Constructing Carbon Nitride Donor-Acceptor Structures by Vacancy Engineering and Sulfone-Containing Molecule Grafting...

Carbon nitride (CN) has attracted extensive attention in the field of photocatalytic CO₂ reduction owing to its controllable structure and low preparation cost. However, it suffers from severe recombination of photogenerated carriers and strong localization of the π-conjugated system, leading to unsatisfactory photocatalytic performance. Although defect engineering can enhance charge separation by breaking the periodic structure of CN, the π-electron delocalization remains confined. Meanwhile, constructing donor-acceptor (D-A) structures with conjugated π-systems can extend electron delocalization and promote charge transfer. Herein, by introducing carbon vacancies and grafting sulfone-containing electron-withdrawing molecules, we prepare photocatalysts with intramolecular D-A structure (V_C-DSDA), where the sulfone unit bridges electron-rich triazine rings to facilitate directional charge transfer. Density functional theory (DFT) calculations show that the synergistic effect of vacancy engineering with the D-A structure breaks the periodic structure of CN and extends the π-electron off-domain range, which significantly improves the separation efficiency of the photogenerated charges. As a result, the optimized 5% V_C-DSDA achieves a remarkable CO generation rate of 35.57 μmol g^-1 h^-1, which was 6.4 and 2.6 times higher than that of pristine and vacancy-modified CN. This article demonstrates a dual-regulation strategy for designing high-performance CN photocatalysts through defect engineering and molecular grafting.