Methyl salicylate detection via electrochemical transients using nano spinel Co3O4 films

• Co3O4 films were fabricated for electrocatalytic oxidation of methyl salicylate.
• Overall electrodeposition process is under diffusion control.
• Oxidation of salicylate di-ion into 1, 2 benzoquinone is more favorable.
• Estimated anodic transfer coefficient is 0.42, with four-electron transfer.
• The rate of oxidation is retarded by activation polarization potential.

The mixed nano spinel Co3O4 films were fabricated through electrochemical deposition followed by peroxide oxidation and heat treatment. Electrochemical characteristics of the deposition and textural as well as morphological characteristics of the films were analyzed. Both 400 plane for Co3O4 and the 200 plane for CoO were noted. Based on IR studies, hydroxides decomposed into oxides on annealing. Oxide films are having the stoichiometric atomic weight ratio, O:Co as 1:2.7. Chronopotentiometric and chronoamperometric transients were recorded for the anodic oxidation of methyl salicylate using cobalt oxide films. Based on the electrochemical kinetic data, oxidation mechanism scheme is proposed and the net oxidation rate depends on sluggish charge-transfer limitations. Salicylate di-ion to 1, 2 benzoquinone is more favorable than 1, 4 benzoquinone derivative with four-electron transfer, whereas methoxide to formaldehyde involves two-electron transfer.