Modification of ZIF-8 nanocomposite by a Gd atom doped TiO2 for high efficiency photocatalytic degradation of neutral red dye: An experimental and theoretical study

Abstract

The sol–gel method was used to prepare the rare earth element Gd-doped TiO2, and the solvothermal synthesis method was used to prepare ZIF-8@TiO2 (0.3% Gd). A neutral red solution was used as the degradation object to evaluate the photocatalytic degradation ability of the material. The structure, element distribution, crystallite morphology, specific surface area, element valence, light response range, and electrochemical properties of the material were analyzed by XRD, EDX, SEM, TEM, BET, XPS, UV–Vis, and EIS. The neutral red solution was degraded by a photocatalytic test. The effects of the Gd doping amount, initial concentration of the neutral red solution, photocatalyst dose, and recycling times on the catalytic efficiency were tested. The results show that TiO2 (0.3% Gd) has an anatase structure, and Gd element doping inhibits crystal growth. The composite of ZIF-8 and TiO2 (0.3% Gd) dramatically improves the specific surface area of the material. When Gd is doped in TiO2, the UV diffuse reflectance curve is shifted by a redshift. After 0.3% Gd (molar ratio), doped TiO2 has the best photocatalytic degradation effect of neutral red. ZIF-8@TiO2 (0.3% Gd) UV irradiation for 1 h, the degradation rate of neutral red was 96.55%. The optimum concentration of the neutral red solution is 20 mg/L. After four times of recycling, the catalytic efficiency is 69.41%. The content of total organic carbon after photocatalysis was analyzed, and the degradation products of neutral red dye were analyzed. The main active substances in the process of photocatalysis are analyzed, and the principle of photocatalysis is expounded. This work provides a new strategy for the field of photocatalytic degradation of organic pollutants.