Visible light-driven H2O2 synthesis by a Cu3BiS3 photocathode via a photoelectrochemical indirect two-electron oxygen reduction reaction

In this study, a flat and uniform polycrystalline Cu3BiS3 (CBS) thin film was prepared on a molybdenum-coated glass (Mo-SLG) by spray pyrolysis deposition for generation of hydrogen peroxide (H2O2). The dense structure of the film promoted charge transmission, and the combination of the p-type CBS and n-type semiconductor In2S3 deposited by the chemical bath method improved the electron-hole separation efficiency, resulting in a significantly enhanced photocurrent. Deposition of Au nanoparticles reduced the required free energy for oxygen reduction reaction (ORR), improving the selectivity from O-2 to H2O2. The photoelectrochemical (PEC) synthesis proceeds by an indirect 2e(-) ORR initial formation of superoxide, which is disproportionated to H2O2. In the presence of oxygen and visible light, Au-In2S3/CBS could be used to synthesize H2O2 (5.5 mg.L-1.h(-1).cm(-1)) with good Faraday efficiency (71%). This study provided a practical strategy for designing a highly efficient photocathode to produce H2O2 based on improvement in electron-hole transmission efficiency and product selectivity.