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

Abstract

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.