Electrochemical Analysis of Bromine‐Treated Titanium Dioxide Nanotubes for Supercapacitor Applications

ABSTRACT In this study, we report the effect of bromine treatment on electrochemically synthesized TiO 2 nanotube (TNT) electrodes for supercapacitor applications. The bromine‐treated TNT electrodes, exhibiting an anatase crystal structure, showed a sixfold enhancement in specific capacitance compared to untreated TNTs, achieving a high gravimetric specific capacitance of 330 F g −1 and an areal specific capacitance of 135.59 mF cm −2 at a current density of 2.5 mA cm −2 . Furthermore, the electrodes demonstrated exceptional cycling stability, retaining 100% of their capacitance after 5200 charge–discharge cycles. This remarkable performance enhancement is attributed to the generation of oxygen vacancies within the anatase lattice upon bromine treatment, along with a significant reduction in charge transfer resistance at the electrode–electrolyte interface. The material properties of the electrodes were comprehensively characterized using x‐ray photoelectron spectroscopy, transmission electron microscopy, field‐emission scanning electron microscopy, x‐ray diffraction, and Raman spectroscopy. In addition, a prototype symmetric supercapacitor fabricated using the bromine‐treated electrodes delivered a specific capacitance of 36.3 F g −1 at a scan rate of 5 mV s −1 , a power density of 3.69 kW kg −1 and a capacitance retention of 100% over 2000 cycles.