High temperature and water-based evaporation-induced self-assembly approach for facile and rapid synthesis of nanocrystalline mesoporous TiO2

Abstract

Various appealing applications of mesoporous TiO₂ continuously spur research on related mesostructural design as well as innovations in preparation. This paper reports a novel high temperature and water-based evaporation-induced self-assembly (HW-EISA) approach based on a simple ternary templating system (peroxotitanic acid/P123/H₂O), enabling the facile and rapid synthesis of nanocrystalline mesoporous TiO₂ with unusual structures: high surface areas (140–240 m² g⁻¹), ultra-large mesopores (20–30 nm)/pore volumes (0.7–1.0 cm³ g⁻¹) and tunable bicrystallinity (anatase plus rutile). The unusual templating and subsequent decomposition behaviors of P123 were newly unveiled to play crucial and multiple roles in inducing self-assembly between peroxotitanic acid and P123 for final meso-TiO₂ with ultra-large mesopores/pore volumes during the HW-EISA and helping preserve the integrity of mesostructures during calcination and rendering bicrystallinity in the titania frameworks as well. Other PEO-based nonionic surfactants were also demonstrated to be applicable in producing similar mesostructures. The photocatalytic testing results showed that both high surface areas and the synergistic effects of bicrystallinity of anatase plus rutile are of great significance in enhancing the photocatalytic properties of meso-TiO₂.