Noble-Metal-Free Zinc Oxide Nanoparticle Electrodes for Electrochemical Detection of Benzene-Derived Compounds: 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and diphenylamine

Zinc oxide nanoparticle electrode catalysts were used to electrochemically examine benzene-derived compounds by controlling geometric factors (particle size and oxide-layer thickness) to measure the detection sensitivity difference. Spin-coating was performed to control the nanoparticle layer thickness. First, a representative benzene-derived compounds (2,4,6-trinitrotoluene) was detected using cyclic voltammetry. Three main cathodic reduction peaks were confirmed in the range of −0.5 to −0.9 V (vs Ag/AgCl in 3 M KCl). 50 nm diameter and ∼2 μm thickness of zinc oxide nanoparticles appeared the best detection performance, due to the surface uniformity, high surface area, and electric conductivity. Two additional benzene-derived compounds (2,4-dinitrotoluene and diphenylamine) were utilized to measure the detectability of the zinc oxide nanoparticle layers. Consequently, 2,4-dinitrotoluene and diphenylamine were detected using cyclic voltammetry. The mass transfer of these three benzene-derived compounds affected the diffusion- and surface-controlled processes. Finally, the limits of detection, quantitation, and sensitivity of the benzene-derived compounds were recorded using differential pulse voltammetry. The results indicated that adjusting the geometric factor is a competitive method for enhancing the detection sensitivity. Moreover, this work can be extended to detect diverse benzene-derived compounds such as diazonitrophenol, nitrocellulose, picric acid, and tetryl.