Superhydrophilic NiFe-LDH@Co9S8-Ni3S2/NF heterostructures for high-current-density freshwater/seawater oxidation electrocatalysts

Abstract

Designing oxygen evolution reaction (OER) electrocatalysts with high efficiency and stability at large current densities is paramount for achieving hydrogen production through water splitting. In this study, a heterostructured NiFe-LDH coating Co9S8-Ni3S2 grown on nickel foam (NiFe-LDH@Co9S8-Ni3S2/NF) was successfully synthesized. The distinctive hierarchical structures featuring abundant heterointerfaces can effectively expose abundant active sites. The synergistic effect and strong electronic interaction between Co9S8-Ni3S2 and NiFe-LDH can enhance the intrinsic OER activity. Furthermore, the superhydrophilic characteristic of NiFe-LDH@Co9S8-Ni3S2/NF favors close contact between the electrode and electrolyte. Due to these advantages, NiFe-LDH@Co9S8-Ni3S2/NF can provide distinguished OER activity with low overpotentials of 274 mV in alkaline freshwater and 298 mV in alkaline seawater at 1000 mA cm−2, along with outstanding stability at high current density of 500 mA cm−2 over 200 h in both solutions. This study offers a valuable insight into fabricating high-performance OER electrocatalysts for seawater electrolysis in industrial applications.