Electrochemical reduction of CO2 on platinum electrodes in acid solutions

Abstract CO2 reacts in acid solutions with chemisorbed hydrogen on platinum in the potential range of Eh = 0–250 mV to form a chemisorption product of reduced CO2 (perhaps CO). The rate of reduction on bright platinum at room temperature is very slow, taking more than 2 min at Eh = 0 for the total formation of a monolayer of reduced CO2. This rate increases greatly with temperature. On platinized platinum at 90°C the hydrogen reacts extremely rapidly in the potential range Eh = 0–250 mV to reduce CO2 The oxidation of the chemisorbed product to CO2 appears as a current peak in the “fast” i(E)- sweep curve (“CO2-peak”). This oxidation is highly irreversible. With bright platinum an activation energy of 22 kcal/g mol has been measured.