engleski

Investigations of chromium doped ceramic rutile electrodes

The chromium content of rutile electrodes prepared using the ceramic method at 1400°C varied from 0.4% to 20%. Some of these electrodes showed n-type conductivity when treated additionally with hydrogen at 900°C. Dopand concentration was shown to influence significantly the bulk (SEM and x-ray analysis) and surface properties (photoelectrochemical investigations) of TiO2 electrodes. The doping of TiO2 with Cr2O3 near the solubility limit (the formation of solid solutions) was established as between 0.4% and 1%. This concentration produces optimum photoresponse and a shift in the flat-band potential toward more negative values. However, a negative effect of doping due to the decreased hole diffusion length was observed The formation of Andersson (Magneli) phases with the general formula Tin−2Cr2O2n−1, where n is more than 5, associated with high levels of chromium content well above the solubility limit, leads to reduced activity of these electrodes when used as photoanodes or preparative anodes in heterogenous redox catalysis. Important factors affecting the properties of these electrodes as preparative anodes in redox catalysis are the process of thermal pretreatment and the atmosphere in which they are heated.

rutile electrode; n-type conductivity; dopand concentration

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