Rational manipulation of 3D hierarchical oxygenated nickel tungsten selenide nanosheet as the efficient bifunctional electrocatalyst for overall water splitting

The development of a bifunctional hierarchical nanostructure catalyst with high activity, low cost, excellent reversibility, and binder-free is an emerging key demand in industrial application for overall water splitting. In this work, a new strategy was employed for the rational design of 3D hierarchical oxygenated nickel tungsten selenide on conductive nickel foam substrate (O–Ni1−xWxSe2/NF) by a low-cost hydrothermal process, followed by a partial controlled-selenization process. Owing to the enriched oxygenated intermediates and abundant active sites with nanoporous networks, the optimal O–Ni0.5W0.5Se2 hierarchical nanostructure shows excellent catalytic activities for hydrogen evolution and oxygen evolution reactions, which exhibit a low overpotential of ∼ 109 and 238 mV at 20 mA cm−2, with remarkable durability. Most significantly, the O-Ni0.5W0.5Se2||O-Ni0.5W0.5Se2 electrolyzer required a small cell voltage of ∼ 1.56 V at 10 mA cm−2. The present study suggests a new strategy for designing highly active hierarchical 3D oxygenated enriched metal selenide as a durable bifunctional electrocatalyst.