The Spatially Oriented Charge Flow and Photocatalysis Mechanism on Internal van der Waals Heterostructures Enhanced g-C3N4

Undirected charge transfer and inhibited interlayer electron migration largely limit the photocatalytic efficiency of two-dimensional (2D) layered graphitic carbon nitride (g-C3N4). Herein, we present a facile chemical approach to forming internal van der Waals heterostructures (IVDWHs) within g-C3N4, which enhance the interlayer coulomb interaction and facilitate the spatially oriented charge separation. Such a structure, generated through simultaneous g-C3N4 intralayer modification by O and interlayer intercalation by K, enables the oriented charge flow between the layers, enhancing the accumulation of the localized electrons and promoting the production of active radicals for the activation of reactants as suggested by density functional theory calculations. The resultant O, K-functionalized g-C3N4 with IVDWHs shows an enhanced photocatalytic activity, with nearly 100% enhancement of NO purification efficiency compared with pristine g-C3N4. The reaction mechanism for NO purification is also provided, in which the functionality of IVDWHs could effectively restrain the production of toxic intermediates and promote the selectivity for final products. This work provides a strategy to engineer heterostructures within 2D materials for tunable charge carrier separations and migrations for advanced energy and environmental catalysis.