Ethanol tolerant precious metal free cathode catalyst for alkaline direct ethanol fuel cells

Abstract

La0.7Sr0.3(Fe0.2Co0.8)O3 and La0.7Sr0.3MnO3 −based cathode catalysts are synthesized by the sol-gel method. These perovskite cathode catalysts are tested in half cell configuration and compared to MnO2 as reference material in alkaline direct ethanol fuel cells (ADEFCs). The best performing cathode is tested in single cell setup using a standard carbon supported Pt0.4Ru0.2 based anode. A backside Luggin capillary is used in order to register the anode potential during all measurements. Characteristic processes of the electrodes are investigated using electrochemical impedance spectroscopy. Physical characterizations of the perovskite based cathode catalysts are performed with a scanning electron microscope (SEM) and by X-ray diffraction showing phase pure materials. In half cell setup, La0.7Sr0.3MnO3 shows the highest tolerance toward ethanol with a performance of 614mAcm−2 at 0.65V vs. RHE in 6M KOH and 1M EtOH at RT. This catalyst outperforms the state-of-the-art precious metal-free MnO2 catalyst in presence of ethanol. In fuel cell setup, the peak power density is 27.6mWcm−2 at a cell voltage of 0.345V and a cathode potential of 0.873V vs. RHE.