抄録
The simultaneous evaluation of the methanol crossover (MCO) and the carbon dioxide crossover (CCO) in a DMFC during operation was conducted with simple measurements of the CO2 and methanol at the cathode and the anode, respectively, in order to derive an equation to estimate the MCO flux and to quantify the magnitude of the CCO flux at the DMFC. The effects of temperature (293-363K), current density (0-400mA/cm2) and the methanol concentration (1, 2 and 3M), as well as the gas/liquid flow rates on the crossover rates were quantitatively studied. With an increase in the current density, the MCO flux linearly decreased, whereas the CCO flux increased to a certain value (about 20% of the MCO flux) and was not affected by it at high current densities. The MCO flux strongly affected by the methanol concentration, temperature and current density, whereas the flow rate of the methanol aqueous solution to the anode and that of the oxygen gas to the cathode weakly affected the MCO in the range measured. From the results, an equation estimate the MCO flux under operation was proposed.
