Investigation of Ionomer/Catalyst Interfacial Degradation in PEMFC Using Pt Nanoparticle Array Electrode

Abstract

Interface between catalyst and ionomer in the catalyst layer of polymer electrolyte membrane fuel cells (PEMFCs) has been a subject of keen interest, but its effect to the durability has not been fully understood due to the complexity of catalyst layer structure. Herein, we suggest Pt nanoparticle (NP) array electrode fabricated using block copolymers as a platform for a focused investigation of Nafion/Pt interface. The interfacial evolution between Pt NP and Nafion thin layer during holding with various fixed potentials were investigated using the Nafion thin layer-coated Pt NP array electrode. A set of analysis for the electrodes with various fixed potentials reveals that the Nafion thin layer becomes densely packed and the interaction between the end group of Nafion side chain and Pt surface is facilitated at the intermediate operating potential (0.4~0.7 V). The rearrangement leads to an increase of oxygen transport resistance, negatively impacting the power performance of PEMFC. The Pt NP array electrode provides a versatile tool to analyze Nafion/Pt interface and fresh insight on the degradation mechanism of PEMFC.