Enhancement of electrochemical properties of micro/nano electrodes based on TiO₂ nanotube arrays

Titanium oxide nanotube (TiO₂ nanotube) arrays were produced by anodizing titanium foils in two different electrolytes. The first electrolyte consisted of ethylene glycol containing 0.5 wt% NH₄F and 4 vol% of distilled water to produce pure TiO₂ nanotube arrays and the second consisted of HF aqueous solution (0.5 wt%) containing 0.5% polyvinylalcohol to produce carbon doped TiO₂ nanotube arrays. The fabricated TiO₂ nanotube arrays were subsequently annealed in the atmosphere of nitrogen. The morphology and crystal structure of fabricated arrays were characterized by means of scanning electron microscopy and X-ray diffraction. The electrical conductivity and capacitance of TiO₂ nanotube arrays were investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Water contact angle and biocompatibility of fabricated nanotube arrays were investigated. The results showed that carbon doped TiO₂ nanotube arrays annealed in the atmosphere of nitrogen have higher conductivity and capacitance than those of pure arrays annealed in the same atmosphere. Doping with carbon enhances the biocompatibility and wettability of TiO₂ nanotube arrays. It has also noted that electrical conductivity and capacitance of TiO₂ nanotube arrays were directly proportional to the tube wall thickness.