Photocatalytic H2 Evolution: Dealloying as Efficient Tool for the Fabrication of Rh-decorated TiO2 Nanotubes

Abstract

In this work, we report on a facile and novel method for decorating titanium dioxide (TiO2) nanotubes with Rh nanoparticle-nanonetworks that act as co-catalysts in photocatalytic H2 generation. In a first step, a Ti−Rh (0.2 at%) alloy is etched in Kroll's solution leading to a dealloyed surface decorated with a Rh nanoparticle-network of adjustable geometry and loading. By subsequent anodization of the alloy samples, Rh:TiO2 nanotubes can be grown where the tube mouths are strongly decorated with the Rh nanoparticle network (RhNw). As evident from X-ray photoelectron spectroscopy (XPS) analysis, these Rh oxide Nws are converted to metallic Rh under UV irradiation. As a result, with time a steady increase of the H2 evolution from the RhNw decorated TiO2 nanotubes is observed. Nanotubes carrying RhNw yield in photocatalytic experiments a 5-times higher H2 evolution activity in comparison with nanotubes decorated by conventional Rh-sputtering (the same loading), and show a 228 times higher activity than pristine TiO2 nanotubes.