Synthesis of Mesoporous Silica-Embedded TiO_2 Loaded with Ag Nanoparticles for Photocatalytic Hydrogen Evolution from Water Splitting

摘要

Ag loaded mesoporous silica-embedded TiO_2 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(OC_4H_9)_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 TiO_2 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 TiO_2 had obvious mesoporous structure with a BET specific surface area of 203.5 m^2·g^(-1).All Ag loaded silica-embedded TiO_2composites showed a higher photocatalytic H_2-generation activity from water splitting under simulative solar light irradiation than that of TiO_2 products.The maximum H_2 production rate(6.10 mmol·h^(-1)·g^(-1)) was obtained over 2%Ag/silica-embedded TiO_2 nanocomposites(2%Ag/MST) prepared by solvothermal-chemical reduction method,which was 20 times that achieved on the silica-embedded TiO_2 sample.The enhanced photocatalytic H_2-evolution activity of Ag loaded mesoporous silica-embedded TiO_2 nanocomposites can be attributed to the multi-function of surface Ag co-catalyst,mesoporous structure,and embedding of silica.