Facile Preparation and High Activity of TiO₂Nanotube Arrays toward Oxygen Reduction in Alkaline Media

Abstract

Four TiO 2 electrodes have been investigated for the oxygen reduction reaction (ORR) in 2 M NaOH. Anodic oxidation of Ti-foil was used as the final or the first step in the preparation of four electrodes based on TiO 2 : amorphous (Ti/AM-TiO 2 ), two anatase forms (Ti/A400-TiO 2 and Ti/A550-TiO 2 ), and, finally, lithium-anatase form (Ti/A-Li 0.25 TiO 2 ), all of them obtained as TiO 2 nanotube arrays. The electrodes' structure was examined by Raman spectroscopy. Cyclic voltammetry and chronoamperometry were employed for the study of kinetics of ORR. Ti/A-Li 0.25 TiO 2 and Ti/A400-TiO 2 electrodes showed the highest catalytic activity for ORR with the highest cathodic peak current density and the lowest Tafel slope values. Number of electrons exchanged during ORR at TiO 2 electrodes was in the range from 2.3 to 2.8. Additionally, TiO 2 electrodes showed good stability as well as acceptable selectivity in the presence of borohydride, methanol or ethanol as typical fuels for fuel cells. Thus this study introduces a simple, low-cost preparation route of TiO 2 -based electrodes with high efficiency for ORR for energy conversion and storage applications.

Large Li-Ion Insertion Capacity of Thin-Wall Anatase TiO2 Nanotubes at 25 °C–55 °C

“…In the Raman spectrum of the TiO 2 NTs five Raman active modes are observed at 148 cm −1 (E g ), 204 cm −1 (E g ), 394 cm −1 (B 1g ), 515 cm −1 (A 1g , B 1g ) and 636 cm −1 (E g ), which correspond to the anatase phase. 40,45,46 TiO 2 NTs morphology was investigated by SEM, Figs. 2a-2b.…”

“…In the investigation our research group conducted with Ti/TiO 2 NTAs electrodes in 2 M NaOH, it was shown that lithiated anatase phase Li 0.25 TiO 2 was a better electrocatalyst for oxygen reduction reaction comparing to both anatase and amorphous TiO 2 NTs. 40 TiO 2 NTs with their tunable diameter and length can offer large exposed surface area and porosity which together with short diffusion length of Li-ion can significantly improve electrochemical performance for an anode in LIBs. The review papers of N.A.…”