Surface double modification and photocatalytic performance of graphite carbon nitride

Abstract

Graphite carbon nitride (g-C₃N₄) has attracted much attention in the field of photocatalysis because of its visible light response and stable properties. However, its photocatalytic activity is not ideal because of its limited visible light response range, easy recombination of photogenerated electron holes, and poor dispersion. In this study, the visible light catalytic performance of g-C₃N₄ was significantly improved by the double modification method of surface hydroxyl and coupling agent grafting. Firstly, g-C₃N₄ was prepared by thermal polymerization with melamine as the raw material, and then the surface hydroxyl group was introduced by hydrogen peroxide. Finally, the organic groups were grafted on the surface of g-C₃N₄ by using silane coupling agent YDH171 as the grafting agent. The catalysts were characterized by FT-IR, XPS, XRD, contact angle measurements, UV-vis DRS, PL, electrochemical methods and particle size distribution. Taking simulated oily wastewater as the target material, the reaction rate of graphite carbon nitride was increased by 2.7 times after surface double modification. Moreover, a radical trap experiment was carried out, which indicated that the hole acted as the main reactive species for the photocatalytic degradation process. The catalytic mechanism of the material was investigated. The results showed that the synergistic effect of surface hydroxyl group grafting and coupling agent grafting increased the separation efficiency of photogenerated electron holes and improves their dispersion in water, thus promoting the photocatalytic performance of the catalyst.