Modification of TiO2 by Er3+ and rGO enhancing visible photocatalytic degradation of arsanilic acid

Authors：Ren, Xinghao; Yao, Hang; Tang, Rui; Rong, A.; Yuan, Shoujun; Wang, Wei; Ali, Ibrahim Mohamed; Hu, Zhen-Hu^*

Source：Environmental Science and Pollution Research, 2023, 30(12): 35023-35033.

DOI：10.1007/s11356-022-24627-9

• Arsanilic acid
• Er3+-rGO@TiO2
• Modification
• Photocatalytic degradation
• TiO2
• Visible light

As a typical wide band gap photocatalyst, titania (TiO2) cannot use the visible light and has fast recombination rate of photogenerated electron-hole pairs. Simultaneous introduction of erbium ion (Er3+) and graphene oxide (rGO) into TiO2 might overcome these two drawbacks. In this study, Er3+ and rGO were co-doped on TiO2 to synthesize Er3+-rGO/TiO2 photocatalyst through a two-step sol-gel method. Based on the UV-visible diffuse reflectance spectra and photoluminescence spectrum, the introduction of Er3+ and rGO increased the visible light absorption efficiency and enhanced the migration of photogenerated electron. Pure TiO2 has almost no photocatalytic activity for arsanilic acid (p-ASA) degradation under visible light irradiation. However, while doping with 2.0 mol% Er3+ and 10.0 mol% rGO, the p-ASA could be completely degraded within 50 min by the Er3+-rGO/TiO2 photocatalyst under visible light irradiation, and most of produced inorganic arsenic was in situ removed by adsorption from the solution. The reactive oxygen species (ROS) reacting with p-ASA was determined and superoxide radical (O-2(center dot-)) and singlet oxygen (O-1(2)) were the dominant ROS for the oxidation of p-ASA and arsenite. This work provides an approach of introducing Er3+ and rGO to enhance the visible light photocatalytic efficiency of TiO2.