Multiple hydrogen bonds and internal electric field modulated directional charge transfer channels for photocatalytic water splitting

Control of intermolecular interactions is crucial for regulating self-assembly processes in nature. Herein, using hydrogen bonds as stabilizers, we demonstrate an innovative approach for assembling highly reactive 2D Ta3N5 nanomeshes embedded with nitrogen self-doped carbon quantum dots (NCQDs). These Schiff base-derived NCQDs exhibit good hydrophilicity and act as both photosensitizers and electron reservoirs in the hybrid system.​ Strong bonding interactions exist between the H atoms of -OH/-NH groups on the NCQD surface and the N atoms of 2D Ta3N5 nanomeshes (i.e., O–H···N and N–H···N hydrogen bonds). These interactions direct the formation of an extended 3D hydrogen-bonded coupling framework. Within the NCQDs/Ta3N5 nanomeshes, the internal electric field and interfacial hydrogen bonds provide directional charge-transfer channels, which facilitate the separation and directional migration of photocarriers. Further density functional theory (DFT) calculations reveal that the formed O–H···N and N–H···N bonds significantly reduce the Gibbs free energy barrier of the rate-limiting reaction and the reaction barrier for H2O dissociation, thereby enhancing the material’s photooxidation and photoreduction activities. Our results establish a close relationship between intermolecular hyperconjugation theory and the photocatalytic mechanism.