Improved photocatalytic hydrogen evolution on (Ru/WC)/CdS via modulating the transferring paths of photo-excited electrons

The proposed photo-excited electrons transferring paths and the photocatalytic H2 evolution mechanisms of (Ru/WC)/CdS (a) and Ru/(WC/CdS) ((b1), (b2) and (b3)). [Display omitted] •(Ru/WC)/CdS shows the most efficient photocatalytic activity.•Ru/(WC/CdS) is inferior to WC/CdS in activity.•Different electrons transferring path were demonstrated in (Ru/WC)CdS and Ru/(WC/CdS).•Ru and WC play different roles in photocatalysis. It is urgent to deep understanding the electron transfer mechanism in composite co-catalyst for efficient photocatalytic H2 evolution. Here, choosing Ru and WC as probes, (Ru/WC)/CdS and Ru/(WC/CdS) are designed. The Ru and WC show a synergistic effect in (Ru/WC)/CdS on photocatalytic H2 evolution. The optimum (Ru/WC)/CdS shows 16.8 mmol/h/g of H2 evolution, which are 1.93 and 1.34 times of that Ru / CdS and WC/CdS, respectively. Amazingly, the Ru / (WC/CdS) is inferior to WC/CdS, and the Ru shows harmful to WC in H2 evolution. The role of WC and Ru in photocatalysts and the electron transfer path of composite catalysts with different assembly methods are demonstrated. This study shows the relationship between activities and transferring paths of photoexited electrons.