Photocatalytic H2 Generation Using Dewetted Pt-Decorated TiO2 Nanotubes: Optimized Dewetting and Oxide Crystallization by a Multiple Annealing Process

Abstract

In the present work we use TiO2 nanotube arrays, deposit onto them a thin layer of Pt, dewet the Pt to nanoparticles, and use the structures as photocatalyst to generate H2. In order to achieve a maximum H2-generation efficiency, on the one hand an optimal thermal dewetting of the Pt layer is needed (this requires an oxygen-free heat treatment), and on the other hand an optimal crystallization of the TiO2 nanotubes into a suitable crystalline oxide is required (achieved by annealing in an O2-containing environment). To combine the two requirements, we provide an adequate multiple annealing treatment under reducing and oxidizing conditions and obtain Pt-nanoparticle-decorated TiO2 nanotubes, composed of an anatase-rutile mixed phase, that show a significantly enhanced photocatalytic H2 generation ability compared to tube layers that underwent any single-step annealing process.