Influence of water content on the formation of TiO2 nanotubes and photoelectrochemical hydrogen generation

Highly ordered TiO2 nanotube arrays for water splitting have been prepared by anodizing Ti sheet in ethylene glycol electrolyte. The influence of water content in electrolyte on the nanotube structure, photocurrent, photoconversion efficiency and hydrogen production was systematically investigated. The morphologies of TiO2 nanotube arrays were characterized by FESEM and the photoelectrochemical (PEC) performance was carried out by the electrochemical work station. The photocatalytic activity of TiO2 nanotubes was evaluated by hydrogen generation in a two-compartment PEC cell without any external applied voltage. The results indicated that the tube structure, tube length, photoelectrochemical properties and hydrogen production strongly depended on the water content. At higher water content, the tubular structure was destroyed and the tube length decreased, leading to the reduction of photocurrent and hydrogen production. TiO2 nanotubes anodized in 2 vol% H2O demonstrated the highest hydrogen production of 109 mu mol(cm(2) h). Moreover, based on the result, a growth model of TiO2 nanotubes anodized with different water contents was proposed in this study. (C) 2017 Elsevier B.V. All rights reserved.