Accompanying Bi clusters can effectively enhance the photocatalytic H2O2 production performance of Bi2Sn2O7/g-C3N4 S-Scheme heterostructures

Abstract

The construction of graphite-phase carbon nitride (g-C₃N₄) based heterojunction composites using the S-Scheme charge transfer mechanism is an effective strategy to enhance the photocatalytic production of H₂O₂. Herein, Bi₂Sn₂O₇/g-C₃N₄ heterojunction composites, featuring Bi clusters as charge transport mediators, were synthesized using self-assembly and in situ generation methods. Synchrotron radiation tests revealed the presence of Bi–Bi bonds, as well as Bi–N bonds, which not only facilitates the effective adsorption of reactive substances but also enhances charge transport at the interface. The successful construction of the S-Scheme charge transfer mechanism promotes the spatial separation of carriers in the conduction band, thereby inhibiting their recombination while maintaining a strong redox potential. This enhancement increases both the quantity and diversity of free radical species, ultimately boosting the generation of H₂O₂. Theoretical analyses indicate that the presence of Bi clusters reduces the adsorption energy of ∗OOH during the reaction. Notably, under visible light and simulated sunlight irradiation, the H₂O₂ generation rates of B–BSO/g-CN reached 191.1 μmol L⁻¹ h⁻¹ and 156.1 μmol L⁻¹ h⁻¹, which represent increases of 7.5 and 8.5 times, respectively, compared to pristine g-CN. This study underscores the significance of modulating the photocatalytic pathway through the targeted selection of metal clusters and reaction processes.