Electrocatalytic Activities of Perovskite toward Oxygen Reduction Reaction in Concentrated Alkaline Electrolytes

Perovskite La0.6Ca0.4CoO3 powder was prepared through a sol-gel method and characterized by XRD and BET. The electrocatalytic properties of La0.6Ca0.4CoO3 (LCCO) and La0.6Ca0.4CoO3-Carbon composite (LCCO-C) based electrode layers towards oxygen reduction reaction (ORR) were studied using rotating ring-disk electrode technique (RRDE) in 1, 4, and 6 M KOH electrolytes. Koutechy-Levich theory and RRDE measurement were applied to acquire the overall electron transfer number and kinetic parameters,such as the kinetic currents and rate constants. The overall electron transfer number was measured to be almost 4 for both pure LCCO and composite LCCO-C. A synergetic effect toward the ORR was observed in the LCCO electrode layer in the presence of carbon. This synergetic effect might be one of the reasons for the improved ORR performance on the composite LCCO-C electrode.Une poudre du p\ue9rovskite La0,6Ca0,4CoO3 a \ue9t\ue9 pr\ue9par\ue9e par la m\ue9thode sol-gel et a \ue9t\ue9 caract\ue9ris\ue9e par diffraction des rayons X et la m\ue9thode BET. Les propri\ue9t\ue9s \ue9lectrocatalytiques des couches d\u2019\ue9lectrode \ue0 base de La0,6Ca0,4CoO3 (LCCO) et du composite La0,6Ca0,4CoO3-carbone (LCCO-C) pour la r\ue9action de r\ue9duction d\u2019oxyg\ue8ne (RRO) ont \ue9t\ue9 examin\ue9es \ue0 l\u2019aide de la technique de l\u2019\ue9lectrode \ue0 disque-anneau tournant (rotating ring-disk electrode ou RRDE) dans des \ue9lectrolytes KOH de 1, 4 et 6 M. L\u2019application de la th\ue9orie de Koutechy-Levich et de la technique RRDE a permis de mesurer le nombre total d\u2019\ue9lectrons transf\ue9r\ue9s et des param\ue8tres cin\ue9tiques comme les courants et les constantes cin\ue9tiques. Le nombre total d\u2019\ue9lectrons transf\ue9r\ue9s atteint pr\ue8s de 4 pour le LCCO pur et le composite LCCO-C. Un effet synerg\ue9tique de la RRO a \ue9t\ue9 observ\ue9 dans la couche d\u2019\ue9lectrode LCCO en pr\ue9sence de carbone. Cet effet synerg\ue9tique pourrait \ueatre l\u2019une des raisons expliquant l\u2019am\ue9lioration du rendement de la RRO sur l\u2019\ue9lectrode composite LCCO-C.Peer reviewed: YesNRC publication: Ye