Role of Cl Ion Desorption in Photocurrent Enhancement of the Annealed Rutile Single-Crystalline TiO2 Nanorod Arrays

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Original languageEnglish
Pages (from-to)18892-18899
Journal / PublicationJournal of Physical Chemistry C
Issue number34
Online published14 Aug 2017
Publication statusPublished - 31 Aug 2017


TiO2 nanorods arrays (NRAs) have been considered as very promising photoanode materials in photoelectrochemical (PEC) cells. However, the performance of TiO2 NRAs still requires substantial improvement in order to reach the goal of practical applications. Annealing treatment of TiO2 NRAs can help to improve the PEC performance, but the mechanism is still not yet fully understood. In this work, we systematically investigated the optical and electronic properties, as well as the PEC performance of the thermally treated rutile single-crystalline TiO2 NRAs. Surprisingly, we recorded a maximum photocurrent density of 1.38 mA/cm2 at 1.3 V versus reversible hydrogen electrode for TiO2 NRAs annealed in O2, which is about 28 times higher than that of the pristine TiO2 NRAs. We further revealed that the surface adsorbed Cl ions largely suppress the photoresponse of the TiO2 NRAs as they serve as recombination centers and block the adsorption of water molecules to the surface of TiO2 NRAs. The enhancement in photocurrent after annealing in O2 is due to the desorption of the Cl ions, filling of the surface Vo, expansion of the depletion layer, and increase of the grain size. Our results shed light on the effect of annealing on the PEC performance of TiO2 NRAs and offer guidance for annealing of other semiconductor materials.