Microwave-electrochemical formation of colloidal zinc oxide at fluorine doped tin oxide electrodes
ABSTRACT Colloidal ZnO is obtained during microwave-enhanced electrochemical deposition experiments from an aqueous solution containing 0.1 M Zn(NO3)2 and 0.02 M H2O2 via repetitive negative going potential cycles from 0.3 to −0.8 V vs. SCE. The effects of temperature and temperature gradients on ZnO electro-formation at fluorine doped tin oxide (FTO) electrodes are investigated with both a conventional thermostated bath system (isothermal) and an in situ microwave electrochemistry system (non-isothermal). Mainly electrodeposition of ZnO is observed in uniformly heated stagnant solution and predominantly the electro-formation of ZnO colloid is observed in the presence of microwave-induced temperature gradients in a flowing solution. For the ZnO colloid prepared via microwave activation, SAXS data suggests an average particle radius of ca. 18 nm. The increase of ZnO nanoparticle concentration during repetitive potential scans is followed by photoluminescence spectroscopy. A possible mechanism for ZnO colloid formation during electrochemical reduction of H2O2 is suggested.
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ABSTRACT: This article comprehensively reviews a selected subfield of thermoelectrochemistry, which bases upon joule-heated working electrodes. Both directly and indirectly heated electrodes are considered. In all cases, an electric current (AC or DC) is used to elevate the electrode temperature during the electrochemical processes. The development of joule-heated electrodes started as early as 1966 and was greatly accelerated by Gründler et al. since 1993. However, during the last 5 years the development became even faster, when other groups started to contribute novel approaches and designs on how to implement electrically heated electrodes in capillary electrophoreses and spectroelectrochemistry. To date there are more than 90 publications on heated electrodes.Electroanalysis 01/2012; 24(1):23. · 2.82 Impact Factor