Fabrication of Titania Nanotube Arrays in Viscous Electrolytes

This study probes the dependence of titania nanotube arrays nanoarchitecture on different synthesis parameters in viscous electrolytes. Titania nanotube arrays were synthesized in glycerol, ethylene glycol and carboxymethylcellulose as base materials. The effects of anodization voltage and time, as well as chemical composition and pH of the electrolyte bath were studied. Nanotube arrays with an inner diameter ranging from 16 to 91 nm, and wall thickness ranging from 7 to 29 nm were fabricated in a glycerol–water electrolyte. Water content of 5 wt% or higher was found to be essential for nanotubes fabrication in glycerol electrolyte. Diameter and length were influenced by varying water content above 5 wt%. Nanotube length was found to be time dependent at high pH values. A pH value of 6 was favorable for fabrication of highly ordered and continuous nanotube arrays with length up to 900 nm. Using modified ethylene glycol (containing 2 wt% and 0.5 wt% NH₄F) instead of glycerol, resulted in nanotube length up to 430 nm after 1.5 hr anodization time. With a minor modification of electrochemical anodization cell, we successfully fabricated double-sided titania nanotube arrays layers with a total thickness of 9.5 μm for the first time. Nantube arrays were successfully fabricated in 2 wt% sodium carboxy mythylcellulose aqueous electrolyte (CMC electrolyte). These nanotube arrays had an inner diameter of 42 nm similar to those fabricated in 2 wt% urea–ethylene glycol electrolyte but their length was 450 nm.