Disordered Mesoporous TiO2−xNx+Nano‐Au: An Electronically Integrated Nanocomposite for Solar H2 Generation

Abstract

AbstractWe report on H2 generation by photocatalysis driven by simulated white light by electronically integrated Au nanoparticles with multifunctional, disordered mesoporous TiO2−xNx (Au‐NT) nanocomposites. Solar H2 generation (1.5 mmol h−1 g−1) from aqueous methanol has been demonstrated with Au‐NT nanocomposites. The water splitting activity of Au‐NT is attributed to the 21.1 ps lifetime of charge carriers observed from fluorescence lifetime measurements, which indicates a high electron‐injection efficiency from nano‐Au to the conduction band of TiO2, and hence charge separation as well as utilization. This is directly supported by the observation of a high photoluminescence emission intensity with Au‐NT that highlights the energy transfer from nano‐Au to TiO2. The p–n heterojunction observed between the Au (0 0 1) and TiO2 (1 0 1) facets helps towards the higher charge separation and their utilization. A low mesochannel depth (<10 nm) associated with disordered mesoporous TiO2−xNx helps the charge carriers to move towards the surface for redox reactions and hence charge utilization. Visible‐light absorption, as a result of the surface plasmon resonance of nano‐Au, is observed in a broad range between 500 and 750 nm, which helps in harvesting visible‐light photons. Finally, electronically integrated nano‐Au with TiO2−xNx in Au‐NT is evident from Raman and X‐ray photoelectron spectroscopy measurements. All of these factors help to achieve a high rate of H2 production. It is likely that a higher rate of H2 production than that reported here is feasible by strategically locating Au clusters in porous TiO2 to generate hot spots through electronic integration.