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

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 degrees 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.