Novel MoSSe/Bi2WO6 S-scheme heterojunction photocatalysts for significantly improved photoelectrochemical and photocatalytic performance

Abstract

Two-dimensional MoSSe nanoplates demonstrate low internal resistance and outstanding reduction potential, while Bi2WO6 nanoparticles exhibit zero-dimensional appearance and high oxidation potential. Herein, novel MoSSe/Bi2WO6 step-scheme (S-scheme) heterojunction photocatalysts (MSSB) were prepared to combine the properties of those two materials. These catalysts were confirmed to have lower internal resistance (as low as 0.07 kΩ), and higher carriers’ separation efficiency due to the well-contacted two-dimensional/zero-dimensional structure. More importantly, the heterojunction catalysts displayed both good oxidation and reduction performance which have been confirmed by the conducted catalytic tests. With an optimized Bi2WO6 loading ratio, degradation rates (k) and photocurrent density of the MSSB2 sample were 2.09, and 8.31 times more than that of MoSSe, as well as 1.77, and 26.27 times more than that of Bi2WO6. Active species (superoxide radical •O2− and hydroxyl radical •OH) were detected by the electron spin resonance tool which could infer that a S-scheme heterojunction has already constructed between the Bi2WO6 and MoSSe. Driven by the MoSSe and band edge bending, the e– on the conduction band of Bi2WO6 readily slid toward MoSSe and recombines with the h+ on the valence band of MoSSe, while retaining the powerful e– and h+ with high redox potential on the CB of MoSSe and VB of Bi2WO6. This work further provided a novel strategy for developing S-scheme nano-heterojunction catalysts and revealed their prospects in photoelectrochemistry and photocatalysis.