Vacancies and interfaces engineering of core–shell heterostuctured NiCoP/NiO as trifunctional electrocatalysts for overall water splitting and zinc-air batteries

The electronic structures and properties of electrocatalysts, which depend on the physicochemical structure and metallic element components, could significantly affect their electrocatalytic performance and their future applications in Zn-air battery (ZAB) and overall water splitting (OWS). Here, by combining vacancies and heterogeneous interfacial engineering, three-dimensional (3D) core–shell NiCoP/NiO heterostructures with dominated oxygen vacancies have been controllably in-situ grown on carbon cloth for using as highly efficient electrocatalysts toward hydrogen and oxygen electrochemical reactions. Theoretical calculation and electrochemical results manifest that the hybridization of NiCoP core with NiO shell produces a strong synergistic electronic coupling effect. The oxygen vacancy can enable the emergence of new electronic states within the band gap, crossing the Fermi levels of the two spin components and optimizing the local electronic structure. Besides, the hierarchical core–shell NiCoP/NiO nanoarrays also endow the catalysts with multiple exposed active sites, faster mass transfer behavior, optimized electronic strutures and improved electrochemical performance during ZAB and OWS applications.