Construction of WS2/MoSe2 heterojunction for efficient photoelectrocatalytic hydrogen evolution

As a typical n-type semiconductor, MoSe 2 is limited in the application of photoelectrocatalytic hydrogen evolution due to the rapid recombination of photo-generated electron-hole pairs. To solve this problem, in this work, a p-type WS 2 is selected to design a WS 2 /MoSe 2 hybrid semiconductor catalyst with a p-n heterojunction . The obtained samples were characterized by XRD , Raman, SEM, TEM, UV and XPS . Besides, the photoelectrocatalytic performances for hydrogen production were also evaluated. It was found that the WS 2 /MoSe 2 hybrid catalyst with a loading of 20% WS 2 (20W-M) showed the best photocatalytic performance with a photocurrent density of 35 μA cm -2 at -0.6 V (vs SCE), much larger than those of single MoSe 2 (20 μA cm -2 ) and WS 2 (3.5 μA cm -2 ). And the improved performances should be ascribed to the construction of p-n heterojunction , which leads to the change of photoelectron-hole transport mode, accelerates the separation speed of carriers and prolongs the carrier lifetime. This work demonstrates the promoting effect of WS 2 as a cocatalyst and this strategy can be extended to other semiconductors.