Crystallinity Modulation of Electron Acceptor in One-Photon Excitation Pathway-Based Heterostructure for Visible-Light Photocatalysis

Graphitic carbon nitride is viewed as promising visible-light photocatalyst. However, the high recombination rate of photogenerated carriers within the bulk strongly limits its performance and achieving highly efficient heterostructure remains challenging. Herein, construction of carbon nitride-related heterostructures based on the one-photon excitation pathway (OPEP) mechanism is reported and the complex interplay between component crystallinity and charge transfer kinetics is unraveled. As a proof of concept, prototype TiO₂ is selected as the electron-acceptor while crystalline carbon nitride (CCN) is used as the light-absorber. Interestingly, a counter-intuitive phenomenon is found that decreased crystallinity of the electron acceptor is favorable for charge carrier transfer through the heterostructure interface. Detailed structural analysis demonstrates TiO₂ with low crystallinity can introduce more dramatic changes to electron distribution of C₃N₄ than those from highly crystalline counterparts when forming heterostructures, leading to the highly efficient interface. Based on the aforementioned observation, the designed heterostructure (CCN/low-crystalline TiO₂) presents a 6 and 4.8 times optimized photocatalytic hydrogen production rate of CCN and CCN/high-crystalline TiO₂, respectively. This finding challenges the conventional view and may advance the in-depth understanding for construction of OPEP-related heterostructures and design of highly efficient composite photocatalysts via structure modulation.