Ultrafast charge-transfer at interfaces between 2D graphitic carbon nitride thin film and carbon fiber towards enhanced photocatalytic hydrogen evolution

Homogeneous deposition of graphitic carbon nitride (g-C₃N₄) onto substrates on a large scale is of great interest in recyclable photocatalysis. However, g-C₃N₄ films prepared via conventional thermal condensation are thick and have problem of bad interface contacts with substrate, resulting in a poor photocatalytic performance. Herein, a thermal vapor condensation approach is developed for the growth of homogeneous g-C₃N₄ thin film on large area carbon fiber cloths (CFC). CFC serves as the template to guide g-C₃N₄ growth, resulting in a conformal thin overlayer of g-C₃N₄ on CFC surface. Moreover, a robust interaction between g-C₃N₄ and carbon fibers is achieved. A close stacking of g-C₃N₄ interlayers coupled with an efficient electron-withdrawing ability of carbon fiber expedites charge transfer and suppresses charge recombination. Consequently, the film exhibits an enhanced photocatalytic H₂ evolution compared with g-C₃N₄ powder. A solid–gas bi-phase photocatalytic system is also constructed for manifesting remarkable superiority in gas evolution than solid–gas-liquid tri-phase system. Moreover, the sample is highly durable and recyclable, ensuring a robust, economical and environmentally friendly photocatalyst films.