Au/TiO2 photocatalysts prepared by solid grinding for artificial solar-light water splitting

Abstract

Here we show in an innovative way that solid grinding is a simple and alternative method for the preparation of solar-light active Au/TiO₂ photocatalysts. We use, for the first time in the solid grinding method, triphenylphosphine gold(I) chloride (AuPPh₃Cl), which has recently been used in solution-based gold catalysts preparation, and chloroauric acid (HAuCl₄), instead of dimethyl gold(III) acetylacetonate [Me₂Au(acac)] as gold precursor. Both compounds yield Au/TiO₂ nanocomposites with interesting activity for artificial solar-light water splitting. In this paper we establish that solid grinding approach to elaborate Au/TiO₂ photocatalyst leads to better photocatalytic activity toward artificial solar light water splitting than using chemical reduction method. Effects of the gold loading, of the gold precursor and of the calcination temperature on the photocatalytic activity are described and discussed. The impact of calcination temperature is highlighted; calcination at 400 °C is found to be the optimal temperature leading to a strong interaction and intimate contact between Au and TiO₂ nanoparticles, thus allowing beneficial electronic effects.