Effect of Thermal Treatment of Symmetric TiO[sub.2] Nanotube Arrays in Argon on Photocatalytic CO[sub.2] Conversion

Symmetric titania nanotube arrays (TiO[sub.2] NTs) are a well-known photocatalyst with a large surface area and band edge potentials suitable for redox reactions. Thermal treatment of symmetrical arrays of TiO[sub.2] nanotubes in argon was used to change the carbon content of the samples. The influence of the carbon content in the structure of symmetrical TiO[sub.2] NTs on their photoelectrochemical properties and photocatalytic activity in the conversion of CO[sub.2] into organic fuel precursors has been studied. The structure, chemical, and phase composition of obtained samples were studied by X-ray analysis, Raman spectroscopy, and SEM with energy dispersive analysis. It is established that carbon-related defects in the samples accumulate electrons on the surface required for the CO[sub.2] conversion reaction. It has been shown for the first time that varying the carbon content in symmetric TiO[sub.2] NTs arrays by annealing at different temperatures in argon makes it possible to control the yield of methane and methanol in CO[sub.2] conversion. It is revealed that too high a concentration of carbon dangling bonds promotes the growth of CO[sub.2] conversion efficiency but causes instability in this process. The obtained results show a high promise of symmetric carbon-doped TiO[sub.2] NTs arrays for the photocatalytic conversion of CO[sub.2].