Coating of anatase titania on clinoptilolite by metal organic chemical vapor deposition method: enhanced mesoporosity and photocatalytic activity

Abstract

Clinoptilolite-supported TiO2 (TiO2/CPMOCVD) has been synthesized by metal organic chemical vapor deposition method (MOCVD). Titanium precursor was evaporated at 110 °C under nitrogen flow rate to promote the surface interaction between titanium species and clinoptilolite. The effect of titanium precursor on the crystalline structure and the surface area of clinoptilolite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), transformed infrared spectroscopy (FT-IR), Raman spectroscopy, and Brunauer–Emmett–Teller measurement. XRD and SEM results indicate that TiO2 precursor interacted with the support, decreasing the crystallinity of the clinoptilolite. The analysis by FT-IR spectroscopy further confirms that the titanium species were bound to clinoptilolite through Ti–O–Si bonds. The TiO2/CPMOCVD catalyst showed a mesoporous structure with the distribution of pores in several dimensions 3.7–7.1 nm, with high specific surface area (~ 471 m2/g). MOCVD improved the adsorption capacity of the catalyst surface towards the pollutants. TiO2/CPMOCVD particles turn yellow after adsorption of salicylic acid. The development of the yellow color is a clear indication of the formation of charge transfer titanium (IV) salicylate surface complex. Photocatalytic decomposition of SA in aqueous solution was carried out using TiO2/CPMOCVD. Experimental results revealed that TiO2/CPMOCVD required shorter irradiation time (120 min) for complete decomposition of SA than commercial P25 Degussa and TiO2/CPimp (clinoptilolite-supported TiO2 using impregnation method). The TiO2/CPMOCVD can be recycled at least four times without loss in activity, indicating their magnificent stability.