On the impact evaluation of various chemical treatments of support on the photocatalytic properties and hydrogen evolution of sonochemically synthesized TiO2/Clinoptilolite

The water splitting process for hydrogen production was investigated over a series of TiO2-deposited Clinoptilolite photocatalysts assessing the individual and synergistic effects of acid/alkaline and ion exchange treatments of Clinoptilolite as a support on the physicochemical properties and photocatalytic performance. The as-synthesized photocatalysts were characterized by XRD, BET, FESEM, EDX, FTIR, PL, and UV-vis techniques. Based on the FESEM, EDX and BET techniques, higher dispersion of Ti species and an increased accessibility of the micro-channels could be achieved using modified Clinoptilolite supports due to their better textural properties. The fine dispersion of TiO2 particles reflects higher surface density of active sites and separation efficiency of electron-hole pairs, which accounts for their better photocatalytic performance. The characterization results generally indicated the remarkable synergetic effect of alkaline treatment on the surface morphology and TiO2 dispersion, especially when it is coupled with NH4NO3 treatment. The photocatalytic tests illustrated that employing the treated Clinoptilolite supports increases the photocatalytic activity up to 12-57%. It was found that TiO2 supported on the alkaline Clinoptilolite followed by NH4NO3 treatment effectively splitted water to hydrogen by 896.8μmolgTiO2−1h−1 hydrogen production rate. The results indicate that the ion exchange-alkaline treatment of Clinoptilolite could provide strong basic sites and mesopore structure (average pore diameter of 21.65 nm) with high surface area (73.43 m2 g−1) and well dispersion ability to improve the photocatalytic activity of TiO2/Clinoptilolite composite for hydrogen evolution.