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 O2 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.