REDUCTION OF CARBON DIOXIDE AT Cu-Zn AND Cu-Sn ALLOYS

S. PETTINICCHI; M.I. SÁNCHEZ DE PINTO; H.BOGGETTI; P.SILVETTI; H. MISHIMA; B.A. LÓPEZ DE MISHIMA

VArsovia

Congreso; 51st Annual Meeting International Society Electrochemistry; 2000

The carbon dioxide is one of the principal responsibles of the global heating of the planet by theeffects that produces its increase in the atmosphere; in consequence the demand for its control andmonitoring the demand has increased. In this work we study the electrochemical reduction of Carbon Dioxide in alkaline medium of Potassium Bicarbonate over carbon paste electrodes modified with Cu-Zn and Cu-Sn metallic alloys. The different catalyst electrodes are Cu-Zn and Cu-Sn metallic alloys, prepared by mechanic alloying in different relation metal proportions. The alloy composition was controlled by SEM-EDAX analysis and the structure was determined using XRD. For the reduction reaction we used a three electrodes cell, the working electrode was a paste carbon electrode modified, the reference electrode was a Saturated Calomel and the counterelectrode a Platinum sheet. The potencial during the reduction was mantained between -0,8 V and -1,2 V. The evaluation of elctrocatalytic activities was determined as functions of the electrolysis potential for various electrodes. We focus on the effects the composition and microcrystalline phases in the Cu-Zn and Cu-Sn alloys on the selectivity, the reversibility and the reactivity of electroreduction of carbon dioxide.The products formulated during the electroreduction, at constant potential, were analyzed by gaschromatography using a flame ionization detector (FID) and a mass detector, taking samples was of different reduction times; the chromatographyc signals would indicated the acetone, methanol and ethanol presence, which would be the possible products formed during the final reduction. The signal intensity is proportional to the quantity of electroreduction products and depends on the type of the catalyst used, the potential and the reduction time.Finally, with the objet of using the Carbón Dioxide reduction electrochemistry reaction in thedevelopment of an electrochemical sensor, we have analysed the different catalysts using current-time curves to constant potential. Among the different catalysts the Cu-Zn alloy seems to be adecuate in the proportion 50:50 because it gives the best response.