Boosting Photocatalytic Activity over Graphitic Carbon Nitride by Hydrogen-Bonding-Assisted Charge Transfer

Graphiticcarbon nitride (g-C3N4) offersa great number of advantages for use as a photocatalyst to facilitatea wide variety of photocatalytic reactions. However, pristine g-C3N4 suffers from unsatisfactory photocatalytic performancein actual practice. Nonetheless, as a nitrogen-rich layered material,g-C3N4 offers abundant opportunities for theformation of hydrogen bonds between the NH/NH2 groups withinthe layers, which can incite proton transfer reactions owing to theinherent polarity of the proton donor and acceptor in the hydrogenbond and thereby improve the transport rate of photogenerated carriers,especially for holes. Yet, relatively little work has been done toimprove the photocatalytic performance of g-C3N4 through efforts to enhance its hydrogen bond network. The presentwork addresses this issue by constructing a hydrogen bond networkon g-C3N4 by pressurizing a mixture of pristineg-C3N4 nanosheets with water at a temperatureof 120 degrees C for 12 h. The results of nuclear magnetic resonancespectroscopy and density functional theory demonstrate that the hydrogenbonds on the g-C3N4 surfaces provide an additionalpathway for the separation of photogenerated electrons and enhancedhole transfer kinetics. The hydrogen bond network formed between theg-C3N4 layers effectively suppresses chargecomplexation, improves the photocatalytic efficiency of g-C3N4, and increases the selectivity for photocatalytic products.Our results provide valid insights for designing g-C3N4 photocatalysts with high photocatalytic activity.