Synthesis, characterization, and photocatalytic activity for hydrogen evolution of nanocrystalline mesoporous titania prepared by surfactant-assisted templating sol-gel process

Nanocrystalline mesoporous titania was synthesized via a combined sol-gel process with surfactant-assisted templating method, treated under various calcination conditions, and evaluated for its photocatalytic activity through photocatalytic hydrogen evolution from an aqueous methanol solution. In this synthetic method, applied surfactant template molecules functioned as both mesopore-forming and gelation-assisting agents. The resulting products were methodically characterized by TG-DTA, XRD, N₂ adsorption-desorption, diffuse reflectance UV-Vis spectra, SEM, and TEM analyses. The partial phase transformation from anatase to rutile occurred beyond calcination temperature of 600 °C and anatase-rutile transition kinetics was also investigated. The calcination conditions and crystalline phases existing in the products exerted significant effect on the photocatalytic hydrogen evolution activity. The activity of the synthesized titania treated under appropriate calcination conditions was considerably higher than that of commercial titania powders, Ishihara ST-01 and Degussa P-25. It is clearly seen that the introduction of mesopore into titania photocatalyst substantially improved the photocatalytic performance.