Enhancement of Capacitive Performance in Titania Nanotubes Modified by an Electrochemical Reduction Method

Abstract

Highly ordered titania nanotubes (TNTs) were synthesised by an electrochemical anodization method for supercapacitor applications. However, the capacitive performance of the TNTs was relatively low and comparable to the conventional capacitor. Therefore, in order to improve the capacitive performance of the TNTs, a fast and facile electrochemical reduction method was applied to modify the TNTs (R-TNTs) by introducing oxygen vacancies into the lattice. X-ray photoelectron spectroscopy (XPS) data confirmed the presence of oxygen vacancies in the R-TNTs lattice upon the reduction of Ti 4+ to Ti 3+ . Electrochemical reduction parameters such as applied voltage and reduction time were varied to optimize the best conditions for the modification process. The electrochemical performance of the samples was analyzed in a three-electrode configuration cell. The cyclic voltammogram recorded at 200 mV s −1 showed a perfect square-shaped voltammogram indicating the excellent electrochemical performance of R-TNTs prepared at 5 V for 30 s. The total area of the R-TNTs voltammogram was 3 times larger than the unmodified TNTs. A specific capacitance of 11.12 mF cm −2 at a current density of 20 A cm −2 was obtained from constant current charge-discharge measurements, which was approximately 57 times higher than that of unmodified TNTs. R-TNTs also displayed outstanding cycle stability with 99% capacity retention after 1000 cycles.

Electrochemically Reduced Titania Nanotube Synthesized from Glycerol-Based Electrolyte as Supercapacitor Electrode

“…The specific capacitance (SC) of the samples anodized at different voltages and time was calculated based on the charge-discharge curves or CV voltammogram using Equations ( 1) and (2), respectively [9,27]:…”

“…Within these nanostructure materials, TNTs have attracted attention in energy storage due to their ability to offer high surface areas and greatly enhanced electron transfer pathways in comparison to non-oriented structures, which can lead to a higher charge propagation in active materials. Among all the methods used for the synthesis of TNTs, electrochemical anodization is the most promising method as it offers suitably grown directly-connected nanotubes on the titanium substrate that can be used directly without any binder as a supercapacitor electrode [9]. The attraction of this preparation method is because of its simplicity, cost effectiveness and flexibility in controlling the surface morphological parameters of anodized TNTs which are highly affected by anodizing conditions [10].…”

“…However, these approaches involved intensive controlled conditions such as high temperature and long reaction time. In view of this, several studies have been conducted to reduce TNTs prepared by either one step [9] or two step [24,25] anodization at constant voltage and time in ethylene glycol and in a mixture of glycerin and K 2 Cr 2 O 7 [26] via the electrochemical modification method, namely the cathodic reduction process. This simple, fast and cost effective method was reported to convert about 22% of Ti 4+ ions in TNTs' surface regions into Ti 3+ ions, as evidenced by the XPS peak of Ti 3+ 2p 3/2 [24].…”

Influence of Temperature Reaction for the CdSe–TiO2 Nanotube Thin Film Formation via Chemical Bath Deposition in Improving the Photoelectrochemical Activity

“…Nanostructured titanium dioxide (TiO 2 ) has been known as one of the most promising semiconductor materials, as it has been widely used in many applications, such as photocatalysts [1][2][3][4], photovoltaics [5][6][7][8][9][10][11], photoelectrochemical cells [12][13][14][15], supercapacitors [16][17][18][19], and sensors [20], due to its remarkable chemical, optical, and physical properties, as well as its low production cost and lower toxicity. The electrochemical anodization method has come to light, as it is proven to be the most facile and versatile method to synthesized TiO 2 nanotube thin films due to its ability to modify the morphology, diameter, and length of the nanotubes by varying the anodization parameters.…”

Capacitive performance of vertically aligned reduced titania nanotubes coated with Mn2O3 by reverse pulse electrodeposition

“…34,35 In our previous study, we modied TNTs by an electrochemical reduction method whereby oxygen vacancies were introduced into the lattice of the TNTs upon the reduction of Ti 4+ to Ti 3+ . 36 Attempts to incorporate metal oxides into the modied titania nanotubes in order to further enhance the capacitive performance of the samples have been conducted by the electrodeposition method. Electrodeposition is an advantageous method as it can control the composition and thickness of the thin lm, consumes less energy, is inexpensive, simple and can be easily implemented.…”