Protonated g-C3N4/oxygen-doped g-C3N4 S-scheme homojunction fabricated by electrostatic self-assembly for photocatalytic hydrogen evolution and tetracycline hydrochloride degradation

Abstract

S-scheme photocatalytic systems with high redox ability and separation efficiency of photoexcited charge carriers supply considerable prospects for environmental optimization and sustainable energy development. However, coupling well-suited reduction and oxidation components for target reactions remains a challenge worth exploring. Herein, an efficient S-scheme system for H2 generation and tetracycline hydrochloride (TCH) photodegradation based on protonated g-C3N4 (PCN) coupling with oxygen-doped g-C3N4 (OCN) is fabricated via a facile electrostatic self-assembly strategy. Intimate interfacial interactions originating from the ultrathin nanostructure and staggered energy band arrangement for the S-scheme charge transfer pathway provide compelling advantages for the highly efficient separation of photoinduced electron-hole pairs in the as-designed PCN/OCN homojunction. The in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) techniques and electron paramagnetic resonance (EPR) measurements are applied to confirm the successful construction and the validity of the S-scheme charge transfer pathway. The obtained PCN/OCN composites with optimal ratio achieve a decent H2 generation rate of 6184.7 μmol g−1 h−1 outpacing the single PCN by approximately 4.8-fold, and 90.5 % TCH photodegradation efficiency is also realized within 90 min. This work provides a delicate fresh round of elevation for the exploration of an effective photocatalytic system.