Tuning Catalytic Performance of C2N/GaN Heterostructure for Hydrogen Evolution Reaction by Doping

Abstract In this work, a systematic theoretical study of the hydrogen evolution reaction (HER) catalytic activity of C 2 N/GaN heterostructure is carried out based on first principles. An indirect bandgap of 1.99 eV and type‐II band alignment are formed in the C 2 N/GaN heterostructure, which can facilitate the spatially efficient separation of photogenerated carrier pairs, and the band edge position matches the reduction potential of water. The catalytic performance of the HER reaction at the C and N sites is compared and that the N site is better in performance is found, but still requires a potential barrier of 0.60 eV. In order to improve the catalytic performance of the C 2 N/GaN heterostructure, an N atom is replaced by a P atom to obtain P‐C 2 N/GaN. The band alignment of the P‐C 2 N/GaN heterostructure is still type‐II, and the band edges satisfy the reduction potential of water. Fortunately, the P or N sites play a crucial role in the HER process with a relatively low overpotential of 0.38 eV, which suggests that P‐C 2 N/GaN can improve the catalytic performance of the heterojunction. Overall, the P‐C 2 N/GaN heterostructure has suitable band gap values and band edges, and efficient charge separation in the heterostructure makes it a promising HER catalyst.