Photoelectrochemical Performance of Smooth TiO₂Nanotube Arrays: Effect of Anodization Temperature and Cleaning Methods

The formation of self-organized titanium dioxide (TiO 2 ) nanotube arrays without bundling or clustering is essential for their high efficiency in photoelectrochemical (PEC) application. The present paper reports on the use of different temperatures to control the specific architecture of nanotube arrays and effective cleaning techniques to ensure the formation of clean TiO 2 nanotube surface. The wall thickness of nanotube arrays could be controlled from 12.5 nm to 37.5 nm through different anodization temperature ranging from 10°C to 80°C. Furthermore, ultrasonic cleaning combined with acetone showed the high-ordered TiO 2 nanotube arrays without morphological disorder, bundling, and microcrack problems. Based on the results obtained, a higher PEC response of 1 mA/cm 2 and a photoconversion efficiency of 1.3% could be achieved using a wall thickness of 12.5 nm and defect-free TiO 2 nanotube arrays for low charge transfer resistance.