A Simple and Rapid Method of Forming Double-Sided TiO2 Nanotube Arrays

Highly ordered TiO2 nanostructures, known as nanotube arrays (NTAs), exhibit potential in various energy, chemical sensing, and biomedical applications. Owing to its simplicity and high degree of control, titanium anodization serves as the prevailing NTA synthesis method. However, the practicality of this approach is marred by sluggish and inconsistent growth rates, on the order of 10 nm min(-1). Growth rates strongly depend on the electrolyte conductivity, yet most reports neglect to consider this property as a measured and controllable parameter. Here, we have systematically determined a broad set of conditions (at 60 V applied potential, elevated temperatures) that allow researchers to fabricate NTAs quickly and simply. By modulating conductivity through variation of bulk electrolyte temperature and the controlled addition of several hydroxy acid species, we achieve consistent accelerated growth up to 10 times faster than traditional methods. We find that regulating the solution conductivity within a desired region (e. g., similar to 800-1000 mu S cm(-1)) enabled the fabrication of double-sided NTA layers of around 10 mu m and 90 mu m NTA in 10 and 180 min, respectively.