ISSN:
0930-7516
Schlagwort(e):
Chemistry
;
Industrial Chemistry and Chemical Engineering
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
Notizen:
Manganese mixed oxide composite layers of about 1 μm 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 H2SO4. 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 MnMe2O4 decresed in the order Me = Co, Ni, Fe. In a second group with the general formula MeMn2O4 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 τ of the optimum spinel anode CoMn2O4/Ti is dependent on the current density, according to jλ τ = const. (λ = 1.7). Thus high current densities are precluded. The mechanism has been discussed in terms of a heterogeneous redox catalysis: surface Mn(VII) 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.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/ceat.270170508
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