Alkali Hydrothermal Treatment to Synthesize Hydroxyl Modified g-C3N4 with Outstanding Photocatalytic Phenolic Compounds Oxidation Ability

Abstract

The treatment of phenol-containing wastewater is a hot topic in the field of environmental chemistry. In this work, the hydroxyl grafted graphite phase carbon nitride (g-C3[Formula: see text] was prepared by alkaline hydrothermal (AH) treatment, and its degradation of phenol under visible light was investigated. XRD, UV-Vis, FT-IR, XPS, N2 adsorption, PL, ESR, TPD and EIS were used to characterize the as-prepared catalysts. The results showed that the hydroxyl group grafting does not influence the crystal structure, optical property and specific surface area of catalyst. Compared with the hydroxyl group modified g-C3N4 prepared by H2O2 method, the alkali hydrothermal treatment can graft more hydroxyl groups onto the g-C3N4 surface, leading to the higher electron–hole separation efficiency. The as-prepared catalyst using this method had more surface negative charges and stronger adsorption capacity for the reaction substrate phenol. The g-C3N4 prepared by this alkali hydrothermal treatment displayed the phenol degradation rate constant of 0.22[Formula: see text]h[Formula: see text], which is 3.72 and 2.06 times higher than that of neat and H2O2 treated g-C3N4, as well as excellent catalytic stability and structural stability. The possible reaction mechanism was proposed.