregnation-calcination method.Due to the synergistic effect between the high ORR activity of La_(0.8)Sr_(0.2)MnO_(3) and the good OER activity of IrO_(2) as well as the improved electrochemically active surface area,the electrocatalytic activities of the composite for both the OER and ORR have been improved,compared with those of the pristine La_(0.8)Sr_(0.2)MnO_(3)(ΔE=1.043 V),resulting in its enhanced bifunctionality(ΔE=0.652 V)as an oxygen catalyst in alkaline solution,which is also superior to the reported stateof-the-art electrocatalysts.The stability test shows that after 1000 cycles of cyclic voltammetry(CV),there is only 15 mV positive shift for achieving a current density of 10 mA cm−2 in the OER and 17 mV negative shift to reach a current density of−1 mA cm^(−2) in the ORR,which indicates the good stability of the electrocatalyst(5 wt%IrO_(2) incorporated La_(0.8)Sr_(0.2)MnO_(3))in alkaline solution.Our study not only reports a new composite material as a bifunctional oxygen electrocatalyst,but also opens a new avenue to develop novel perovskite oxide-based electrocatalysts with enhanced bifunctional electrocatalytic activities.展开更多
MOF-templated nitrogen-doped porous carbon materials(NPCs)have been prepared by employing the previously reported MOF,[(CH_(3))_(2)NH_(2)]^(6)[Ni(H_(2)O)_(6)]_(3){Ni_(6)(η^(6)-TATAT)4(H_(2)O)_(12)},as a precursor,whi...MOF-templated nitrogen-doped porous carbon materials(NPCs)have been prepared by employing the previously reported MOF,[(CH_(3))_(2)NH_(2)]^(6)[Ni(H_(2)O)_(6)]_(3){Ni_(6)(η^(6)-TATAT)4(H_(2)O)_(12)},as a precursor,which can act as efficient electrocatalysts for oxygen reduction reactions(ORRs).The carbonized MOF acts as the carbon source,and urea is employed as an additional nitrogen source.The urea modified carbon materials,carbonized at 800℃,900℃ and 1000℃ under Ar atmosphere,all show electrocatalytic activity for ORRs;the material carbonized at 900℃ exhibits a more appropriate nitrogen content,robust pore structure and an excellent degree of graphitization.In alkaline media,NPC-900 exhibits superior catalytic activity(the onset and half-wave potentials are-0.06 V and-0.23 V vs.Ag/AgCl,respectively),excellent long-term durability and outstanding methanol tolerance compared with the commercial Pt/C catalyst.展开更多
基金supported by the Research Fund for International Scientists(RFIS-Grant numbers:52150410410)National Natural Science Foundation of Chinathe Deanship of Scientific Research and Graduate Studies at King Khalid University for funding this research work through Large Research Project under the grant number RGP2/121/1445.
文摘Inspired by molecular catalysts,researchers developed atomically precise nitrogen-coordinated single or dual metal sites imbedded in graphitized carbon(M-N-C)to fully utilize metallic sites for 02activation.These catalysts performed remarkably well in the electrocatalytic oxygen reduction reaction(ORR)due to their distinct coordination and electrical structures,Nonetheless,their maximum efficacy in practical applications has yet to be achieved.This agenda identifies tailoring the coordination environment,spin states,intersite distance,and metal-metal interaction as innovative approaches to regulate the ORR performance of these catalysts.However,it is necessary to undertake a precise assessment of these methodologies and the knowledge obtained to be implemented in the design of future M-N-C catalysts for ORR.Therefore,this review aims to analyze recent progress in M-N-C ORR catalysts,emphasizing their innovative engineering with aspects such as alteration in intersite distance,metal-metal interaction,coordination environment,and spin states.Additionally,we critically discuss how to logically monitor the atomic structure,local coordination,spin,and electronic states of M-N-C catalysts to modulate their ORR activity.We have also highlighted the challenges associated with M-N-C catalysts and proposed suggestions for their future design and fabrication.
基金funding from the Hellenic Foundation for Research and Innovation(HFRI)under grant agreement No 3655.
文摘Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses challenges to the commercial viability of PEMFCs.Non-platinum group metal(non-PGM)alternatives,like nitrogen-coordinated transition metals in atomic dispersion(M–N–C catalysts),show significant potential.This work presents a comparative study of two distinct sets of Fe–N–C materials,prepared by pyrolyzing hybrid composites of polyaniline(PANI)and iron(Ⅱ)chloride on a hard template.One set uses bipyridine(BPy)as an additional nitrogen source and iron ligand,offering an innovative approach.The findings reveal that the choice of pyrolysis temperature and atmosphere influences the catalyst properties.The use of ammonia in pyrolysis emerges as a crucial parameter for promoting atomic dispersion of iron,as well as increasing surface area and porosity.The optimal catalyst,prepared using BPy and ammonia,exhibits a half-wave potential of 0.834 V in 0.5 M H_(2)SO_(4)(catalyst loading of 0.6 mg cm^(-2)),a mass activity exceeding 3 A g^(-1)and high stability in acidic electrolyte,positioning it as a promising non-PGM structure in the field.
文摘Hybrid electrolyte lithium-air batteries(HELABs)face challenges such as the high cathode overpotential,cycling instability,and catalyst degradation,limiting their widespread use in practical applications.This study employs density functional theory(DFT)to analyze the oxygen reduction reaction(ORR)free energy profile,overpotential,and adsorption energy of two-dimensional Ti_(3)C_(2)T_(x) as a cathode catalyst.The optimal oxygen adsorption sites on Ti_(3)C_(2)T_(x) surfaces are identified,and the charge transfer,band structure,density of states,and bonding characteristics after oxygen adsorption are quantitatively analyzed.Results suggest that Ti_(3)C_(2)T_(x) exhibits low overpotentials when used as a HELAB cathode electrocatalyst,with oxygen preferentially adsorbing at the top and bridge sites of Ti_(3)C_(2) and Ti_(3)C_(2)F2,respectively.These findings offer valuable insights for the application of MXenes in HELABs.
基金supported by the National Natural Science Foundation of China(21306119)the Key Research and Development Projects in Sichuan Province(2017GZ0397,2017CC0017)+1 种基金the Science and Technology Project of Chengdu(2015-HM01-00531-SF)the Outstanding Young Scientist Foundation of Sichuan University(2013SCU04A23)
文摘The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.
基金financially supported by the National Natural Science Foundation of China (No.52172058)。
文摘Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.
基金This work is supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)Centre Québéco is sur les Materiaux Fonctionnels(CQMF),Fonds de Recherche du Québec-Nature et Technologies(FRQNT)+2 种基金Institut National de la Recherche Scientifique(INRS)This work is also supported by the National Natural Science Foundation of China(21972017)the“Scientific and Technical Innovation Action Plan”Hong Kong,Macao and Taiwan Science&Technology Cooperation Project of Shanghai Science and Technology Committee(19160760600).F.Dong gratefully acknowledges scholarships from the China Scholarship Council(CSC).
文摘Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs.Atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis.In this work,general principles for designing atomically dispersed M-N-C are reviewed.Then,strategies aiming at enhancing the bifunctional catalytic activity and stability are presented.Finally,the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined.It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.
基金supported by the National Natural Science Foundation of China(51872115,51932003)the 2020 International Cooperation Project of the Department of Science and Technology of Jilin Province(20200801001GH)+3 种基金the Program for the Development of Science and Technology of Jilin Province(20190201309JC)the Jilin Province/Jilin University coConstruction Project-Funds for New Materials(SXGJSF2017-3,Branch-2/440050316A36)the Project for Self-innovation Capability Construction of Jilin Province Development and Reform Commission(2021C026)the Fundamental Research Funds for the Central Universities JLU,and “Double-First Class”Discipline for Materials Science&Engineering。
文摘Metal-organic frameworks(MOFs) have been widely used in oxygen reduction reaction(ORR) of fuel cells and metal-air batteries, attributed to their unique structures and compositions. Recently, the preparation of transition-metallic single-atom electrocatalysts(TM-SACs) using MOFs as precursors or templates has made great progress. Herein, the development history of SACs prepared based on MOFs and their characterization are overviewed firstly, and then several strategies are summarized for preparing TM-SACs using MOFs and further modification. Finally, the challenges and opportunities confronted by TM-SACs are fully discussed. Consequently, our work can guide the realization of TM-SACs abundant with high activity, high loading and high stability.
基金financially supported by the Natural Science Foundation of Shanxi Province(No.201901D111277)the National Natural Science Foundation of China(No.21571119)+1 种基金the Graduate Science and Technology Innovation Project Foundation of Shanxi Normal University(No.2021DCXM71)the Program for New Century Excellent Talents in University(No.NCET-12-1035)。
文摘metal oxide electronic interactions in composite electrocatalysts have a considerable impact on their catalytic capability.In this study,we successfully synthesized an electrocatalytic material composed of MoO_(3)/C speciessupported Pd nanoparticles(Pd-MoO_(3)/C)using a convenient hydrothermal method,which exhibited excellent catalytic activities for both ethanol oxidation and oxygen reduction in KOH media.The specific activity of PdMoO_(3)/C toward ethanol oxidation with MoO_(3)loading(40wt%)was~2.6 times greater than that for the commercial Pd/C(10 wt%)with the same Pd content.In particular,the activity could effectively hold up to~60%of its maximum activity after 500-cycle tests,demonstrating improved cyclical stability.Notably,the fast electron transfer kinetics toward oxygen reduction for Pd-MoO_(3)/C(40%)were also comparable to those of commercial Pt/C(20 wt%)catalysts.These superior electrochemical features are primarily derived from the stronger electronic coupling between Pd and MoO_(3)through charge transfer,which can supply more active centers and improve the anti-poisoning ability.Meanwhile,the MoO_(3)species in the Pd-MoO_(3)/C composite may provide additional benefits in terms of electrical conductivity and dispersion.
基金Tianjin Natural Science Foundation (23JCYBJC00660)Tianjin Enterprise Science and Technology Commissioner Project (23YDTPJC00490)+2 种基金National Natural Science Foundation of China (52203066, 51973157, 61904123)China Postdoctoral Science Foundation Grant (2023M742135)State Key Laboratory of Membrane and Membrane Separation, Tiangong University。
文摘Oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) are the key reactions in numerous renewable energy devices. Unlike conventional powdered catalysts, self-supported catalysts are extensively employed in oxygen electrocatalysis because of the enhanced electron-transfer rate, high specific surface area, and superior mechanical flexibility. Among the self-supported conductive substrates, carbon fiber usually exhibits several distinctive advantages, such as a straightforward preparation process, relatively low cost, good stability, and excellent conductivity. Against this background,carbon fiber-based self-supported electrocatalysts have been widely applied and studied in oxygen electrocatalysis, indicating a promising development direction in oxygen electrocatalyst research.Thus, it is essential to offer an overall summary of the research progress in this field to facilitate its subsequent development. Taking the regulatory mechanisms and modification methods as a starting point, this review comprehensively summarizes recent research on carbon fiber-based self-supported electrocatalysts in recent years. Firstly, a brief overview of the synthesis methods and regulatory mechanisms of carbon fiber-based self-supported electrocatalysts is given. Furthermore, the view also highlights the modification methods and research progress of self-supported electrocatalysts synthesized on carbon fiber-based substrates in recent years in terms of different dopant atoms. Finally, the prospects for the application of self-supported electrocatalysts based on carbon fiber in oxygen electrocatalysis and the possible future directions of their development are presented. This review summarizes recent developments and applications of self-supported bi-functional electrocatalysts with carbon fiber-based materials as the conducting substrate in oxygen electrocatalysis. It also lays a robust scientific foundation for the subsequent reasonable design of highly effective carbon fiber-based self-supported electrocatalysts.
基金supported by the National Natural Science Foundation of China(21771095 and 22071135)the Natural Science Foundation of Shandong Province(ZR2023MB002,ZR2021MB114,ZR2021MB073 and ZR2017JL013)the Youth Innovation Team of Shandong Colleges and Universities(2019KJC027).
文摘The construction of efficient oxygen reduction and oxygen evolution reaction(ORR/OER)bifunctional electrocatalysts is crucial for rechargeable zinc–air batteries.Hierarchical mesoporous N-doped carbon(HMNC)structures with superior catalytic activities are illustrious candidates for the ORR/OER to substitute precious metal(Pt)-based catalysts.In this study,an optimal HMNC(abbr.NDC-800)with uniform rich-defect active sites was prepared by selection of an eligible Fe complex precursor.The NDC-800 catalyst had excellent ORR activity with a high half wave potential(E_(1/2))of 0.88 V,and an amazing ORR/OER bifunctional performance involving a low potential gap(ΔE)of 0.76 V,which surpasses that of the benchmark Pt/C catalyst.As a rechargeable zinc–air battery catalyst,it has a large power density of 186.12 mW cm^(−2),a high specific capacity up to 630 mA h gZn^(−1),and an excellent cycling stability of 60 h(120 cycles)at 10 mA cm^(−2).Density functional theory(DFT)calculations indicate that the effective ORR/OER bifunctional activities can be attributed to its hierarchical mesoporous structure,which can afford sufficient exposed active sites and rich defects to synergistically promote the formation of OH−intermediates,and reduce the free energy(ΔG).
基金supported by the National Natural Science Foundation of China(No.22278291)the Natural Science Foundation of Shanxi Province(Nos.202203021211145 and 202303021221257)+1 种基金the National Key Research and Development(R&D)Program of China(No.2020YFB1505803)the Key Research and Development(R&D)Projects of Shanxi Province(No.202102070301018)。
文摘The oxygen reduction reaction(ORR)is a crucial process in Zn-air systems,and the catalyst plays a significant role in this reaction.However,reported catalysts often suffer from poor durability and stability during the ORR process.Herein,we synthesized La-Fe bimetallic nanoparticles encapsulated in a N-doped porous carbon dodecahedron(La-Fe/NC)originated from ZIF-8 by a simple direct carbonization.The La-Fe/NC catalyst had a numerous mesopores and dendritic outer layer generated by carbon nanotubes(CNTs),forming a high conductivity network that helped to optimize electron transfer and mass transport in the ORR process.The effect of different doping transition metals and metal ratios on the ORR activity of Zn-air batteries was investigated.In alkaline media,the La-Fe/NC showed the highest ORR catalytic activity,with a half-wave potential(E_(1/2))of 0.879 V(vs.RHE,Pt/C 0.845 V).After 5000 cycles,the E_(1/2)of the La-Fe/NC catalyst only decreased by 7 m V,and its performance in stability tests and methanol tolerance tests was superior to Pt/C.When used as the air electrode in a Zn-air battery,the La-Fe/NC catalyst demonstrated an excellent specific capacity of 755 m Ah/g and a peak power density of179.8 m W/cm~2.The results provide important insights for the development of high-performance Zn-air batteries and new directions for the design of ORR catalysts.
基金supported by the National Natural Science Foundation of China(22102167 and U21A20317).
文摘It is vital to search for efficient and stable oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)electrocatalysts for the development of metal–air batteries.Herein,we systematically investigated a series of TMN_(x)O_(4−x)-HTC(TM=Fe,Co,Ni,Ru,Rh,Pd,Ir and Pt;x=0–4;HTC=hexatribenzocyclyne)analogs of two-dimensional(2D)electrically conductive metal–organic frameworks(MOFs)as potential electrocatalysts for the OER and ORR by using density functional theory calculations.The calculated results exhibit good thermodynamic and electrochemical stabilities of the designed TMN_(x)O_(4−x)-HTC.The OER and ORR catalytic activity of the designed catalyst is governed by the interaction strength between the intermediates and the catalyst,and this interaction can be tuned by adjusting TM atoms and the local coordination number of N/O atoms.CoN_(3)O_(1)-HTC is found to be the best OER catalyst with an overpotential η^(OER) of 0.29 V,and RhN_(2)O_(2)-HTC exhibits the lowest ORR overpotentialηORR of 0.20 V.Importantly,RhO_(4)-HTC,RhN_(2)O_(2)-HTC and CoN1O_(3)-HTC are predicted as efficient bifunctional catalysts for the OER and ORR.Moreover,the kinetics simulation verifies the four-electron ORR pathway with high activity and selectivity toward H_(2)O production.The results not only contribute to designing and searching for efficient OER and ORR electrocatalysts but shed light on the opportunities to explore electrochemical applications based on 2D MOF materials.
基金supported by the National Natural Science Foundation of China(no.91961119)the Natural Science Foundation of Tianjin(no.S20YB26121).
文摘Zn-air batteries(ZABs)have been widely studied due to their high theoretical energy density,low cost,and high safety.However,the lack of efficient bifunctional electrocatalysts toward both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)hinders their large-scale application.Herein,a dendritic NiS_(2)@Co-N-C/CNF nanoarchitecture is proposed.
基金support from USDA National Institute of Food and Agriculture,HSI Collaboration:Integrating Food Science/Engineering and Education Network(IFSEEN,award number:2015-38422-24059)supported by the Idaho National Laboratory Directed Research and Development Program under DOE Idaho Operations Office Contract DE-AC07-05ID14517.
文摘Developing low-cost and highly efficient oxygen electrocatalysts for both the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)has become one important issue recently due to the sluggish kinetics of these two reactions,which require high overpotentials and thus high energy input.Perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts for oxygen electrocatalysis in alkaline media.In this work,an IrO_(2)-incorporated La_(0.8)Sr_(0.2)MnO_(3) composite has been developed as a novel bifunctional oxygen electrocatalyst using a polymer-assisted approach with a subsequent wet impregnation-calcination method.Due to the synergistic effect between the high ORR activity of La_(0.8)Sr_(0.2)MnO_(3) and the good OER activity of IrO_(2) as well as the improved electrochemically active surface area,the electrocatalytic activities of the composite for both the OER and ORR have been improved,compared with those of the pristine La_(0.8)Sr_(0.2)MnO_(3)(ΔE=1.043 V),resulting in its enhanced bifunctionality(ΔE=0.652 V)as an oxygen catalyst in alkaline solution,which is also superior to the reported stateof-the-art electrocatalysts.The stability test shows that after 1000 cycles of cyclic voltammetry(CV),there is only 15 mV positive shift for achieving a current density of 10 mA cm−2 in the OER and 17 mV negative shift to reach a current density of−1 mA cm^(−2) in the ORR,which indicates the good stability of the electrocatalyst(5 wt%IrO_(2) incorporated La_(0.8)Sr_(0.2)MnO_(3))in alkaline solution.Our study not only reports a new composite material as a bifunctional oxygen electrocatalyst,but also opens a new avenue to develop novel perovskite oxide-based electrocatalysts with enhanced bifunctional electrocatalytic activities.
基金supported by the National Natural Science Foundation of China[grant number:21501084,21671090,21271096].
文摘MOF-templated nitrogen-doped porous carbon materials(NPCs)have been prepared by employing the previously reported MOF,[(CH_(3))_(2)NH_(2)]^(6)[Ni(H_(2)O)_(6)]_(3){Ni_(6)(η^(6)-TATAT)4(H_(2)O)_(12)},as a precursor,which can act as efficient electrocatalysts for oxygen reduction reactions(ORRs).The carbonized MOF acts as the carbon source,and urea is employed as an additional nitrogen source.The urea modified carbon materials,carbonized at 800℃,900℃ and 1000℃ under Ar atmosphere,all show electrocatalytic activity for ORRs;the material carbonized at 900℃ exhibits a more appropriate nitrogen content,robust pore structure and an excellent degree of graphitization.In alkaline media,NPC-900 exhibits superior catalytic activity(the onset and half-wave potentials are-0.06 V and-0.23 V vs.Ag/AgCl,respectively),excellent long-term durability and outstanding methanol tolerance compared with the commercial Pt/C catalyst.
