Hydrothermal combined with electrodeposition construction of a stable Co9S8/Ni3S2@NiFe-LDH heterostructure electrocatalyst for overall water splitting

Abstract

Electrochemical water splitting provides a prominent route towards clean energy conversion and storage, while unsuitable catalysts restrict its application. Core–shell hierarchical heterostructure materials with strong synergistic effects based on non-noble metal elements have been developed to compensate for inadequacy. In this work, a core–shell hierarchical heterostructure Co₉S₈/Ni₃S₂@NiFe-LDH electrocatalyst was prepared via hydrothermal and electrodeposition methods. The resultant Co₉S₈/Ni₃S₂@NiFe-120 electrocatalyst consists of Co₉S₈ substrates as the core and NiFe-LDHs as the shell, and exhibits excellent overall water splitting electrocatalytic activity with a low overpotential of 229 mV for the oxygen evolution reaction (OER), and 151 mV for the hydrogen evolution reaction (HER) and a full cell voltage of 1.62 V at 10 mA cm⁻² current density. The core–shell heterostructure constructed by electrodeposition endows the catalyst with outstanding stability and low degradation in long-term catalytic processes as shown by continuous chronopotentiometry tests at current densities of 50, 100 and 200 mA cm⁻² for 72 h. The as-prepared core–shell hierarchically heterostructural Co₉S₈/Ni₃S₂@NiFe-120 with high-efficiency and good-durability is a promising bifunctional electrocatalyst towards practical applications in overall water splitting.