Electrospun Fuel Cell Electrodes and Their Behavior Under Hydrogen/Air Start-up/Shut-Down Conditions

Abstract

Affordable and clean energy is one of the 17 sustainable development goals proposed by the United Nations in 2015. [1] In this context, polymer electrolyte membrane fuel cells (PEMFCs) are a promising renewable and clean energy conversion technology. The large implementation of PEMFCs, however, is hindered by high loading of very costly and scarce platinum group metals (PGM) and insufficient long-term durability. Most of the cathode catalysts are suffering from hydrogen/air start-up/shut-down (SUSD) conditions. [2, 3] Generally, the performance of the PEMFC is controlled by the utilization of the catalytically active sites and the mass transport properties within the porous catalyst layers (CL) in particular operating at high current density. New strategies in the design of functional porous catalyst layers are needed to overcome these challenges. As a very promising strategy, nanometer-sized fibers prepared by electrospinning can be used as a backbone to improve the utilization and accessibility of catalytically active sites by maintaining the PGM loading. [4, 5]In this work, a nozzle-free electrospinning machine by Elmarco S.R.O. (Liberec, Czech Republic) was employed to design and nano-engineer advanced catalyst layers with improved catalytic as well as mass transport properties. Thereby, several highly homogeneous catalyst layers deposited on gas diffusion layer with controlled platinum loading of up to 0.1 mg/cm2 were prepared and characterized by scanning electron microscope (SEM) and micro X-ray fluorescence spectroscopy (μ-XRF). The structural information such as morphology and chemical distribution was correlated with the electrochemical data obtained from the single cell measurements in a fuel cell test station. Additionally, the durability of the as-prepared nanofiber-based catalyst layers was studied under real hydrogen/air SUSD conditions.Our results show the impact of different nanostructured catalyst layers prepared by electrospinning process on the long-term performance of the PEMFC. Here, we will present the great advantages of the electrospun catalyst layers over the classical catalyst layers prepared by decal transfer process.