Optimizing Electronic Density at Active W Sites for Boosting Photocatalytic H Evolution.

It is highly desirable but challenging to optimize the electronic structure of an active site to realize moderate active site-H bond energies for boosting photocatalytic H evolution. Herein, an interfacial engineering strategy is developed to simultaneously concentrate hydrogen species and accelerate the combination of an H intermediate to generate free H by constructing W-WC-WC (WCC) cocatalysts. Systematic investigations reveal that hybridizing with WC creates electron-rich W active sites and effectively induces the downshift of the d-band center of W in WC. Consequently, the strong W-H bonds on the surface of WC are weakened, thus promoting the desorption of H to rapidly produce free H. The optimized 40-WCC/CdS photocatalyst exhibits a high hydrogen evolution rate of 63.6 mmol g h 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 H production.