Synthesis of Mesoporous Silica-Embedded TiO2 Loaded with Ag Nanoparticles for Photocatalytic Hydrogen Evolution from Water Splitting

Ag loaded mesoporous silica-embedded TiO2 nanocomposites were successfully synthesized via two different routes, including one-pot solvothermal method and solvothermal-chemical reduction method, both using Titanium (IV) n-butoxide (Ti(OC4H9)(4)) as a precursor, formic acid as a solvent and reducing agent, silver nitrate as a silver source and tetraethyl silicate (TEOS) as a stabilizer. The transmission electron microscopic (TEM) images showed that silica-embedded anatase TiO2 sample exhibited approximately rhombic shape and Ag nanoparticles could be embedded into the nanocomposites or deposited on the surface with high dispersion. The N-2 adsorption-desorption isotherms indicated that the silica-embedded anatase TiO2 had obvious mesoporous structure with a BET specific surface area of 203.5 m(2).g(-1). All Ag loaded silica-embedded TiO2 composites showed a higher photocatalytic H-2-generation activity from water splitting under simulative solar light irradiation than that of TiO2 products. The maximum H-2 production rate (6.10 mmol.h(-1).g(-1)) was obtained over 2% Ag/silica-embedded TiO2 nanocomposites (2% Ag/MST) prepared by solvothermal-chemical reduction method, which was 20 times that achieved on the silica-embedded TiO2 sample. The enhanced photocatalytic H-2-evolution activity of Ag loaded mesoporous silica-embedded TiO2 nanocomposites can be attributed to the multi-function of surface Ag co-catalyst, mesoporous structure, and embedding of silica.