Controlling wettability of AgI/BiVO4 composite photocatalyst and its effect on photocatalytic performance

We report a simple method to modify the surface of 1:1 AgI/BiVO4 composites with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDS), 3-(methacryloyloxy)propyltrimethoxysilane (KH-570), and trimethylchlorosilane (TMCS). The physical and chemical properties of the photocatalysts before and after modification were characterized by XRD, XPS, SEM, FT-IR, UV-vis DRS, and water contact angle (WCA) measurements. After the modification, the WCA of the 1:1 AgI/BiVO4 composites increased from 34.0 degrees to 95.0 degrees (0.11 PFDS), 57.3 degrees (3.5 KH-570), and 57.0 degrees (2.5 TMCS). The surface with controllable wettability was obtained by optimizing the amount of modifier. The removal rate of 17 alpha-ethinyl estradiol (EE2) was significantly increased within a certain range of wettability. The WCA ranges of 1:1 AgI/BiVO4 composites modified by PFDS, KH-570, and TMCS were 68.3-75.8 degrees, 42.0-52.3 degrees, and 42.0-54.7 degrees, respectively, and the removal rate of EE2 was significantly higher. The photocatalytic activity was the best when the WCAs were 75.8 degrees (0.05 PFDS), 51.0 degrees (2.0 KH-570), and 48.1 degrees (1.3 TMCS), and the removal rates of EE2 in 20 min under visible light were 90.0%, 92.9%, and 99.4%, respectively. These values were significantly better than those of unmodified 1:1 AgI/BiVO4 composite (74.7%) and pristine BiVO4 (8.4%). The results show that appropriate wettability improves photocatalytic activity. (C) 2020 Elsevier B.V. All rights reserved.