Electron-Conductive Three-Dimensional Inorganic Nanocrystals As a New Catalyst Support for PEM Fuel Cell Cathode

Abstract

State-of-the-art polymer electrolyte membrane fuel cells (PEMFC) cathode catalysts are platinum or platinum alloy nanoparticles loaded on a high surface area carbon support. Although these catalysts have been successfully implemented in passenger fuel-cell electric vehicles (FCEVs) (e.g., the Toyota Mirai), these catalysts are facing many performance and durability challenges that limit their applications in medium-duty and heavy-duty transportation. Among these challenges is the corrosion of the carbon support, which represents a source of efficiency loss (i.e., maximum voltages must be “clipped” to prevent catalyst degradation) and limitation of PEMFC lifetime. Corrosion of the carbon support affects catalyst utilization and the transport properties of the cathode as it can result in loss of electrical connection to the platinum alloy nanoparticles and destruction of electrode porosity.1-4 This talk introduces a new class of PEM fuel cell cathode catalyst supports called electron-conductive three-dimensional inorganic nanocrystals. The highly-conductive nanocrystals are fabricated by a chemical vapor deposition (CVD) assisted route using a home-built vertical plug-flow fused-quartz reactor. The developed synthesis method can produce gram scale amounts and operates in batch mode. Platinum nanoparticles have been introduced to the surface of newly- developed supports using different synthetic routes in order to demonstrate the excellent support durability after being subjected to different synthetic treatments. The ORR activity, catalyst performance durability, and catalyst support durability have been evaluated by means of the thin-film rotating disk electrode (TF-RDE) technique. The platinum content in the prepared catalysts has been measured using inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF). The morphology, crystal structure, and spatial distribution of the metal nanoparticles have been characterized by scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS), respectively. The electronic structure of the conductive 3-D inorganic nanocrystals has been identified by means of electron energy-loss spectroscopy (EELS), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) to be graphene-like with sp2 hybridized bonds.AcknowledgementsThis work was supported by the United States Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office. Argonne is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357 by UChicago Argonne, LLC.References F. Cetinbas, R. K. Ahluwalia, N. N. Kariuki, and D.J. Myers, J. Electrochem. Soc., 165(13), F1051 (2018).Kongkanand and M. F. Mathias, J. Phys. Chem. Lett., 7, 1127 (2016).Subbaraman, D. Strmcnik, A. P. Paulikas, V. R. Stamenkovic, and N. M. Markovic, Chemphyschem, 11, 2825 (2010).Cullen, David A., K. C. Neyerlin, Rajesh K. Ahluwalia, Rangachary Mukundan, Karren L. More, Rodney L. Borup, Adam Z. Weber, Deborah J. Myers, and Ahmet Kusoglu. "New roads and challenges for fuel cells in heavy-duty transportation." Nature Energy (2021): 1-13.