Electronic modulation via oxygen doping in Cu-porphyrin/g-C3N4 heterojunctions for enhanced sonophotocatalytic H2 production

The development of efficient and stable photocatalysts for hydrogen evolution is crucial for solar-to-fuel conversion. Here, we report Cu-porphyrin (CuTCPP)/oxygen-doped g-C 3 N 4 (O–CN) nanohybrids as high-performance sonophotocatalysts, where strong π–π stacking interactions create robust heterojunctions that promote efficient charge separation and transfer. The optimal 2 % CuTCPP/O–CN2 sample exhibited a 3.3-fold enhancement in H 2 evolution compared to O–CN2 under simulated light coupled with ultrasonication. Experimental results combined with density functional theory (DFT) calculations confirmed the suppression of charge recombination and highlighted the synergistic contribution of ultrasonic excitation with light irradiation. Furthermore, oxygen doping was found to not only reinforce the CuTCPP/O–CN interface but also provides robust anchoring sites for Pt cocatalysts, preventing leaching and aggregation while electronically modulating Pt to optimize its d-band center and H 2 adsorption free energy. These findings provide valuable insights into the rational design of stable and high-active hybrid photocatalysts for solar fuel generation.