Nano-Asterisks of Vanadium Dioxide As Electrodes for TNT Detection
To make nano-asterisks of VO2, the amount of vanadium precursor present during a hydrothermal treatment was varied to produce several different morphologies of VO2(M) including plates, snowflake asterisks, and truncated asterisks. Films of the particles were drop cast onto glass slides and four-point Van der Pauw resistivity measurements were used to determine the phase transition behavior of the particle films. We observe resistivity changes of more than 2 orders of magnitude for drop cast films of VO2(M) nano-asterisks. Additionally, BET gas adsorption theory was used to determine the surface area of the particles in order to evaluate their potential as electrocatalytic materials.
The electrochemical reduction of 2, 4, 6-Trinitrotoluene (TNT) was investigated using films of vanadium dioxide, from both thin layer films formed by PLD and films composed of nano-asterisks particles. Three distinct reduction peaks were observed in the potential range -0.50 V to -0.90 V (vs. an Ag/AgCl reference electrode), corresponding to the electrochemical reduction of the three nitro-groups on the TNT molecule. Adsorptive stripping voltammetry was performed to achieve detection down to 1 µg/L (4.4 nM), revealing a linear response to TNT concentration. These results are the first describing the use of VO2 films as an electrochemical sensor for TNT, and open new avenues for further electrochemical research using this unique material.