Graphene-Modulated PDI/g-C3N4 All-Organic S-Scheme Heterojunction Photocatalysts for Efficient CO2 Reduction under Full-Spectrum Irradiation

Inspired by natural photosynthesis, exploring high-efficiency S-scheme heterojunction photocatalysts, especially with all-organic ones, for CO2 reduction is of great significance to tackle energy and environment issues. Herein, the dimension-matched perylene diimide/graphene-g-C3N4 (PDI/G-CN) S-scheme nanosheet heterojunctions have been successfully constructed as an efficient full-spectrum responsive photocatalyst for converting CO2 into CO and CH4 with 16-time improvement compared with pristine CN nanosheets. On the basis of the steady and transient photoluminescence spectra, electron paramagnetic resonance signals, and kelvin probe measurement analyses, and so on, it is confirmed that the exceptional photoactivity is mainly ascribed to the interfacial modulation with G, by which the efficient S-scheme charge transfer and separation is strengthened and the optimized amount of highly dispersed PDI is increased via the pi-pi interactions. This work elucidates the potential practicability on all-organic CN-based S-scheme heterojunction photocatalysts for efficient solar-to-energy conversion by CO2 reduction.