Assembling of TiO₂ Nanotube Photoelectrodes with Enhanced Visible Properties for a Sustainable Production of H₂

Abstract

In this contribution we report on the preparation of advanced TiO2/Ti photoelectrodes to be used in photoreactors for H2 production by water photoelectrolysis and ethanol photoreforming. The highly ordered TiO2 nanotube arrays were synthesized by anodic oxidation of Ti foils applying a constant voltage in the range 40-70 V. Metal nanoparticles of noble (Au) and non-noble (Cu) metals were deposited on the TiO2 surface by photodeposition method to enhance visible light photoresponse. The TiO2/Ti photoelectrodes were fully characterized by Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy (SEM-EDX), UV- Visible Diffusive Reflectance Spectroscopy and Chronoamperometry. Then, they were tested within our homemade photoreactors (a gas photoreactor and a photoelectrochemical reactor) in water photoelectrolysis and ethanol photoreforming for H2 production. A solar simulator, equipped with a set of filters, was used to evaluate their photoresponses in different light absorption regions (ultraviolet or visible part). The results showed high performances of these photoelectrodes under visible light irradiation, depending on the nature of the doping nanoparticles onto the titania surface, opening the route of a feasible implementation of these solar devices in the sustainable production of energy.