Tunable type-I/type-II transition in g-C₃N₄/graphyne heterostructure by BN-doping: A promising photocatalyst

As a promising photocatalytic material, g-C₃N₄ has drawn tremendous research interest. However, the fast charge recombination and narrow range of solar absorption restrain its practical application. Herein, for the first time, based on extensive hybrid functional calculations, graphyne (Gyne), a new two dimensional material, is used to form a layered vdW-nanohybrid with g-C₃N₄ to enhance the photoelectrocatalytic activity of g-C₃N₄. A comprehensive theoretical study of interfacial properties of g-C₃N₄/Gyne heterostructure including the band structure, partial density of state, optical absorption, wave functions, charge density difference, band alignment and photocurrent density is acquired to provide deep insight into the photocatalytic performance. The calculated results show that g-C₃N₄/Gyne heterostructure exhibits tremendous photocatalytic performance as that of recently experimentally synthesized Gyne family based nanocomposite, g-C₃N₄/graphdiyne (g-C₃N₄/GDyne). The designed g-C₃N₄/Gyne heterostructure has a fourfold increase in photocurrent density (0.937 μA/mm²) compared with that of g-C₃N₄ (0.233 μA/mm²). More importantly, the photocatalytic performance of g-C₃N₄/Gyne can be further improved by doping 2BN-pairs into Gyne layer. Theoretical prediction indicates that g-C₃N₄/2BN-Gyne even realizes a sevenfold increase in photocurrent density (1.669 μA/mm²) due to the type II band alignment, broadened light absorption range and much smaller effective mass, providing helpful physical mechanism information for further optimizing the optoelectronic properties of g-C₃N₄/GDyne and g-C₃N₄/Gyne. Our theoretical work provides stepping stone into the design of highly efficient g–C₃N₄–based photocatalysts and a fully coherent picture about the interfaces of g-C₃N₄/GDyne and g-C₃N₄/Gyne heterostructures can also be obtained.