Effect of Tin+ defects on electrochemical properties of highly-ordered titania nanotube arrays

In this paper, highly-ordered TiO 2 nanotube (TNT) electrodes fabricated by anodization at 20 V in 0.1 M F − -based solution were annealed in O 2 , N 2 and CO respectively. The surface properties of the TiO 2 electrodes after annealing treatment by different gases were studied by means of photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the TNT electrodes were investigated by cyclic voltammetry, steady-state polarization and photocurrent response measurements. The results showed that Ti n+ (n = 0–3) cations and oxygen vacancies existed in the TNT electrode after annealing in CO, leading to a very efficient electron transfer rate of 1.34 × 10 − 3 cm/s. Steady-state polarization measurement and photocurrent response demonstrated that the electrode potential of oxygen evolution reaction (OER) reduced by 20% and the photocurrent response increased by 50% for CO-annealed TNT electrode compared with O 2 -annealed TNT electrode.