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

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.