Studies on water behavior in the vicinity of a catalyst layer (CL) and its effect on the cell performance are important challenges because water management is a key factor to achieve higher performance of polymer electrolyte fuel cells (PEFCs). In this study, a microdevice that contains a catalyst coated membrane (CCM) was developed (1) and in-operando infrared (IR) microscopy was conducted to visualize water behavior on the CL. Two types of CLs contain either carbon (2) or tin oxide (3) as supporting material to investigate the effects of materials on the water behavior and cell performance.

The microdevice, which was made of a silicon wafer, contains two microchannels (100 μm-width, 200 μm-pitch) and a current-collecting layer (30 μm-width) on a rib of the cathode plate. The CCM was sandwiched by two plates. The anode channel faced the rib of the cathode. The surface of a cathode catalyst layer was coated with thin Au by sputtering to enhance IR reflectance, which did not change the porous structure of the CL significantly. The surface of the cathode catalyst layer was observed by IR microscopy through the cathode plate.

Figure 1 shows liquid water generated during the constant current operation of the device. The catalyst layer contains carbon as the supporting material in this case. The effects of the materials and flow conditions on the water behavior and cell performance were investigated.

Acknowledgments

This work was supported by NEDO ECCEED’30.

References

(1) T. Suzuki et al., J. Therm. Sci. Technol., 11 (2016), 16-00370.

(2) T. Suzuki et al., Int. J. Hydrogen Energy, 41 (2016), 20326.

(3) Y. Chino et al., J. Electrochem. Soc., 162 (2015), F736.