Synthesis of mesoporous silica-embedded TiO₂ loaded with Ag nanoparticles for photocatalytic hydrogen evolution from water splitting

Abstract

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 N₂ adsorption-desorption isotherms indicated that the silica-embedded anatase TiO₂ had obvious mesoporous structure with a BET specific surface area of 203.5 m²·g^-1. All Ag loaded silica-embedded TiO₂ composites showed a higher photocatalytic H₂-generation activity from water splitting under simulative solar light irradiation than that of TiO₂ products. The maximum H₂ 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 H₂-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.

Keywords

hydrogen production / Ag co-catalyst / mesopore / silica-embedding / TiO₂

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