Hierarchically porous FeNi3@FeNi layered double hydroxide nanostructures: one-step fast electrodeposition and highly efficient electrocatalytic performances for overall water splitting

Abstract

FeNi-layered double hydroxide (LDH) is thought to be an excellent electrocatalyst for oxygen evolution reaction (OER) but it always shows extremely poor electrocatalytic activity toward hydrogen evolution reaction (HER) in alkaline media. Hence, it is significant to improve its HER activity to make it a bifunctional electrocatalyst for the decomposition of water. Here, a simple galvanostatic electrodeposition method was designed for the successful construction of the bifunctional FeNi₃@FeNi LDH electrocatalyst. The as-prepared catalyst displayed excellent electrocatalytic activity for HER/OER in 1.0 M KOH. To drive the current density of 10 mA cm⁻² for HER/OER, an overpotential of 106/199 mV was needed, respectively. In a two-electrode system with the FeNi₃@FeNi LDH/NF as the anode and the cathode simultaneously, the overpotential hardly changed after continuously working for 168 h at 10 mA cm⁻². Compared with other FeNi-based catalysts, the present catalyst possessed close or better electrocatalytic activity.