Defective Tungsten Oxides with Stacking Faults for Proton Exchange Membrane Green‐Hydrogen Generation

Defects can introduce atomic structural modulation and tailor performance of materials. Herein, it demonstrates that semiconductor WO3 with inert electrocatalytic behavior can be activated through defect‐induced tensile strains. Structural characterizations reveal that when simply treated in Ar/H2 atmosphere, oxygen vacancies will generate in WO3 and cause defective structures. Stacking faults are found in defects, thus modulating electronic structure and transforming electrocatalytic‐inert WO3 into highly active electrocatalysts. Density functional theory (DFT) calculations are performed to calculate *H adsorption energies on various WOx surfaces, revealing the oxygen vacancy composition and strain predicted to optimize the catalytic activity of hydrogen evolution reaction (HER). Such defective tungsten oxides can be integrated into commercial proton exchange membrane (PEM) electrolyser with comparable performance toward Pt‐based PEM. This work demonstrates defective metal oxides as promising non‐noble metal catalysts for commercial PEM green‐hydrogen generation. By means of geometric phase analysis, the strain behavior of oxygen vacancies and their induced stacking faults have been analyzed in defective tungsten oxides. ɛxx strain map indicates that the sample has a significant strain trend, and the stacking fault induced by oxygen vacancy optimizes the electronic structure of WO2.9 and exhibits better hydrogen evolution activity.