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

The p–n type Sm2WO6-Co9S8 heterojunction with two-dimensional coupling interface was successfully synthesized by electrostatic self-assembly. The unique rhombic morphology of Sm2WO6 and Co9S8 nanoparticles also effectively improve the light utilization efficiency. The intervention of Co9S8 enhances the visible light absorption capacity of m2WO6/Co9S8. The Sm2WO6/Co9S8 greatly increases the specific surface area and provides a rich reaction site. Recombination of photogenerated carriers in Sm2WO6/Co9S8 heterojunctions is effectively inhibited. The p–n type Sm2WO6-Co9S8 heterojunction results show that the optimized Sm2WO6/Co9S8 heterojunction exhibits significant hydrogen evolution activity, and the optimal Sm2WO6/Co9S8-25 composite has 117.5 μmol hydrogen evolution activity, it's close to four times Co9S8, close to 143 times Sm2WO6. The stability of the composite Sm2WO6/Co9S8 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 Sm2WO6/Co9S8 can effectively achieve the remarkable effect of its internal carrier separation. This work also provides new opportunities for studying rare earth element tungstate photocatalysts. [ABSTRACT FROM AUTHOR]