Effects of surfactants on the morphology and properties of TiO2

Abstract

TiO2 nanoparticles with controllable morphology perform well in both physical and chemical properties, which have great significance in photocatalytic degradation of wastewater and photodegradation of water. In this study, TiO2 was prepared by solvothermal method with tetrabutyl titanate as titanium source, acetic acid as solvent and surfactant as additive. The effects of single and mixed surfactants, such as cetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG) and carboxamide, on the microstructure of TiO2 were systematically studied. The results showed that the prepared TiO2 was anatase phase. It clearly demonstrated the procedure how the morphology and size of TiO2 were influenced by surfactant. In the reaction system, when carboxamide was added to TiO2, CTAB or PEG, TiO2 nanocrystals gathered to form rod, cluster or similar ellipse, respectively. When two or more different surfactants were added to the system simultaneously, the morphology of TiO2 could be cauliflower-like, spherical and three-dimensional flower-like structures formed by the directional aggregation of nanocrystals due to the coordination between the surfactants. The photocatalytic properties of methyl orange were investigated under UV irradiation. The results showed that the photocatalytic properties of cauliflower-like structures, spherical structures and three-dimensional flower-like structures formed by the directional aggregation of nanocrystals were better than those of commercial Degussa P25. TiO2 nanoparticles with three-dimensional flower-like structures exhibited good photocatalytic performance, with the degradation ratio of methyl orange 94% under simulated irradiation for 60 min.