Fabrication of IrO2 decorated vertical aligned self-doped TiO2 nanotube arrays for oxygen evolution in water electrolysis.

To fabricate effective and stable OER electrode in water electrolysis, self-doped TiO 2 nanotube arrays which has a higher electrical conductivity than pristine TiO 2 nanotube arrays was used as the support for loading IrO 2 . The self-doped TNTA was fabricated by a simple electrochemical reduction of TNTA in neutral electrolyte solution, and then IrO 2 nano particles were deposited by pulse electro-deposition method. The cyclic voltammetric behavior, electrical conductivity and micro structure of self-doped TNTA prepared at different reduction potential were characterized to obtain an optimal performance, and self-doped TNTA prepared under −1.9 V (vs. Ag/AgCl) shows the best electrochemical performance. After depositing IrO 2 , the OER activity and stability of new electrodes were also determined. Due to the enhanced electrical conductivity of support, the mass activity of IrO 2 /self-doped TNTA are 50 times higher than IrO 2 /TNTA. The OER stability of new electrode was evaluated under constant current of 5 mA/cm 2 , IrO 2 /TNTA and IrO 2 /Ti were also tested for comparison. A higher stability of IrO 2 /self-doped TNTA electrode is observed than the other two electrodes, and XPS studies indicate a lower oxidation state of Ir in IrO 2 /self-doped TNTA, this shows a possible interactions between IrO 2 and the new support. [ABSTRACT FROM AUTHOR]