Insights of temperature dependent catalysis and kinetics of electro-oxidation of nitrite ions on a glassy carbon electrode

Influence of temperature on the catalysis and kinetics of nitrite oxidation reactions has been investigated on a glassy carbon (GC) electrode surface in a slightly basic medium. To elucidate the kinetics of oxidation reaction, diffusion coefficient, electron transfer coefficient, heterogeneous rate constant and free energy of activation were systematically evaluated within the temperature range of 0-60 degrees C. Nitrite oxidation involves single electron transfer and first order reaction forming nitrogen dioxide as a product. The electrode process was found most efficient at 60 degrees C with a standard rate constant (k(0)) of 4.63 x 10(-5) cm s(-1) at 0. 0.84 V vs. Ag/AgCl (sat. KCl) reference electrode. Above 60 degrees C, predominant desorption step negatively influences the overall reaction rate. It has been proposed that at the lower temperatures (>= 30 degrees C), the chemical step is concerned with an electron transfer step at the RDS and above this temperature, the reaction simply follows a stepwise mechanism. The decrease of solvent reorganization energy (lambda) at higher temperatures minimizes the activation free energy (Delta G double dagger) which accelerates the reaction rate using catalytically different route. (C) 2020 Elsevier Ltd. All rights reserved.