Interfacial Engineering of Hierarchical Iron Oxysulfide Integrated MoS ₂ Heterostructures for Enhanced Oxygen Evolution Electrocatalysis

Abstract Interfacial engineering plays a key role in enhancing the performance of electrocatalysts for the oxygen evolution reaction (OER). In this study, we report the development of a hierarchical heterostructure composed of iron oxysulfides integrated with MoS₂ on nickel foam (Fe‐SO@MoS 2 /NF) to serve as an advanced OER electrocatalyst. The vertically aligned morphology by growing layered MoS₂ on iron oxysulfides can facilitate efficient mass transport, accelerate reaction kinetic and improve ion diffusion at the catalyst‐electrolyte interface. Surface modification at the interface is favorable to improving the conductivity and boosting the catalytic activity. Electrochemical measurements reveal that the optimized heterostructure demonstrates superior OER performance, with a low overpotential of 253 mV at 10 mA cm −2 and Tafel slope of 62.1 mV dec −1 . The enhanced catalytic activity can be attributed to the well‐engineered interface between iron oxysulfides and MoS₂, which promotes rapid electron transfer and stabilizes the catalyst under operational conditions. Furthermore, the long term stability of the catalyst under alkaline conditions highlights its potential for industrial water‐splitting applications. This work gives a comprehensive understanding of the role of interfacial engineering in hierarchical heterostructures and opens new avenues for designing efficient transition metal oxysulfides‐based OER electrocatalysts.