Development and characterization of direct formic acid fuel cell for potable power applications

In this paper, novel Pd catalysts show unusually high catalyst activity of oxidizing formic acid for direct formic acid fuel cell (DFAFC). Pd appears to oxidize formic acid primarily through a direct, non-CO-forming pathway and it does not tend to poison by CO. For active DFAFC, high surface area Pd black catalysts produce both high open cell potential of 0.9 V and high current density output of 600 mA/cm2 at 0.4 V. Low surface area Pd black catalysts show a rapid deactivation and a much lower activity than high surface area Pd black catalysts, possibly due to a particle size effect.; Passive air breathing DFAFCs using Pd-based catalysts also generate high performances. However, the performance of the passive cell was much lower than its active cell because of the oxygen transport limitation to the cathode electrode in the air breathing structure of the passive cell.; Furthermore, Magnetic Resonance Imaging (MRI) is used to determine the spatial distributions of water and fuel in the membrane and GDL's of operating DFAFC. MRI images taken with a 14.7 T imaging system, show that the fuel distribution with the operating fuel cell is non-uniform. Generally, there is more fuel in the bottom of the cell, while the upper part of the flowfield is partially filled with CO2. Water distribution also shows non-uniformities. The areas of the GDL under the ribs in the flowfield are generally flooded, and there are other flooded spots that grow and shrink as performance changes.