Enhanced electrocatalytic overall water splitting over novel one-pot synthesized Ru–MoO3-x and Fe3O4–NiFe layered double hydroxide on Ni foam

Abstract

Herein, two novel electrocatalysts are simultaneously grown on Ni foam (NF) through a one-step hydrothermal method. The as-prepared Ru–MoO3-x NF exhibits good performance for HER with low overpotentials of 12 mV at 10 mA cm−2 and 49 mV at 100 mA cm−2, a low Tafel slope of 32.96 mV dec−1, as well as an excellent durability at least lasting 17 h in alkaline media. The Fe3O4–NiFe LDH NF (layered double hydroxide nickel foam) ultrathin nanosheets electrode shows a low OER overpotential of 216 mV at 10 mA cm−2 and a small Tafel slope of 42.42 mV dec−1. Moreover, a two-electrode water splitting device is fabricated with Ru–MoO3-x NF as cathode and Fe3O4–NiFe LDH NF as anode, it only requires 1.46 V at 10 mA cm−2 and exhibits a long term durability without obvious loss of activity after continuously operating for 180 h. The superior catalytic behavior should be originated from the open heterostructure and oxygen vacancies with high intrinsic activity, abundant exposed active sites, and fast charge transfer. This work provides a new strategy to design heterostructure and transition metal oxides catalysts with improved catalytic activity and durability by a facile route for overall water splitting or other applications.