Atomic layer deposited Pt/Cu bimetallic catalysts for use in high-performance fuel cell cathodes

Abstract

In this study, the performance and durability of a Pt/Cu bimetallic catalyst membrane electrode assembly (MEA) for use in polymer electrolyte membrane fuel cells (PEMFCs)-fabricated via plasma-enhanced atomic layer deposition and sputtering-were investigated. The high production costs of Pt-based catalysts limit the commercialization of PEMFCs. Therefore, research to dramatically reduce the loadings of noble metal catalysts, such as Pt, has steadily progressed. Atomic layer deposition may considerably reduce the amount of supported catalyst by precisely controlling the composition and thickness of the catalyst via a self-limiting reaction. According to D-band theory, the Cu catalyst of the Pt/Cu MEA weakened the bonds between the Pt catalyst and oxygen species and improved the oxygen reduction reaction compared to those of the existing Pt MEA. The performance and electrochemical surface area (ECSA) of the Pt/Cu MEA were determined using I-V measurements and cyclic voltammetry, and the durability of the Pt/Cu MEA was analyzed using electrochemical impedance spectroscopy and the accelerated stress test. Thus, when the Pt/Cu MEA was used, the performance and ECSA were improved, and the impedance decreased, compared to those of the Pt MEA.