Preparation of SeW-codoped TiO2 nanotubes and effect of various hole scavengers on their photoelectrochemical activity: Alcohol series

Tungsten-doped TiO2, sulfur-doped TiO2 and tungsten-sulfur-co-doped TiO2 nanotubes (WTiO2, STiO2 and WS, respectively) were prepared in a one-step anodization of titanium foil for photoelectrochemical water splitting. It was found that molar ratio of the precursors [W]/[S] in anodization electrolyte could affect the morphological and photoelectrochemical properties of prepared electrodes. Sample W50S50 showed the best photoelectrochemical activity compared with the other samples and high transient photo induced current and charge carrier concentration of 124 mA cm(-2) and 2.48 x 10(22) cm(-3), respectively. The impact of various aliphatic alcohols, used as hole scavengers, on the photoelectrochemical activity of W50S50 sample was investigated. Sorbitol was the most appropriate hole scavenger, based on the results. In addition, sorbitol concentration has been optimized. The results of the current study show that the number of hydroxyl groups of the scavenger significantly affects its effectiveness in the improvement of photoelectrochemical activities. Therefore, the best results are shown by the polyhydric alcohols containing one hydroxyl group on each carbon atom. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.