Self-Assembled Ni₃S₂ Nanosheets with Mesoporous Structure Tightly Held on Ni Foam as a Highly Efficient and Long-Term Electrocatalyst for Water Oxidation

Synthesis of highly efficient and stable electrocatalysts for oxygen evolution reaction remains a big challenge. Herein, we rationally designed a novel route, involving hydrothermal electrodeposition of Ni/Zn alloy and in situ electrochemical dealloying followed by sulfuration, to fabricate three-dimensional mesoporous nickel sulfide nanosheets assembled tightly on Ni foam for oxygen evolution reaction. The mesoporous Ni 3 S 2 nanosheets/Ni foam exhibited a highly mesoporous structure with a specific surface area of 60.1 m 2 g –1 and showed a low overpotential of 223 mV at a current density of 10 mA cm –2 with a small Tafel slope of 60.5 mV dec –1; this overpotential is superior to that of IrO 2 /Ni foam. As-prepared Ni 3 S 2 nanosheets/Ni foam achieved a high turnover frequency value of 0.61 mol O 2 s –1 at an overpotential of 500 mV. Impressively, the as-obtained catalyst possessed excellent conductivity and outstanding stability for over 240 h. The superior catalytic property could be ascribed to the rational synthetic process, morphology-controlled mesoporous structure, and highly exposed active sites. This paper presents an efficient route to fabricate porous nanosheets as stable and efficient electrocatalyst for water oxidation.