Spinel-type oxygen-incorporated Ni3+ self-doped Ni3S4 ultrathin nanosheets for highly efficient and stable oxygen evolution electrocatalysis.

Spinel-type structured materials have attracted considerable attention and been regarded as promising alternative catalysts for oxygen evolution reaction (OER). However, the regulation of catalytically active octahedral sites in spinel structure to realize high activity and good stability for OER electrocatalysis is still a great challenge. Herein, we propose a self-doping strategy to boost OER performance of spinel-type Ni3S4 enriched high valence Ni3+ as active sites. By sacrificing Ni-based metal-organic framework, the ultrathin Ni3S4 manosheets are topologically grown on conductive Ni foam substrate and realize the simultaneous Ni3+ self-doping and surface oxygen incorporation during in situ sulfidation conversion process. These compositional and structural characteristics endow it with enhanced adsorption binding strength, enabling the highly efficient OER. As a result, the Ni3S4/NF exhibits excellent activity and outstanding stability toward OER electrocatalysis in alkaline medium, which only demands an ultralow overpotential of 266 mV to deliver a current density of 10 mA cm-2 and manifests the stable OER process for at least 75 h. Moreover, when used as an effective overall water splitting electrolyzer, the Ni3S4/NF achieves a current density of 10 mA cm-2 at only 1.638 V with good long-term stability.