Engineering Long-Lasting Electron Buffer of Nanoalloys toward Overall Water Splitting of Nitrides

Interstitial transition metal catalysts hold promise as nonprecious metal bifunctional catalysts for water electrolysis. However, they still suffer from inferior activity and stability in industrial applications. Here, we report an unexpected collective effect between NiCo nanoalloy and molybdenum nitride on the Ni foam substrate (Mo 2 N@NiCo/NF). Distinct from the conventional promoting effect of single-atom systems, the collective properties of localized nanosized NiCo particles in Mo 2 N@NiCo/NF comprise differently weighted geometric and electronic interactions, resulting in remarkably enhanced hydrogen evolution reaction (HER) activity for Mo 2 N active sites in alkaline environments, relative to Pt/C@NF. Combining electrocatalytic kinetics, detailed characterization, and theoretical simulation, the nanospatially located NiCo nanoalloy inside one-dimensional Mo 2 N nanoarrays serves as a collective electron buffer with enhanced redox-shuttling properties, fulfilling the bifunctional catalytic activities for overall water and simulated seawater splitting with excellent durability (200 h at 50 or 100 mA cm –2 ). Our findings underline the importance of a collective effect to design efficient bifunctional metal electrocatalysts.