Ozone modification as an efficient strategy for photocatalytic nitrogen fixation under visible light irradiation

Solar-driven reduction of dinitrogen to ammonia remains greatly challenging due to the stable triple bond between N atoms. In this study, g-C 3 N 4 photocatalysts were synthesized via ozone etching method. Due to the O 3 treatment, the resulting photocatalysts were rich in carbon vacancies. Etching g-C 3 N 4 with ozone for two hours (O 3 GCN-2), resulted in the decrease of size, and the structure becoming less compact. The specific surface area of O 3 GCN-2 increased up to ~ 12.751 m 2 ·g −1 , in comparison with that of the bulk g-C 3 N 4 (BGCN) that was only ~ 5.652 m 2 ·g −1 . The nitrogen fixation efficiency of O 3 GCN-2 was 2.72 times higher than that of BGCN under visible light irradiation. UV–vis, electrochemical impedance spectroscopy, and photocurrent measurements showed that O 3 GCN-2 had enhanced visible light absorption properties and enhanced electron–hole separation efficiency. The possible mechanism of the photocatalytic nitrogen fixation was also investigated. This study may provide a novel idea and insight for the design of efficient photocatalysts for nitrogen fixation.