Fabrication of (Ni,Co)0.85Se nanosheet arrays derived from layered double hydroxides toward largely enhanced overall water splitting

Abstract

The development of bifunctional electrocatalysts towards both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is promising for highly efficient overall water splitting to meet sustainable energy demands. In this work, a bifunctional electrocatalyst based on ultrathin transition metal selenide nanosheet arrays (NSAs) for both the OER and HER has been designed and synthesized. The as-obtained (Ni,Co)_0.85Se NSAs give excellent electrochemical activity and high long-term stability under alkaline conditions, with a low overpotential of 169 mV at a current density of 10 mA cm⁻² for the HER and an overpotential of 287 mV at a current density of 20 mA cm⁻² for the OER. Furthermore, (Ni,Co)_0.85Se NSAs exhibit superior performance and durability toward overall water splitting with a cell voltage as low as 1.65 V at a current density of 10 mA cm⁻² and a long-term stability of 50 h, which makes (Ni,Co)_0.85Se NSAs a promising alternative for electrochemical hydrogen generation.