화학공학소재연구정보센터
Journal of Electroanalytical Chemistry, Vol.478, No.1-2, 108-117, 1999
A comparison of multistability in the electrocatalyzed oxidations of methanol and ethanol in acid and alkaline solutions
Thr non-linear responses of the electrochemical oxidations of methanol and ethanol are studied under constant current conditions. The response of each process in acid solution is compared with the response in NaOH solution. In acid solution, the oxidations of methanol and ethanol exhibit a tristable response in which three different stationary potential values exist under the lame conditions. For ethanol, a different type of tristable response is also exhibited in a small current range and consists of an oscillatory response that coexists with stationary states. A bistable response is obtained for both oxidation processes in NaOH solution. Two types of bistability occur for ethanol oxidation: the coexistence of stationary states and the coexistence of an oscillatory state with a stationary slate. Only stationary states exist in the oxidation of methanol. The results of the current-controlled experiments are explained in terms of known parts of the reaction mechanisms and models describing multistability and anodic oscillations. Simple relations are established between cyclic voltammograms (CVs) and the results of the current-controlled experiments. Although these relations appear obvious, their realization has been elusive in processes involving the oxidation of oxygenated organics. Examples of fundamental oxidation processes are given where these relations do not exist.