Efficient H2O2 production coupling Rhodamine B degradation over covalent organic framework/g-C3N4 with S-scheme charge separation mechanism and fully hole-electron utilization ability

Abstract

Cooperative coupling of photocatalytic hydrogen peroxide production with organic pollutants degradation has an expansive perspective in energy storage and environmental conservation. Herein, an S-scheme heterojunction is constructed by hybridizing a 3D flower like Schiff-based covalent organic framework (COF) with a porous structure g-C₃N₄, and a comprehensive strategy is proposed to achieve efficient H₂O₂ production yield coupling highly Rhodamine B (RhB) degradation rate. The charge carrier transfer mechanism is validated by an in-situ X-ray photoelectron spectroscopy, the density functional theory calculation, and a femtosecond transient absorption spectroscopy. Interestingly, the COF/g-C₃N₄ S-scheme heterojunction exhibits better charge separation efficiency compared to bare COF and pure g-C₃N₄, resulting in ameliorative photocatalytic activity. In addition, RhB is employed to consume photogenerated holes. Remarkably, 2307 μmol g⁻¹ h⁻¹ H₂O₂ achieved over 10%-COF/g-C₃N₄ composite in RhB solution and O₂ atmosphere, and 100%-RhB degradation rate obtained at 45 min. This work improves a facile strategy to ameliorate Schiff COF-based S-scheme heterojunction for efficient H₂O₂ production with full hole-electron utilization ability.