In this work the mechanisms of electrooxidation of Mn 2+ to MnO2 were investigated in perchlorate, sulphate and acetate solutions. Density functional theory (DFT), as a quantum modeling method, was used for identification of red-ox potentials of one-electron oxidation of the aquacomplexes [Mn 2+ (H2O)6], [Mn 2+ (H2O)5(SO4 2-)]. The calculated values were significantly higher than the measured potentials of the initial stages of complexes oxidation on Pt electrode. The thermodynamical possibilities of formation of oxocomplexes and the kinetic measurements were analyzed. Based on this data it has been found that in perchlorate and sulphate solutions (pH 4) Mn 2+-iones were oxidized due to the interaction with adsorbed •OH-radicals, produced by the water-splitting reaction. For strongly acid sulphate solutions (pH 1) it was observed the convergence of values of the potential of water-splitting reaction (1,2 V) and the potential of oxidation of [Mn 2+ (H2O)5(НSO4-)] complex (1,13V). This points to simultaneous implementation of two reaction paths: the direct electrooxidation of Mn 2+-iones and the oxidation due to the interaction with •OH-radicals. The calculated value of potential of electrooxidation of monoacetate aquacomplex of Mn 2+-iones is notably low (0,66 V). This poin to the only electrooxidation path of the reaction. The calculated data have been confirmed by the kinetic measurements. The particles [Mn 3+ (H2O)5(Ас-)] rapidly disproportionate to MnO2 and [Mn 2+ (H2O)5(Ас-)] due to the features of carboxyl group.
Oxidation catalysis of organic substances has attracted special attention in recent years due to of their high industrial significance in green and energy chemistry. The implementation of a transition metal-based catalyst in combination with oxygen is an alternative to the traditional procedures. This study justifies the application of amperometric response 'in situ' for estimation of the electrocatalytic activity of metal oxide films, which are known to be promising for oxygen transfer processes. The reaction of electrooxidation of Mn 2+ ions may be termed as a 'marker' for oxygen transfer reactions due to its kinetic features, such as proportionality between the current density and the surface concentration of •OH-radicals. The relative parameter, k ox , has been offered for estimation of the oxidizing capacity of an anode material toward oxygen transfer reaction in reference to platinum oxidizing capacity. k ox value is automatically calculated exactly during electroplating of MnO x as a ratio of the current density of Mn 2+ + 2H 2 O-2e→MnO 2 +4H + reaction on the tested surface to the current density of this reaction on Pt surface. The developed method was tested during the investigation of catalytic activity of MnO x films for electrooxidation of glucose. The parameter k ox was calculated for other anode materials and was analyzed. The application of the new method allows estimating and comparing the catalytic performance toward oxygen transfer reactions of anode materials or of the same material in different modifications, such as nano particles, composites, different compositions etc. The pre-test reduces manifold the time spent for determination of oxidizing capacity of oxides.
Quantitative composition of organometallic electrodeposit obtained from the solution of 0.1 M CuSO4, 1.0 M H2SO4 and 0.2 M acrylic acid was determined by differential photometry. It was shown that the deposit contains copper complexes in an amount of 15% (wt.). Using the dispersion grain-size and microscopic analysis it was ascertained that the micropowder obtained by mechanical grinding of organometallic electrodeposit is more fine-grained and homogeneous compared with industrial or chemically obtained (by cementation with zinc) copper powders. Microbiological studies using clinical strain of microorganisms Staphylococcus aureus showed that the obtained copper-acrylate micropowder has bacteriostatic and bactericidal action. Suppression of bacteria's vital activity in the interaction with the organometallic dispersion occurs from the first minute of exposure in contrast to the influence of industrial and chemically produced copper powders. This effect is related to the special structure of copper-acrylate powder.
On the basis of quantum-chemical cluster calculations [Ni z+(H 2 O) n L](H 2 O) 5-n in the interval z = +2, +1, 0 and n = 0, 1-5 the mechanism of electroreduction of complexes of Ni 2+ and acrylic acid (HAk) has been proved. It has been demonstrated that the initial reactant is the [Ni 2+ (H 2 O) 5 Ak-], the intermediate is the [Ni + (H 2 O) 2 Ak-] and the end product exists in various forms among which the most stable is [Ni 0 (H 2 O) 2 (π-HАk)].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.