Membrane degradation behavior during open-circuit voltage hold test

The correlation between the degradation behavior of a membrane electrode assembly (MEA) and deposited Pt (Pt band) in the membrane during an open-circuit voltage hold test was studied. The degradation behavior was investigated by measuring the fluoride ion emission in the effluent water from the anode and the cathode for various gas compositions at both electrodes. The results showed that the fluoride ion emission rate (FER) varied in accordance with the gas compositions. Cross sections of the tested MEAs were observed using a transmission electron microscope. It was found that the location of the Pt band correlated with the magnitude of the FERs. The Pt band was located close to where the mixed potential in the membrane, which was determined by the gas compositions, changed dramatically. (c) 2007 The Electrochemical Society.