2019/10/1 · In this study, 0.1 M nitric acid (HNO 3) (Sigma-Aldrich, UK) was used as a catalyst and the volume ratio for TBOT: EtOH: 0.1 M HNO 3 was 1: 40: 2. Then 1.0–2.0 g/L TiO 2 nanoparticles (anatase, <25 nm, Sigma-Aldrich, UK) and 2.0 g/L of PTFE particles with a mean particle size of 200–300 nm (Polysciences, Inc., USA) were introduced into the sol and thoroughly mixed by ultrasonication.