Autogenous growth of highly active bifunctional Ni–Fe2B nanosheet arrays toward efficient overall water splitting

Abstract

Developing an effective and low-cost bifunctional electrocatalyst for both OER and HER to achieve overall water splitting is remaining a challenge to meet the needs of sustainable development. Herein, an electroless plating method was employed to autogenous growth of ultrathin Ni–Fe2B nanosheet arrays on nickel foam (NF), in which the whole liquid phase reduction reaction took no more than 20 min and did not require any other treatments such as calcination. In 1.0 M KOH electrolyte, the resulted Ni–Fe2B ultrathin nanosheet displayed a low overpotential of 250 mV for OER and 115 mV for HER to deliver a current density of 10 mA cm−2, and both OER and HER activities remained stable after 26 h stability testing. Further, the couple electrodes composed of Ni–Fe2B could afford a current density of 10 mA cm−2 towards overall water splitting at a cell voltage of 1.64 V in 1.0 M KOH and along with excellent stability for 26 h. The outstanding electrocatalytic activities can be attributed to the synergistic effect of electron-coupling across Ni and Fe atoms and active sites exposed by large surface area. The effective combination of low cost and high electrocatalytic activity brings about a promising prospect for Ni–Fe2B nanosheet arrays in the field of overall water splitting.