Fine-tuning electronic structure of S-NiMoO4 coupled with NiFe-layered double hydroxides for enhanced electrochemical water oxidation

Abstract

The environmentally friendly and sustainable characteristics of hydrogen generation through water electrolysis have drawn considerable interest. However, the inherently retarded reaction dynamics of the oxygen evolution reaction (OER) limit its efficiency. Consequently, advancing high-performance and cost-effective OER electrocatalysts significantly strengthen the water electrolysis’ performance. A composite nanostructured catalyst is successfully developed by integrating S-doped NiMoO₄ with NiFe-layered double hydroxides (LDH). Characterization results indicate that the NiMoO₄-decorated NiFe-LDH increases catalytic efficiency by providing additional active sites, while the introduced S further enhances electrical conductivity. Electrochemical tests reveal that the OER capability of S-NiMoO₄@NiFe-LDH under alkaline conditions is exceptional, achieving a negligible overpotential of 256 mV at 50 mA cm⁻² and a minimal Tafel slope of 27.8 mV dec⁻¹, along with outstanding durability at 10 mA cm⁻² (200 h). Furthermore, electrochemical probe experiments and mechanistic analyses reveal the possible potential reaction route of the catalyst during the OER, playing a crucial role in clarifying how the adsorbate evolution mechanism (AEM) and the lattice oxygen mechanism (LOM) synergistically enhance catalytic performance. This study affords a compelling strategy for establishing stable and efficient catalysts for electrochemical water oxidation.