Physicochemical Properties of ECS Supports and Pt/ECS Catalysts

As polymer electrolyte membrane fuel cell technologies see increased use in the transportation and energy sectors, there continues to be a need to produce tunable, high-performance oxygen reduction reaction (ORR) catalysts. This work represents the first detailed investigation of commercially available mesoporous nitrogen-functionalized carbon supports with tunable properties (Engineered Carbon Supports, ECS) and ORR catalysts based on platinum nanoparticles (Pt-NPs) supported on these ECS materials produced by Pajarito Powders, LLC. The ECS materials with tunable concentrations of oxygen and nitrogen functional groups and varied carbon graphitization levels were investigated. First, the physicochemical properties of these Pt/ECS catalysts are presented, alongside their bare, Pt-free ECS analogue carbon support materials as investigated through a combination of characterization techniques. This yields a comprehensive catalog of physicochemical properties, including surface area, the concentration of surface dopants (nitrogen and oxygen), evaluation of graphitic content, morphology, and Pt-NP particle size distribution. Then, the ORR performance of the three different Pt/ECS catalysts in membrane electrode assemblies (MEAs) tested under low-relative-humidity conditions is presented as an example of the performance that can be obtained with these materials. All catalysts demonstrated very promising ORR performance at low relative humidity, achieving current densities between 1.8 and 1.3 A/cm2 at 0.6 V. This work demonstrates that carbon supports with engineered morphologies and compositions achieved through the VariPore synthetic technology developed by Pajarito Powders, LLC are a promising platform to produce supports and catalysts with tunable properties for a variety of applications.