Electrocatalytic behavior of AgBr NPs as modifier of carbon past electrode in the presence of methanol and ethanol in aqueous solution: A kinetic study

A modified carbon paste electrode (CPE) with AgBr nanoparticles (NPs) showed an increased anodic current in cyclic voltammetry (CV) when methanol or ethanol was added to the supporting HCl electrolyte at pH 2.5. This work was focused to study the kinetic aspects of the modified AgBr NPs-CPE electrode in the absence and presence of the mentioned alcohols. The electrode showed an irreversible response because difference between the peak potentials was about 135 mV and ratio of I-pa/I-pc was 0.88 for the proposed (AgBr)-Br-I/(AgBr)-Br-II redox process. The surface coverage concentration of the electrode, Gamma, was estimated about 13.0 mu mol AgBr cm(-2). The charge transfer coefficient, a, was changed from 0.72 in HCl to 0.53 and 0.61 when methanol or ethanol was added to HCl solution in CV experiments, while when Tafel plots were studied in LSV (linear sweep voltammetry) its value was changed from 0.72-0.56 and 0.67, respectively. Similarly, the rate constant value was changed from 0.34 s(-1) to 0.78 and 0.67 s(-1) in CV experiments and from 0.31 s(-1)-0.83 and 0.68 s(-1) in LSV experiments by adding the mentioned alcohols, respectively, confirming a faster reaction rate in the presence of the alcohols. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.