Construction of high-efficiency CoS@Nb₂O₅ heterojunctions accelerating charge transfer for boosting photocatalytic hydrogen evolution

The random movement and easy recombination of photoinduced charges lead to a low conversion efficiency for photocatalytic hydrogen evolution. The cocatalyst design is a promising route to address such problem through introducing an appropriate cocatalyst on the semiconductor photocatalysts to construct the high-efficiency heterojunctions. Herein, novel CoS/Nb₂O₅ heterojunctions were constructed via in-situ loading CoS cocatalyst on the surface of Nb₂O₅ nanosheets. Through the femtosecond-resolved transient absorption spectroscopy, the average lifetime of charge carriers for 10 wt% CoS/Nb₂O₅ (159.6 ps) is drastically shortened by contrast with that of Nb₂O₅ (5531.9 ps), strongly suggesting the rapid charge transfer from Nb₂O₅ to CoS. The significantly improved charge-transfer capacity contributes to a high photocatalytic hydrogen evolution rate of 355 µmol/h, up to 17.5 times compared with pristine Nb₂O₅. This work would provide a new design platform in the construction of photocatalytic heterojunctions with high charge-transfer efficiency.