Facile Synthesis of Highly Supercapacitive Mo-doped Titanium Nanotube Arrays and Effect of Anodization Voltage

Designing potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo-doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100  V, TNT and Molybdenum-doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm⁻² respectively, at a current density of 1 mA cm⁻². Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm⁻² and a power density of 799.99 µW cm⁻² could be achieved with this sample in an asymmetrical device.