Construction of WS2/MoSe2 heterojunction for efficient photoelectrocatalytic hydrogen evolution

As a typical n-type semiconductor, MoSe2 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 WS2 is selected to design a WS2/MoSe2 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 WS2/MoSe2 hybrid catalyst with a loading of 20% WS2 (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 MoSe2 (20 μA cm-2) and WS2 (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 WS2 as a cocatalyst and this strategy can be extended to other semiconductors.