Effects of TiCl₄ Surface Treatment on Photoelectrochemical Response of TiO₂ Nanotube Arrays

Abstract

TiO₂ nanotube arrays were fabricated using electrochemical anodization process and post-treated by varying the concentration of the TiCl₄ aquous solution (5 to 50 mM) for the surface treatment. Those photoelectrochemical (PEC) performances were significantly influenced by the TiCl₄ concentration. The 20 mM TiCl₄-treated TiO₂ nanotubes exhibited significantly enhanced PEC response, due to efficient passivation of the surface recombination traps. However, as the TiCl₄ concentration increased further to 50 mM, its PEC performance was reduced back, despite higher surface area. It can be attributed to the blocked voids caused by the formation of the TiO₂ nanoparticles between the TiO₂ nanotubes, because it leads to the hindered ion transport.

Keywords:

• TiO₂ nanotube
• TiCl₄ surface treatment
• photoelectrochemical response
• surface recombination trap

Acknowledgment

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (grant number 2010-0003968), and the Human Resources Development Program of Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant (No. 20104010100580) funded by the Korean Ministry of Knowledge Economy.

Prof. K.-S. Ahn and C.-J. Choi contributed equally to this work as corresponding authors.