Coupling Single-Ni-Atom with Ni-Co Alloy Nanoparticle for Synergistically Enhanced Oxygen Reduction Reaction

A unique hollow carbon structure madeup of single-Ni-atomand NiCo alloy nanoparticles is reported for electrochemical oxygenreduction in both alkaline and acidic electrolytes. Developing nonprecious metal-based oxygen reduction reaction(ORR)electrocatalysts with superior activity and durability is crucialfor commercializing proton-exchange membrane (PEM) fuel cells. Herein,we report a metal-organic framework (MOF)-derived unique N-dopedhollow carbon structure (NiCo/hNC), comprising of atomically dispersedsingle-Ni-atom (NiN4) and small NiCo alloy nanoparticles(NPs), for highly efficient and durable ORR catalysis in both alkalineand acidic electrolytes. Density functional theory (DFT) calculationsreveal the strong coupling between NiN4 and NiCo NPs, favoringthe direct 4e(-) transfer ORR process by lengtheningthe adsorbed O-O bond. Moreover, NiCo/hNC as a cathode electrodein PEM fuel cells delivered a stable performance. Our findings notonly furnish the fundamental understanding of the structure-activityrelationship but also shed light on designing advanced ORR catalysts.

Automated summary

A unique hollow carbon structure made up of single-Ni-atom and NiCo alloy nanoparticles is reported as an efficient electrocatalyst for oxygen reduction reactions in both alkaline and acidic electrolytes. The structure, derived from a metal-organic framework, exhibits superior activity and durability due to the strong coupling between the single-Ni-atom and the NiCo alloy nanoparticles. Furthermore, the carbon structure shows stable performance as a cathode electrode in proton-exchange membrane fuel cells.