Surface engineering of titanium dioxide nanotube electrodes <i>via in situ</i> carbon incorporation for enhanced supercapacitance

Titanium dioxide (TiO₂) is an attractive electrode material for supercapacitors due to its high surface area, good chemical stability, and relatively low cost, although its poor conductivity remains the major limiting factor. This can limit the rate at which charges can be stored and released in the electrode, affecting the overall performance of the supercapacitors. Herein, we have incorporated carbon in one of the practical ways to explore the potential of TiO₂ as the capacitance of supercapacitors is directly related to the surface area. The electrochemically fabricated titanium dioxide nanotubes infused with carbon have an enhanced surface area and improved performance due to their exceptional ability to store charge and conduct electricity like a metal. At the nanoscale, incorporating carbon dopants into a crystal lattice of titanium dioxide by ultrathin coating on the surface improves its characteristics significantly. The meticulous control of dopant concentration within the TiO₂ lattice enables precise adjustment of the carrier density. A comprehensive characterization study using XRD, HRSEM, HRTEM, Raman, and XPS techniques was employed to elucidate the influence of carbon dopants on the TiO₂ lattice structure. Contact angle measurement was recorded to understand the wettability of the electrode material in different systems. At a current density of 0.1 mA cm^-2, the electrode examined in 1 M HCl had a stunning areal capacitance of 21.125 mF cm^-2. Following electrochemical characterization, surface studies have been conducted to understand the comprehensive view of the electrode's functionality and structural availability. The investigation reveals the promising application of carbon-coated samples as high-performance electrode materials for supercapacitors.