Nickel–Cobalt Diselenide Nanosheets Supported on Copper Nanowire Arrays for Synergistic Electrocatalytic Oxygen Evolution

Rational nanoarchitecture design and smart hybridization of bespoke catalysts can greatly accelerate the sluggish kinetics of oxygen evolution reaction (OER) in electrochemical water splitting. Here, hierarchical NixCo1−xSe2 porous nanosheets are synthesized on Cu nanowire arrays (CNW) to fabricate highly efficient core/shell structure integrated OER electrode. Highly conductive CNW arrays are first obtained via the reduction of the pre‐prepared CuO nanowire arrays. NixCo1−x precursor nanosheets are then grown on CNW via hydrothermal route, and the following selenylation led to in situ formation of NixCo1−xSe2 porous nanosheet. In the integrated electrode, the highly conductive CNW core can realize efficient electron transport. The hierarchical core/shell nanoarray structure can provide abundant catalytic active sites and more void space to release gas bubbles, and meanwhile prevent the underneath Cu nanowire core from oxidation. The synergistic effects of optimized components and smart structure of the integrated electrode afford a remarkable OER activity with a low potential of 1.423 V versus reversible hydrogen electrode (RHE) at 10 mA cm−2 current density, a small Tafel of 58 mV dec−1, and excellent stability in alkaline electrolyte. The present fabrication approach offers a direction in the design and synthesis of integrated catalysts on conductive substrates for promising electrocatalytic applications.