Hierarchical nickel cobalt sulfide nanosheet arrays supported on CuO/Cu hybrid foams as a rationally designed core–shell dendrite electrocatalyst for an efficient oxygen evolution reaction

Abstract

Designing highly efficient, stable and low-cost electrocatalysts for the oxygen evolution reaction (OER) plays a key role in producing hydrogen via the electrolysis of water. Herein, we have reported a facile and manageable approach to fabricate a 3D steady core–shell dendrite electrocatalyst with a nickel cobalt sulfide porous nanosheet as an outer layer and a CuO nanowire as an inner core supported by a Cu foam for OER. Benefiting from the advantages of this unique 3D core–shell structure that endows abundant active sites, abundant interfacial heterostructures, high-speed electron transport network and short diffusion paths for releasing O₂ bubbles, the electrocatalyst displays outstanding OER performance with low overpotentials of only 240, 289, and 309 mV at the current densities of 10, 50, and 100 mA cm⁻², respectively, and high stability over 48 h at a current density of 50 mA cm⁻² in alkaline media. The excellent properties of the synthesized 3D dendrite-like catalyst for OER can pave the way for large-scale practical water electrolysis.