Study of kinetics aspects of the electrocatalytic oxidation of benzyl alcohol in aqueous solution on AgBr modified carbon paste electrode

Abstract

When a modified carbon paste electrode (CPE) with AgBr nanoparticles was immersed in a HCl supporting electrolyte at pH 3.5, it showed a well redox peak pair in cyclic voltammetry (CV) (Epa: 220 mV, Epc: 119 mV). Its anodic peak current was increased when benzyl alcohol (BZ) was added into the solution. The electrode response showed an irreversible behavior because the Epa-Epc difference was 109 mV and Ipa/Ipc = 1.09 for the AgIBr/AgIIBr redox process. The electrode had a geometric surface area of 0.03 cm2, while its effective surface area was estimated about 0.16 cm2. The Γ value, the surface coverage concentration of the electrode, was about 10.5 μmol AgBr cm−2. While the charge transfer coefficient, α, was 0.67 in HCl in CV experiments, but it was changed to 0.61 when BZ alcohol was added into the solution. α- values of 0.63 to 0.58 were obtained by Tafel plots in LSV (linear sweep voltammetry) in the absence and presence of BZ alcohol, respectively. The rate constant value (k) was changed from 0.21 s−1 to 0.55 s−1 in CV experiments and from 0.33 s−1 to 0.43 s−1 in LSV experiments by addition of BZ alcohol into the solution, confirming a faster reaction rate in the presence of BZ alcohol.