Improving the Stability of Polymer Electrolyte Membrane Fuel Cells via Atomic Layer-Deposited Cerium Oxide

In this study, to enhance the stability of the cathode platinum (Pt) catalyst in polymer electrolyte membrane fuel cells, cerium oxide (CeOx) was deposited by plasma-enhanced atomic layer deposition (PEALD) process on the Pt catalyst sputtered on the cathode. A change in the peak power density loss after an accelerated stress test (AST) during I-V measurement of the membrane-electrode assembly according to the number of cycles was observed, which confirmed stability improvement. In polymer electrode membrane fuel cells (PEMFCs), free radicals lead to degradation of the performance and stability of catalysts; we used CeOx to prevent these problems. CeOx acts as a free radical scavenger through the redox reaction of Ce3+/4+ ions in the cell test and prevents oxidative hydroxyl and hydroperoxyl radical attack created in the reaction between hydrogen peroxide and released cations. By preventing oxidation, the stability was improved without decreasing the performance. Therefore, the improvement of stability through plasma-enhanced atomic layer deposition CeOx encapsulation can be considered a promising strategy for PEMFC catalysts.