Catalytic Adsorptive Stripping Voltammetry of Molybdenum: Redox Kinetic Measurements

Abstract

AbstractThe electrode mechanism of Mo(VI) reduction was studied under catalytic adsorptive stripping mode by means of square‐wave voltammetry (SWV). Mo(VI) creates a stable surface active complex with mandelic acid. The electrode reaction of Mo(VI)‐mandelic acid system undergoes as one‐electron reduction, exhibiting properties of a surface electrode process. In the presence of chlorate, bromate, and hydrogen peroxide, the electrode reaction is transposed into a catalytic mechanism. The experimental results are compared with the recent theory for surface catalytic reaction, enabling qualitative characterization of the electrode mechanism in the presence of different catalytic agents. Utilizing both the method of “split SW peaks” and “quasireversible maximum” the standard redox rate constant of Mo(VI)‐mandelic acid system was estimates as ks=150±5 s−1. By fitting the experimental and theoretical results, the following catalytic rate constants have been estimated: (8.0±0.5)×104 mol−1 dm3 s−1, (1.0±0.1)×105 mol−1 dm3 s−1, and (3.2±0.1)×106 mol−1 dm3 s−1, for hydrogen peroxide, chlorate, and bromate, respectively.