Journal of Electroanalytical Chemistry, Vol.779, 199-206, 2016
Frequency-dependence of electric double layer capacitance of TiO2-based composite nanotube arrays
The electric double layer capacitances for a series of titanium dioxide based composite nanotube-arrays (TNTAs, Pt/TNTAs, CdS/TNTAs, CdS/Pt/TNTAs) in aqueous solutions were examined at the polarized potential. As a result, the capacitance increases with a decrease in the ac-frequency, obeying the inverse of the power law of the frequency. The power law is demonstrated to be equivalent to the constant phase element. The intensity of frequency dispersion varies with nanoarrays as to different nano architectonics and materials. The CdS coated TNTAs yield the largest specific capacitance of 2.33 mF cm(-2) at a frequency of 1 Hz, which is about 9 times higher than the capacitance obtained from bare TNTAs at the same condition. The coating of Pt, however, shows less capacitive behavior with more obvious frequency-dispersion. (C) 2016 Published by Elsevier B.V.
Keywords:Double layer capacitance;Composite nanotube arrays;Frequency-dispersion;Constant phase element