Bridging localized electron states of pyrite-type CoS2 cocatalyst for activated solar H2 evolution

The development of low-cost and high-active cocatalysts is one of the most significant links for photocatalytic water splitting. Herein, a novel strategy of electron delocalization modulation for transition metal sulfides has been developed by anion hybridization. P-modified CoS2 (CoS2∣P) nanocrystals were firstly fabricated via a gas-solid reaction and coupled with CdS nanorods to construct a composite catalyst for solar H2 evolution reaction (HER). The CdS/CoS2∣P catalyst shows an HER rate of 57.8 µmol·h−1, which is 18 times that of the bare CdS, 8 times that of the CdS/CoS2, and twice that of Pt/CdS. The reduced energy barrier and suppressed reverse reaction for HER on the catalyst have been predicted and explained by density functional theory (DFT) calculation. The underlying design strategy of novel cocatalysts by electron delocalization modulation may shed light on the rational development of other advanced catalysts for energy conversion.