Interface electronic coupling in NiCo2S4 nanorod-amorphous FeOOH nanosheets with enhanced catalytic activity in the oxygen evolution reaction†

Abstract

The oxygen evolution reaction (OER) involves a four-electron couple transfer step with slow reaction kinetics, which is considered a bottleneck in the water-splitting process. Therefore, exploiting earth-abundant and cost-effective OER electrocatalysts has become promising in large-scale industrial applications. Herein, a heterogeneous interface OER catalyst consisting of NiCo₂S₄@FeOOH-1 supported on foam nickel (NF) was synthesized through a two-step hydrothermal-chemical etching method. NiCo₂S₄@FeOOH-1 showed an excellent performance as an OER catalyst, requiring an overpotential of only 385.6 mV to reach 100 mA cm⁻² and it exhibited a Tafel slope of 80.4 mV dec⁻¹, indicating the rapid reaction kinetics. The NiCo₂S₄@FeOOH-1 catalyst also exhibited exceptional long-term stability, maintaining a consistent performance for more than 20 hours in an alkaline environment. The robust interfacial effect between NiCo₂S₄ and FeOOH effectively shortened the electron transport pathway, contributing to the enhancement in electrocatalytic performance. This study provides significant insights into the catalytic mechanisms and opens a pathway for the development of hierarchical structures aimed at creating highly efficient and durable OER electrocatalysts.