Carbon black on ordered scaffold of titania nanotubes as smart nanoengineered material for the next generation of highly sensitive electrode

This study presents the first three-electrode system, which combines the extensive nanostructured surface of hydrogenated TiO₂ nanotubes and the electrochemical properties of carbon black to develop an electrochemical sensor with a nanoengineered surface. The use of TiO₂ nanotubes as a substrate allowed for the deposition of a high amount of carbon black up to 120 μg per cm² on the electrode surface without observing an undesired aggregation encountered in the case of other sensors. Electrochemical measurements revealed that the increase of carbon black amount improved electrode performance, showing the lowest peak-to-peak separation (240 mV) and the highest current density (1.63 mA cm⁻²). Electrochemical impedance spectroscopy demonstrated that the carbon black-modified hydrogenated TiO₂ nanotube electrode exhibited lower charge transfer resistance (52.88 Ω) than the unmodified electrode (12,290 Ω). The performance of both the hydrogenated TiO₂ nanotube electrode and the optimized carbon black modified-electrode was evaluated for the detection of model analytes namely epinephrine, norepinephrine, benzoquinone, catechol, ascorbic acid, and caffeic acid. The results demonstrated an improved electrochemical response, emphasizing the enhanced detection capabilities achieved by integrating carbon black on the TiO₂ nanotube structure. This modification opens new possibilities for the development of highly sensitive electrochemical sensors by engineering the electrochemical surface before the modification of the working electrode surface with carbon black.