Insights into atomic level defect commanding coupling with n–π* excitation in carbon nitride for enhanced photocatalytic hydrogen production and CO2 reduction†

Abstract

The restricted internal charge migration and inadequate light trapping impede the optimization of the intrinsic efficacy of the g-C₃N₄ photocatalyst. In the present study, efforts were directed towards minimizing the impact of in-plane defects resulting from the N–(C)₃ defect site, with the objective of enhancing the efficient rapid separation of charge carriers. Moreover, the incorporation of a C–C bond within the tris-triazine units facilitated n → π* excitation, thereby enhancing the efficiency of light utilization. Consequently, the modified catalyst exhibited markedly enhanced photocatalytic activity under visible light, with an absorption edge extending from 450 to 550 nm. The optimized SCN-5 sample demonstrated notable enhancements in reaction rates for hydrogen production, CO₂ reduction, and pollutant degradation, with factors of 11.0, 4.2, and 14.3, respectively. These improvements can be attributed to the enhanced light trapping and charge separation capabilities of the sample. This research underscores the significance of impeding in-plane defects and fostering local n → π* excitation in order to augment intrinsic visible light catalytic reactions. This provides a vital mechanism for the development of high-performance photocatalysts.