Effect of Potential and Aqueous Electrolyte In Different Anode Coating Steps on the Structure and Specific Capacitance of Titanium Dioxide Nanotubes

Authors

  • Pichaya Nitnithiphrut, Varinrumpai Seithtanabutara

Abstract

We report the fabrication and electrochemical properties of anodic TiO2 nanotube arrays (TNA) formed on Ti-alloy substrate as supercapacitor electrode. Physical or chemical cleaning method was applied for surface pretreatment of Ti-alloy sheet. The single-step and triple-step of anodization were carried out in ethylene glycol electrolyte containing 0.5wt % NH4F under the applied potential of 40 and 50 V, and anodizing time for the last coating of 3 and 5 h. The influence of aqueous ethylene glycol electrolyte containing 0.5wt % NH4F and 5wt% distilled water on the morphology of TNA was compared. Annealing the as-grown TNA at 500°C transformed an amorphous phase to crystalline phase. Morphologies, crystal structure and supercapacitor performances of samples were investigated by scanning electron microscopy, X-ray diffraction and electrochemical measurement, respectively. Cyclic voltammetry was measured in 1 M H2SO4 electrolyte at -0.7 V to -0.1 V with different scan rate from 5 to 60 mV/s. Electrochemical impedance spectroscopy was investigated with the frequency ranging of 0.01 Hz to 100 kHz in the same electrolyte. Results showed that triple-step anodization of chemical-cleaned Ti-alloy sheet with 5 h of the final coating in aqueous electrolyte under applied potential of 50 V flowed by air annealing gave the well-porous dense structured TNA. Moreover, its capacitance was up to 63.73 F/g at the scan rate of 5 mV/s corresponded to the electrochemical impedance behavior.

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Published

2020-05-10

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Articles