Optimization of surface charge transfer processes on rutile TiO2 nanorods photoanodes for water splitting

• Published in: International journal of hydrogen energy 2013-03, Vol.38 (7), p.2979-2985
• Main Authors: Fàbrega, C., Andreu, T., Tarancón, A., Flox, C., Morata, A., Calvo-Barrio, L., Morante, J.R.
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Energy; Exact sciences and technology; Fuels; Hydrogen; Impedance; Nanorod; TiO2; Water splitting
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2012.12.077

Electrochemical impedance spectroscopy (EIS) has been performed to investigate the photocatalytic properties of titanium dioxide nanorods in a photoelectrochemical water splitting system. A two-channel transmission line model has been proposed to interpret the frequency response of the main charge transfer processes that occur at nanorod/electrolyte and platinum/electrolyte interfaces. EIS was then employed to determine that the dramatic effect of the annealing treatment on the photocurrent density had its origin on a poor charge transfer at the titania/electrolyte interface. X-ray photoelectron spectroscopy and thermogravimetry measurements have been used to prove the relevance of the presence of chlorine coming from the synthesis process of TiO2 nanorods. [Display omitted] ► TiO2 nanorods exhibit high photoelectrochemical efficiency under sunlight. ► The efficiency is strongly affected by a final heat treatment step during synthesis. ► Residual chlorine species from the synthesis process block the reaction sites. ► Heating above 250 °C under O2 needed to completely remove residual chlorine species.