Surface-Restructured Core/Shell NiO@Co3O4 Nanocomposites as Efficient Catalysts for the Oxygen Evolution Reaction

Developing electrocatalysts with rich active sites is highly demanded for an oxygen evolution reaction (OER) with the virtues of high efficiency and cheap cost. Herein, we prepared unique oxygen vacancy-rich core/shell NiO@Co3O4 nanocomposites decorated with Co3O4 nanosheets as efficient OER electrocatalysts. First, NiO@Co3O4 nanocomposites were synthesized through a rationally designed stepwise coprecipitation process followed by controlled heating treatment. With a facile NaBH4 reduction treatment, Co3O4 nanosheets were in situ formed on the surface of NiO@Co3O4 nanocomposites, introducing more oxygen vacancies and edge sites simultaneously. These surface-restructured core/shell NiO@Co3O4 nanocomposites exhibited significantly improved activity as OER electrocatalysts possessing a low overpotential (290 mV at 10 mA cm–2) and a small Tafel slope (68 mV dec–1) in 1 M KOH media. Our work offers an effective strategy to prepare core/shell metal oxide nanocomposites with adjustable surface structures for electrocatalysis.