Catalytic Adsorptive Stripping Voltammetry of Molybdenum: Redox Kinetic Measurements

Abstract

The 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)

Rapid Determination of Picomolar Titanium in Seawater with Catalytic Cathodic Stripping Voltammetry

“…Previous studies have also shown that the catalytic term is faster for bromate than for chlorate for both Ti 41 and Mo. 42 Initial DP-CSV work showed that a combination of bromate and Cupferron was optimal, as high concentrations of Cupferron increased the blank considerably (see below). The presence of bromate (see Figure 3 and Figure S6 in the Supporting Information) lead to a characteristic positive wave immediately after the reduction wave of the TiO(Cup) 2 complex.…”

“…The presence of bromate (see Figure and Figure S6 in the Supporting Information) lead to a characteristic positive wave immediately after the reduction wave of the TiO(Cup) 2 complex. Such phenomena have also been observed in the catalytic adsorptive stripping of Mo . This change in peak shape was also responsible for an anodic shift in E p with the addition of bromate (Figure S7 in the Supporting Information), although further additions of bromate resulted in an increasingly cathodic shift, as also seen for bromate and Ti(EDTA) .…”

“…Using this approach, it was found that the catalytic rate constants were in the following order: Cupferron > bromate > chlorate. Previous studies have also shown that the catalytic term is faster for bromate than for chlorate for both Ti and Mo …”

Design and Construction of a New Modified Screen‐Printed Sensor for Voltammetric Determination of Molybdenum(VI) Ions

“…The presence of chlorate enhanced the reduction current which was attributed to the catalytic reduction of Mo(V) by chlorate. Chlorate as oxidizing agent convert probable Mo(IV) to Mo(V), whilst chlorate reduces to a metastable reduction product Cl(IV) 37–40. This implies that the catalytic effect of chlorate enhances the sensitivity of the Cup‐SPCE toward Mo(VI).…”

Electrocatalysis of the first and second kind: Theoretical and experimental study in conditions of square-wave voltammetry

“…Catalytic electrode reactions are the focus of voltammetric analysis, as they provide a means for developing highly sensitive procedures for quantitative determination [1][2][3][4][5][6][7][8][9][10]. The simplest catalytic mechanism is an EC reaction scheme, where E refers to the electrode reaction and C is a follow-up irreversible chemical step with a first order kinetics, through which the electroactive reactant is regenerated.…”