Pt Active Site Density Optimization of the Catalyst Layer for an Ultralow-Pt-Loading PEMFC

Abstract

As a power generation device with high efficiency and low pollution, the proton exchange membrane fuel cell (PEMFC) has the potential to become important energy conversion equipment. Drastically reducing the Pt usage in the catalyst layer (CL) can bring great cost benefits to the PEMFC, whereas it leads to polarization loss caused by the local transport process with the limitation of a reduced Pt loading. Herein, local oxygen transport loss was mitigated by reducing the catalyst mass fraction to adjust the Pt active site density in the CL. A membrane electrode assembly (MEA) with a drastically reduced Pt loading of 0.05 mg Pt cm −2 was synthesized, achieving a maximum mass power density of 12.8 W mg Pt −1. Ultralow-Pt MEAs with CL thickness in proportional variation were prepared to precisely control the cathode Pt active site density. It was found that a cathode CL with moderate Pt active site density is conducive to oxygen transport resistance reduction and performance display. This study lays the foundation for designing and utilizing ultralow-Pt MEA for PEMFC applications.