Amorphous–Crystalline Interface Coupling of IrNiOx/WO3 for Efficient and Stable Acidic Water Splitting

Developing an efficient and stable bifunctional electrocatalyst for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in acidic media is of great significance, yet remains challenging. Herein, a bifunctional electrocatalyst supported by carbon cloth, denoted as IrNiOx/WO3, was designed and synthesized through heterostructured coupling of active amorphous IrNiOx with stable crystalline WO3. Benefiting from the pronounced electron interaction stemming from the as-generated numerous heterointerfaces, as-fabricated IrNiOx/WO3 demonstrates a low cell voltage of 1.539 V to achieve 10 mA cm–2 for water splitting with a low Ir loading of 0.8 wt % while maintaining stability over 100 h of continuous electrolysis in 0.5 M H2SO4. Furthermore, through comprehensive structural characterization and theoretical analysis, it was revealed that the Ir sites in the Ir–O–Ni configuration within amorphous IrNiOx serve as the primary active sites for both HER and OER processes. Moreover, the corresponding energy barriers were found to be significantly lowered due to the strong electronic interaction between amorphous IrNiOx and crystalline WO3. This study provides a strategy for designing amorphous–crystalline heterostructured electrocatalysts with ideal interfacial properties for efficient overall water splitting.