Attenuated degradation of a PEMFC cathode during fuel starvation by using carbon-supported IrO_2

摘要

IrO_2, a water electrolysis catalyst, has been known to be effective in preventing corrosion of the carbon support in proton exchange membrane fuel cells (PEMFCs). Particulate IrO_2 can agglomerate easily, which can decrease substantially the catalytic surface area required for oxygen evolution reaction, causing the loss of catalytic efficiency. Furthermore, agglomerated IrO_2 nanoparticles can have an adverse effect on the oxygen reduction reaction by covering the active surface area of the Pt/C cathode catalyst, which is a damaging factor for the intrinsic performance of PEMFC. Carbon-supported iridium oxide, IrO_2/C, which can prevent the agglomeration of Ir nanoparticles more effectively, was synthesized to overcome these problems. Compared to the cell with the Pt/C cathode only, the cell with 10 wt.% IrO_2 particles and Pt/C cathode showed stronger durability during fuel starvation but the cell performance at normal operation decreased severely by 35%. The cell with the same amount of IrO_2 dispersed on a carbon support, 10 wt.% IrO_2/C, showed similar durability during fuel starvation maintaining the cell performance comparable to the cell using a Pt/C cathode only. Carbon-supported IrO_2, IrO_2/C, was more effective than IrO_2 particles in both maintaining the intrinsic performance and improving the cell durability during fuel starvation.