Au-TiO2 Nanocomposites and Efficient Photocatalytic Hydrogen Production under UV-Visible and Visible Light Illuminations : A Comparison of Different Crystalline Forms of TiO2

Abstract EN

Au(~1 wt%)/TiO2(anatase or rutile or P25) nanocomposites were prepared by the solvated metal atom dispersion (SMAD) method, and the as-prepared samples were characterized by diffuse reflectance UV-visible spectroscopy, powder XRD, BET surface analysis measurements, and transmission electron microscopy bright field imaging.

The particle size of the embedded Au nanoparticles ranged from 1 to 10 nm.

These Au/TiO2 nanocomposites were used for photocatalytic hydrogen production in the presence of a sacrificial electron donor like ethanol or methanol under UV-visible and visible light illumination.

These nanocomposites showed very good photocatalytic activity toward hydrogen production under UV-visible conditions, whereas under visible light illumination, there was considerably less hydrogen produced.

Au/P25 gave a hydrogen evolution rate of 1600 μmol/h in the presence of ethanol (5 volume %) under UV-visible illumination.

In the case of Au/TiO2 prepared by the SMAD method, the presence of Au nanoparticles serves two purposes: as an electron sink gathering electrons from the conduction band (CB) of TiO2 and as a reactive site for water/ethanol reduction to generate hydrogen gas.

We also observed hydrogen production by water splitting in the absence of a sacrificial electron donor using Au/TiO2 nanocomposites under UV-visible illumination.