Elucidating the Facet-Dependent Oxygen Reduction Reaction Performance of Cu Nanosheet over N-O co-Doped Graphene

Developing highly efficient noble-metal-free catalysts for oxygen reduction reaction (ORR) is critical for the widespread commercialization of metal-air batteries. Facet engineering provides an effective strategy to optimize the catalysts' activity, while the controlling facet orientation in non-precious metals remains challenging. Here we show a substrate-induced growth strategy to synthesize copper nanosheets with specific (200) and (111) facet orientations over nitrogen/oxygen co-doped graphene (N/O-C) via chemical vapor deposition (Cu(200)@N/O-C and Cu(111)@N/O-C), revealing a distinct facet-dependent activity for ORR. It clarifies the substrate oxygen coordination promotes preferential Cu(200) growth under moderate deposition, whereas excess vapor drives thermodynamically favored Cu(111) formation. Theoretical and experimental analyses demonstrate Cu(200) facet in N/O-C optimizes the adsorption energies of ORR intermediates and lowers the reaction barrier for the rate-determining step to outperform the Cu(111), which also exhibits better activity compared to commercial Pt/C. When integrated into zinc-air batteries, Cu(200)@N/O-C delivers a power density of 222.5 mW·cm^-2 and stable operation for over 1000 hours, highlighting the potential of facet-engineering on earth-abundant Cu for next-generation energy storage.