Synthesis and deposition of ultrafine Pt nanoparticles within high aspect ratio TiO₂ nanotube arrays: Application to the photocatalytic reduction of carbon dioxide

Using a rapid microwave-assisted solvothermal approach ultrafine Pt nanoparticles are synthesized and deposited in situ within high aspect ratio nanotube arrays. Adjusting the initial concentration of metal ion precursor inside the nanotube support controls the resulting Pt nanoparticle sizes. The Pt-nanoparticle/TiO₂ nanotube composite is shown to greatly promote the photocatalytic conversion of carbon dioxide and water vapor into methane, a behavior attributed to the homogeneous distribution of metal co-catalyst nanoparticles over the TiO₂ nanotube array surface providing a large number of active reduction sites. The novelty and flexibility of the technique, described herein, could prove useful for the deposition of metal, metal alloy, or metal oxide nanoparticles within a variety of nanotubular or nanoporous material systems with the resulting nanocomposites useful in catalysis, photocatalysis, photovoltaic, and photoelectrochemical applications.