摘要：The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely ***,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic ***,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon *** from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V ***,far exceeding those of some representative SACs with a ultra-high metal *** work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.

摘要：The rational design and construction of hierarchically porous nanostructure for oxygen reduction reaction (ORR) electrocatalysts is crucial to facilitate the exposure of accessible active sites and promote the mass/electron transfer under the gas-solid-liquid triple-phase condition. Herein, an ingenious method through the pyrolysis of creative polyvinylimidazole coordination with Zn/Fe salt precursors is developed to fabricate hierarchically porous Fe-N-doped carbon framework as efficient ORR electrocatalyst. The volatilization of Zn species combined with the nanoscale Kirkendall effect of Fe dopants during the pyrolysis build the hierarchical micro-, meso-, and macroporous nanostructure with a high specific surface area (1,586 m^(2)·g^(−1)), which provide sufficient exposed active sites and multiscale mass/charge transport channels. The optimized electrocatalyst exhibits superior ORR activity and robust stability in both alkaline and acidic electrolytes. The Zn-air battery fabricated by such attractive electrocatalyst as air cathode displays a higher peak power density than that of Pt/C-based Zn-air battery, suggesting the great potential of this electrocatalyst for Zn-air batteries.

摘要：The oxygen reduction reaction （ORR） is essential in research pertaining to life science and energy. In applications, platinum-based catalysts give ideal reactivity, but, in practice, are often subject to high costs and poor stability. Some costefficient transition metal oxides have exhibited excellent ORR reactivity, but the stability and durability of such alternative catalyst materials pose serious challenges. Here, we present a facile method to fabricate uniform CoxOy nanoparticles and embed them into N-doped carbon, which results in a composite of extraordinary stability and durability, while maintaining its high reactivity. The half-wave potential shows a negative shift of only 21 mV after 10,000 cycles, only one third of that observed for Pt/C （63 mV）. Furthermore, after 100,000 s testing at a constant potential, the current decreases by only 17%, significantly less than for Pt/C （35%）. The exceptional stability and durability results from the system architecture, which comprises a thin carbon shell that prevents agglomeration of the CoxOy nanoparticles and their detaching from the substrate.

摘要：The performance of proton exchange membrane fuel cells depends heavily on the oxygen reduction reaction(ORR)at the cathode,for which platinum-based catalysts are currently the *** high cost and limited availability of platinum have driven the search for alternative *** FeN4 single-atom catalysts have shown promising potential,their ORR activity needs to be further *** contrast,dual-atom catalysts(DACs)offer not only higher metal loading but also the ability to break the ORR scaling ***,the diverse local structures and tunable coordination environments of DACs create a vast chemical space,making large-scale computational screening *** this study,we developed a graph neural network(GNN)-based framework to predict the ORR activity of Fe-based DACs,effectively addressing the challenges posed by variations in local catalyst *** model,trained on a dataset of 180 catalysts,accurately predicted the Gibbs free energy of ORR intermediates and overpotentials,and identified 32 DACs with superior catalytic activity compared to FeN4 *** approach not only advances the design of high-performance DACs,but also offers a powerful computational tool that can significantly reduce the time and cost of catalyst development,thereby accelerating the commercialization of fuel cell technologies.

摘要：The quest for low‐cost yet efficient non‐Pt electrocatalysts for the oxygen reduction reaction(ORR)has become one of the main focuses of research in the field of catalysis,which has implications for the development of the next generation of greener fuel ***,we comprehensively describe the'big picture'of recent advances made in the rational design of ORR electrocatalysts,including molecule‐based,metal‐oxide‐based,metal‐nanomaterial‐based and two‐dimensional *** metals can fabricate molecular electrocatalysts with N4‐macrocycles such as porphyrin‐class compounds and the so‐formed M-N-C active centre plays a crucial role in determining the catalytic performances towards the ***‐IV and‐V Transition metal oxides represent another class of promising alternative of Pt‐based catalysts for the ORR which catalytic activity largely depends on the surface structure and the introduction of surface *** advances in synthesis of metallic nanoparticles(NPs)allow for precise control over particle sizes and shapes and the crystalline facets exposed to enhance the ORR performance of ***‐dimensional materials such as functionalized grapheme or MoS2are emerging as novel electrocatalysts for the *** review covers various aspects towards the design of future ORR electrocatalysts,including the catalytic performance,stability,durability and *** novel electrocatalysts even surpass commercial Pt/C systems,demonstrating their potential to be alternatives in industrial *** the encouraging progress,challenges,which are also described,remain to be overcome before the real‐world application of novel ORR electrocatalysts.

摘要：The special electronic characteristics and high atom usage efficiency of metal-nitrogen-carbon(M-N-C)materials have made them extremely attractive for oxygen reduction reactions(ORRs).However,it is inevitable that hydrogen peroxide(H_(2)O_(2))will be formed via the two-electron pathway in ***,the Cu nanoparticles(NPs)have been encapsulated into Ni doped hollow mesoporous carbon spheres(Ni-HMCS)to reduce the generation of H_(2)O_(2)in *** tests confirm that the introduction of Cu NPs improves the ORR performance *** obtained Cu/Ni-HMCS exhibits a half-wave potential of 0.82 V *** hydrogen electrode and a limited current density of 5.5 mA cm^(-2),which is comparable with the commercial Pt/***,Cu/Ni-HMCS has been used in Zn-air battery,demonstrating a high power density of 161 mW cm^(-2)and a long-term recharge capability(50 h at 5 mA cm^(-2)).The theoretical calculation proposes a tandem catalysis pathway for Cu/Ni multi-sites catalysis,that is,H_(2)O_(2)released from the Ni-N_(4)and Cu-N_(4)sites migrates to the Cu(111)face,on which the captive H_(2)O_(2)is further reduced to H_(2)*** work demonstrates an interesting tandem catalytic pathway of dual-metal multi-sites for ORR,which provides an insight into the development of effective fuel cell electrocatalysts.

摘要：Proton exchange membrane fuel cells(PEMFCs)are considered ideal energy‐conversion devices because of their environmentally friendly nature and high theoretical energy ***,cathodic polarization,which is a result of the sluggish oxygen reduction reaction(ORR)kinetics,is a significant source of energy loss and reduces fuel cell ***,the need to use Pt in commercial Pt/C cathodes has restricted their large‐scale application in fuel cells because of its high cost and poor ***,improvements in the activity and durability of Pt‐based catalyst are required to reduce the amount of Pt required and,thus,costs,while increasing the ORR rate and fuel cell power density and promoting widespread PEMFC *** recent years,atomically ordered Pt‐based intermetallic nanocrystals have received tremendous attention owing to their excellent activity and stability for the ***,in this review,we first introduce the formation of intermetallic compounds from the perspective of thermodynamics and kinetics to lay a theoretical foundation for the design of these *** addition,optimization strategies for Pt‐based ordered intermetallic catalysts are summarized in terms of the catalyst composition,size,and ***,we conclude with a discussion of the current challenges and future prospects of Pt‐based ordered *** review is designed to help readers gain insights into the recent developments in and rational design of Pt‐based intermetallic nanocrystals for the ORR and encourage research that will enable the commercialization of PEMFCs.

摘要：A novel pure and N-doped waved-graphene electro-catalyst with various wavelengths for oxygen reduction reaction（ORR） is explored in acid medium based on the firstprinciples calculations. The associative and dissociative mechanism are both explored from the O_2 adsorption to the H_2 O formation step by step, from which the dissociative mechanism is likely the only way with an effective 4e-process. Furthermore, a very favorable and effective mechanism is proposed for the ORR process, which may provide a guideline on the design of new non-metal electro-catalysts.

摘要：Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption *** high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce *** this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained *** optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good *** results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw *** results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized ***,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.

摘要：Nonprecious metal-based oxygen reduction reaction(ORR)electrocatalysts with high efficiency in both alkaline and acidic media are being intensively studied for the purpose of replacing expensive Pt-based catalysts;however,it is still a challenge to achieve superior ORR performances,especially in acidic ***,by pyrolysis of mixed precursors of diammonium phosphate,melamine and hemin,we prepared a nanocomposite catalyst(denoted as FeP@PGL)composed of nitrogen-doped carbon nanosheets with embedded FeP nanoparticles(NPs),which were encapsulated by in-situ formed phosphorus-doped graphene *** is found that phosphorous was preferentially doped in the coating layers on FeP NPs,instead of in the carbon *** FeP@PGL catalyst exhibited excellent ORR performance,with the onset and half-wave potential up to 1.01 and 0.90 V *** reversible hydrogen electrode(RHE)in alkaline media,and0.95 and 0.81 V *** in acidic media,*** thorough microscopy and spectroscopy characterizations,the interfacial charge transfer between the encapsulated FeP NPs and P-doped graphene layers was identified,and the local work function of the catalyst surface was also reduced by the interfacial *** interfacial synergy between the encapsulated FeP and phosphorus-doped graphene layers was essential to enhance the ORR *** study not only demonstrates the promising ORR properties of the encapsulated-FeP-based nanocomposite catalyst,but also provides direct evidence of the interfacial charge transfer effect and its role in ORR process.