Alkaline Microfluidic Hydrogen-Oxygen Fuel Cell as a Cathode Characterization Platform

We report on an alkaline microfluidic fuel cell for catalyst and electrode characterization. Its constantly refreshing alkaline electrolyte stream enables autonomous control over the flow rate and electrolyte composition, as well as independent analysis of the individual electrodes, rendering this platform a powerful analytical tool. Here, polytetrafluoroethylene (PTFE)-bonded Ag/C and Pt/C cathodes are investigated and optimized using several characterization techniques, including chronoamperometry and electrochemical impedance spectroscopy. A loading of 40 wt % PTFE and hot pressing of the electrodes were found to lead to the best performance. Moreover, improvements in cell performance as a function of increasing [KOH] were investigated and the dual effects of enhanced oxygen reduction reaction activity and improved ionic conductivity were decoupled. Peak power densities as high as 110 mW/cm(2) were obtained, suggesting that the current alkaline fuel cell configuration may also hold promise as a microscale power source. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3083226] All rights reserved.