Hydrothermal synthesis of mesoporous TiO2 using β-diketonate stabilizing agents for photocatalytic degradation of methyl violet 2B under visible light

Abstract

Mesoporous TiO2 (m-TiO2) has gained much attention in various industrial fields because of its good photosensitivity and nontoxicity. In this study, we investigated the effect of stabilizing agents on the surface area and porosity of m-TiO2. m-TiO2 was synthesized via a soft-template-assisted hydrothermal method using four different β-diketonate stabilizers. With the electron-donating group in β-diketones, the particle size of m-TiO2 decreased and its surface area increased because of increased substitutions with alkoxyl or alkyl groups. Among the m-TiO2 spheres prepared using the four stabilizers, m-TiO2(3MP), which had the highest pKa value of 3MP, exhibited the most uniform and smallest particle size because of the greater number of electrons in its CO bonds for bonding with Ti cations. The prepared m-TiO2 catalysts were evaluated for the photocatalytic degradation of methyl violet 2B (MV) under UV and visible light. m-TiO2(3MP) resulted in the highest degradation and reaction rates, 0.0189 min−1 (UV) and 0.0232 min−1 (visible), which was superior activity than commercial TiO2 (P25). These results indicate that the stabilizing agents affect the formation of m-TiO2 and the largest surface area leads to the highest photocatalytic activity.