Effect of Alcohol Sacrificial Agent on the Activity of Au/TiO₂ Nanoparticles Photocatalyst for H₂ Production Reaction and their Mechanistic Study

This study focuses on the performance of Au/TiO₂ photocatalyst for HER (Hydrogen Evolution Reaction) under UV excitation, gives an emphasis on the role of the alcohol sacrificial reagent. TiO₂ nanoparticles (NPs) with fine particle size are produced by the hydrolysis of Titanium Tetrachloride (TiCl₄) as developed by Rabani et al.¹ The resulting TiO₂-NPs were decorated with metal NPs by the addition of metal precursors followed by the reduction with sodium borohydride (NaBH₄). Photocatalytic H₂ production experiments were conducted in aqueous solutions of methanol, ethanol and isopropanol under UV illumination with an optimum alcohol concentration of around 2.0 M. The hydrogen production yields follow the order: methanol > isopropanol > ethanol. The dihydrogen production was continuously followed for 3 h. The results give a better understanding of the role of the sacrificial reagents in HER. The addition of acetone into the reaction system suppresses the H₂ formation suggesting that the alcohol oxidation product reacts with the surface reducing agents (Hydrogen atoms or hydrides or electrons). The mechanism of this catalytic system is under investigation.

References:

• Ruomei Gao, Agnes Safray, Joseph Rabani, Fundamental reactions in TiO₂ nanocrystalline aqueous solutions studied by pulse radiolysis, Radiation Physics and Chemistry 2002, 65, 599-609.