Chromium-titanium-antimony oxide composite anodes: Electro-organic oxidations

Beck, F.; Schulz, H.

doi:10.1007/bf01024357

Cited by 17 publications

(1 citation statement)

References 25 publications

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“…A number of oxide systems other than the ruthenium system have been postulated to mediate the oxidation of organic compounds. For example, Beck and Schulz (34)(35)(36) have demonstrated that chromium oxide-based anodes are active for oxidation of a number of organic compounds, especially isopropanol. A cyclic redox oxidation mechanism, involving the Cr(VI)/Cr(III) couple, is thought to mediate the oxidation process at these anodes.…”

Section: Discussionmentioning

confidence: 99%

Electro‐Oxidation of Formaldehyde on Thermally Prepared RuO2 and Other Noble Metal Oxides

O’Sullivan

White

1989

J. Electrochem. Soc.

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The electro-oxidation of formaldehyde has been investigated at thermally prepared noble metal oxides, especially RuO2, in aqueous solution. Studies were carried out on thin layers of oxide supported on Ta or Ti, and on thin, Teflonbonded oxide layers attached to a glassy carbon rotating disk electrode. The catalytic activity of RuO2 for HCHO oxidation was considerably greater than that of IrO2 and Rh203. At RuO2, formaldehyde was observed to undergo oxidation to formate at potentials from ca. 0.75-1.25V vs. reference hydrogen electrode (RHE), and to carbonate at higher potentials. The results suggest that HCHO (and HCOOH) oxidation is mediated by higher valent states 'of the oxide metal ions electrogenerated at the electrode surface. Values of I0 -3 cm s -1 (geometric electrode area based) and 10 -6 cm s -1 (real area based) were estimated for the heterogeneous rate constant for HCHO oxidation at RuO,.. The activity for HCHO oxidation is correlated with the catalytic activity of the oxides for the oxygen gas evolution reaction.Formaldehyde is an important reducing agent used in electroless metal deposition, where an electrochemical type mechanism involving anodic oxidation of the HCHO along with cathodic reduction of the metal ion is considered to be involved (1, 2). Further, formaldehyde belongs to the group of C1 compounds, which also includes methanol and formic acid, which is the subject of considerable attention in electrochemical energy conversion research (3). The electro-oxidation of formaldehyde has been the subject of a number of investigations at metallic electrodes (4-6). In alkaline solution, formate has been generally found to be the product of HCHO oxidation, and the evolution of H2 gas derived from the HCHO may also be observed during the oxidation reaction depending on the nature of the catalyst and the experimental conditions (4, 7). In a number of instances it has been observed that metals which are catalytically active for HCHO oxidation exhibit significantly less activity when anodic oxides are formed on their surfaces, e.g., Au (8). On the other hand, the oxidation of certain organic molecules, including HCHO, at Ni is observed only in the presence of an anodic oxide layer in which the Ni species are oxidized beyond the Ni(II) state (9, 10). This suggests that certain metal oxides should exhibit catalytic activity for the electro-oxidation of HCHO.The class of noble metal oxides merits attention as potential electrocatalysts for organic oxidation reactions in view of the high catalytic activity possessed by certain members of this class, e.g., RuQ, for the C12 and 02 generation reactions (11,12). Benzaldehyde has been shown to undergo electro-oxidation at RuO2 (13). There appear to be no reports in the literature of studies of HCHO oxidation at oxide electrodes. In this paper, a study of HCHO oxidation at a number of thermally prepared noble metal oxides, principally RuQ, is described. ExperimentalSome of the oxide electrodes used in this work were prepared essentially according to the stand...

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Section: Discussionmentioning

confidence: 99%

Electro‐Oxidation of Formaldehyde on Thermally Prepared RuO2 and Other Noble Metal Oxides

O’Sullivan

White

1989

J. Electrochem. Soc.

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Basic characteristics of spinel type manganese mixed oxide/titanium composite anodes for electroorganic redox catalysis

Lodowicks

Beck

1994

Chem Eng & Technol

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Manganese mixed oxide composite layers of about 1 pm thickness on titanium sheet as substrate were fabricated by firing of the corresponding nitrates at a typical temperature of 400°C in air. The activity of these anodes was evaluated by cyclic voltammetry (10 mV/s) and the stability was determined by chronopotentiometry (2.5 mA/cm2) in 1M H2S04. The oxidation of 2-propanol was examined as a simple electroorganic model reaction. The quality of a first category of mixed oxides with general composition MnMe204 decreased in the order Me = Co, Ni, Fe. In a second group with the general formula MeMn204 a decrease in the order Me = Co, Cu, Fe, Ni, Ti, Zn, Cd, Ca, Mg, (Zn, Ge), Li was observed. The corresponding candidates of the second group were superior to those of the first. The anode service life r of the optimum spinel anode CoMn204/Ti is dependent on the current density, according to j A 7 = const. ( A = 1.7). Thus high current densities are precluded. The mechanism has been discussed in terms of a heterogeneous redox catalysis: surface Mn(VI1) states are formed in a slow electrochemical step. In a subsequent fast chemical oxidation of the organic molecule the original reduced state is regenerated. This also explains the comparatively good service life of these anodes.

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Preparation, Analysis and Behaviors of Ti-Based SnO2 Electrode and the Function of Rare-Earth Doping in Aqueous Wastes Treatment

Feng

Liu²,

Ding³

2009

Electrochemistry for the Environment

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Chromium-titanium-antimony oxide composite anodes: Electro-organic oxidations

Cited by 17 publications

References 25 publications

Electro‐Oxidation of Formaldehyde on Thermally Prepared RuO2 and Other Noble Metal Oxides

Electro‐Oxidation of Formaldehyde on Thermally Prepared RuO2 and Other Noble Metal Oxides

Basic characteristics of spinel type manganese mixed oxide/titanium composite anodes for electroorganic redox catalysis

Preparation, Analysis and Behaviors of Ti-Based SnO2 Electrode and the Function of Rare-Earth Doping in Aqueous Wastes Treatment

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