Optimizing Electronic Density at Active W Sites for Boosting Photocatalytic H2 Evolution

It is highly desirable but challenging to optimize the electronic structure of an active site to realize moderate active site-Hads bond energies for boosting photocatalytic H2 evolution. Herein, an interfacial engineering strategy is developed to simultaneously concentrate hydrogen species and accelerate the combination of an Hads intermediate to generate free H2 by constructing W–WC–W2C (WCC) cocatalysts. Systematic investigations reveal that hybridizing with W2C creates electron-rich W active sites and effectively induces the downshift of the d-band center of W in WC. Consequently, the strong W–Hads bonds on the surface of WC are weakened, thus promoting the desorption of Hads to rapidly produce free H2. The optimized 40-WCC/CdS photocatalyst exhibits a high hydrogen evolution rate of 63.6 mmol g–1 h–1 under visible light (≥420 nm) with an apparent quantum efficiency of 39.5% at 425 nm monochromatic light, which is about 40-fold of the pristine CdS. This work offers insights into the design of cocatalyst for high-efficiency photocatalytic H2 production.