Bi2WO6/COF S-scheme heterostructure photocatalyst for H2O2 production†

Abstract

Artificial photosynthesis offers a viable strategy for sustainable and environmentally friendly H₂O₂ production. However, conventional inorganic semiconductor photocatalysts often face limitations such as restricted light absorption, inadequate redox ability, small specific surface area and poor stability, which greatly restrict their practical applications. Herein, an innovative inorganic/organic S-scheme heterojunction is fabricated by an electrostatic self-assembling method. The optimized BT-12 composite demonstrates a significantly enhanced photocatalytic H₂O₂ production rate of 723 μmol L⁻¹, surpassing the rates achieved by pure Bi₂WO₆ and TpPa-Cl-COF by factors of 10 and 2.9, respectively. This improvement can be attributed to the synergistic effects of enhanced light absorption, increased specific surface area, and effective separation of charge carriers and redox active sites, as well as the strong redox ability induced by the S-scheme heterojunction. Density functional theory (DFT) calculations along with X-ray photoelectron spectroscopy (XPS) measurements and electron paramagnetic resonance (EPR) characterization confirm the step-by-step charge transfer pathway. The active species trapping experiments validate that H₂O₂ is predominantly produced by a two-step one-electron process. This work highlights an innovative and promising strategy for constructing a highly efficient photocatalytic system based on inorganic/organic heterojunctions.