Sono-dispersion of TiO2 nanoparticles over clinoptilolite used in photocatalytic hydrogen production: Effect of ultrasound irradiation during conventional synthesis methods

Abstract

Hydrogen evolution via water splitting was investigated over the sonochemically synthesized TiO2-clinoptilolite photocomposites. To this aim, a series of photocatalysts containing 10wt% titania were prepared by impregnation and solid state dispersion (SSD) methods in the presence and absence of ultrasound irradiation. The samples were characterized by XRD, FESEM, EDX, BET, FTIR, PL and UV–vis techniques and tested for the water splitting. The characterization results indicated that ultrasound irradiation endowed the photocatalysts with uniform morphology, higher surface area and more homogenous dispersion. In addition, the analyses also exhibited less population of particle aggregates, a strong titania-support interaction and lower electron-hole pairs recombination rate. These features were more prominent when ultrasound was employed during SSD method. The TiO2/Clinoptilolite photocatalyst prepared by the ultrasound assisted SSD method (TiO2/CLT(US)), had more uniform active sites dispersion, high separation efficiency of electron–hole pairs and as a consequence, high surface density of active sites. The highest photocatalytic activity, 569.88μmol/gTiO2·h, was obtained for the TiO2/CLT(US) sample which was about 8 times more than that of P-25 as a reference sample. Furthermore, the TiO2/CLT(US) photocomposite as optimal photocatalyst showed sufficient reusability, making it a good choice for photocatalytic water splitting applications.