Titania and Pt/titania aerogels as superior mesoporous structures for photocatalytic water splitting

Abstract

The highly porous, three-dimensionally well-connected through-pore structure of TiO₂ aerogels is proven a superior material form for applications in photocatalytic water splitting for hydrogen production. At the reaction temperature of 30 °C, the specific hydrogen evolution rate achieved by the TiO₂ aerogel is 3.40 and 9.63 times those obtained by hydrothermally prepared TiO₂ nanocrystals and commercial P25 TiO₂ nanoparticles, respectively. Decoration of Pt nanocrystals onto the backbone of the TiO₂ aerogel leads to a one-order of magnitude improvement in hydrogen evolution rate over the plain TiO₂ aerogel. Two methods are developed for the Pt decoration: a polyol process and an immersion-calcination-reduction process. The latter produces smaller sized Pt nanocrystals of around 1.9 nm, versus 4.7 nm from the polyol process, and achieves the same level of maximum specific hydrogen evolution rates as the polyol process at only a 1/10 Pt loading.