Synergistic interface and oxygen/nitrogen vacancy engineering in g-C3N4/Cu2O under high pressure for efficient CO2 photoreduction.

This study explores highly active nitride-based g-C3N4/Cu2O photocatalysts for CO2 photoconversion by synthesizing them through high-pressure torsion (HPT) straining. Data indicate that increasing the applied strain under high pressure promotes vacancy formation and improves the electronic interaction at the g-C3N4/Cu2O interphases, enabling superior charge separation and extended light absorption. The generation of dual vacancies of oxygen and nitrogen is verified by electron paramagnetic resonance and Fourier transform infrared spectroscopic methods, and the generation of a type-II heterojunction is confirmed by band structure analysis. Photocatalytic experiments reveal a threefold increase in the formation of CO and CH4 using g-C3N4/Cu2O in comparison with the pure g-C3N4 photocatalyst. This investigation highlights the potential of synergic vacancy and interface engineering, realized by HPT for the first time in nitride-based composites, for sustainable CO2 photoreduction applications.