Preparation of 2D/2D g-C₃N₃/g-C₃N₄ heterojunctons for enhanced photocatalytic hydrogen production

Heterostructure construction is a powerful method for building a highly efficient photocatalyst of hydrogen production by water splitting. In this study, 2D/2D g-C 3 N 3 /g-C 3 N 4 heterojunctions were fabricated by loading 2D g-C 3 N 3 on 2D g-C 3 N 4 using a hydrothermal method. The synthesized composites were characterized by various techniques. The photocatalytic H 2 production activities under simulated sunlight irradiation were investigated. The results show that g-C 3 N 3 and g-C 3 N 4 formed a 2D/2D heterojunction, which modified the specific surface area and band gap, supplied richer active sites for H 2 production, promoted the effective separation and migration efficiency of photogenerated carriers, and then significantly enhanced the photocatalytic performance. Under simulated sunlight, the average H 2 evolution rate of the synthesized 2D/2D g-C 3 N 3 /g-C 3 N 4 composite reached 3.26 mmol ⋅ h[Formula: see text] ⋅ g[Formula: see text] with the best apparent quantum efficiency of 14.28% and excellent stability of recycling. The average H 2 evolution rate of the composite is 9.9 times that of 2D g-C 3 N 3 and 5.3 times that of 2D g-C 3 N 4 . By analyzing the energy band gap during the heterojunction formation process, the mechanism of the enhanced photocatalytic hydrogen evolution was discussed. This work may afford the potential applications of 2D/2D graphitic carbon nitrides composites.