Construction of p–n Heterojunctions by Co9S8 Modified Rare-Earth Metal Sm-Tungstates for Photocatalytic Hydrogen Evolution

The p–n type Sm 2 WO 6 -Co 9 S 8 heterojunction with two-dimensional coupling interface was successfully synthesized by electrostatic self-assembly. The unique rhombic morphology of Sm 2 WO 6 and Co 9 S 8 nanoparticles also effectively improve the light utilization efficiency. The intervention of Co 9 S 8 enhances the visible light absorption capacity of m 2 WO 6 /Co 9 S 8 . The Sm 2 WO 6 /Co 9 S 8 greatly increases the specific surface area and provides a rich reaction site. Recombination of photogenerated carriers in Sm 2 WO 6 /Co 9 S 8 heterojunctions is effectively inhibited. The p–n type Sm 2 WO 6 -Co 9 S 8 heterojunction results show that the optimized Sm 2 WO 6 /Co 9 S 8 heterojunction exhibits significant hydrogen evolution activity, and the optimal Sm 2 WO 6 /Co 9 S 8 -25 composite has 117.5 μmol hydrogen evolution activity, it’s close to four times Co 9 S 8 , close to 143 times Sm 2 WO 6 . The stability of the composite Sm 2 WO 6 /Co 9 S 8 is the better. Under the built-in electric field induced by p–n heterojunction, using of p–n heterojunction interactions and electron transport modes, the Sm 2 WO 6 /Co 9 S 8 can effectively achieve the remarkable effect of its internal carrier separation. This work also provides new opportunities for studying rare earth element tungstate photocatalysts. Graphical Abstract