Effect of Doping on TiO₂ Nanotubes Based Electrochemical Sensors: Glucose Sensing as a Case Study

Abstract

This work highlights the influence of the electrochemical doping on TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes (T-NTs) based electrochemical sensor. Two working electrodes, namely plain T-NTs and WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> doped T-NTs (T-NTs -WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ), both embedded with Ni(OH) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles (Ni-NPs) were chemically synthesized, thoroughly characterized and their performances were compared for sensing glucose. The Ni-NPs embedded T-NTs - WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> device outperformed the Ni-NPs embedded with undoped T-NTs by having low detection limit of 30 μM and excellent selectivity (with respect to ascorbic acid and uric acid) towards sensing glucose. The superior performance was ascribed to the synergetic effect of the defect induced states of WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> dopant with active Ni(OH) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> electro catalyst, which enhances the electron transfer rate, thereby increasing the conductivity, leading to 6 times higher sensitivity and 4.5 times lower limit of detection, indicating the efficacious role of dopants to realize enhanced T-NTs based electrochemical sensors. The doped sensor demonstrated a very good sensitivity of 70 μA mM <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> showing higher electrocatalytic activity towards glucose oxidation. Overall, the strategy presented here, opens avenues for the development of highly efficient T-NTs based electrochemical sensors.