Well-defined heteronuclear bimetallic atomic clusters:Emerging electrocatalysts

The low-temperature electrocatalytic conversion of small molecules has been recognized as a sustainable and environmentally benign strategy for the production of high-value chemicals and transportable fuels.Developing efficient electrocatalysts is the core of these electrocatalytic processes.Recently,single atom catalysts(SACs)have achieved great success in various electrocatalytic reactions with predominant catalytic activity such as hydrogen evolution reaction(HER)[1]and oxygen reduction reaction(ORR)[2].However,they encounter considerable challenges for recently emerging complex reactions where multiple reactants,intermediates,and products are involved.The incompetence of SACs towards such complex reactions mainly comes from the single active centers,which cannot be adapted for simultaneous adsorption and coupling of multiple reactants,thus leading to unsatisfactory catalytic performance.To overcome this challenge,researchers have proposed to construct the catalysts with multiple metal atoms as the catalytically active center while keeping them atomically isolated like SACs,for example heterogeneous bimetallic atomic clusters(HBACs).Compared with homogeneous metal clusters containing only one metal element,HBACs have two designable metal centers,offering various specific catalytic sites for simultaneously targeting different elementary steps in electrocatalytic reactions and harnessing the synergistic effect from two catalytic centers.In addition,the orbital interactions between different metal atoms open up the possibility for regulating the electronic structure of the specific metal active sites,thus improving their intrinsic catalytic activity.Thus,such well-defined HBACs hold great potential for improved catalytic activity,selectivity,and durability for complex electrocatalytic reactions compared with SACs and nanoparticle-based heterogeneous catalysts.