Oxidation of nitric oxide (NO) for subsequent efficient reduction in selective catalytic reduction or lean NO(x) trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used platinum (Pt)-based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn(2)O(5) are an efficient substitute for the current commercial Pt-based catalysts. Under laboratory-simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability, and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120°C with conversion maxima of ~45% higher than that achieved with Pt. Density functional theory and diffuse reflectance infrared Fourier transform spectroscopy provide insights into the NO-to-NO(2) reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.

A platinum group metal-free (PGM-free) oxygen reduction reaction (ORR) catalyst engineered for stability has been synthesized using the sacrificial support method (SSM). This catalyst was comprehensively characterized by physiochemical analyses and tested for performance and durability in fuel cell membrane electrode assemblies (MEAs). This catalyst, belonging to the family of Fe-N-C materials, is easily scalable and can be manufactured in batches up to 200 g. The fuel cell durability tests were performed in a single cell configuration at realistic operating conditions of 0.65 V, 1.25 atm gauge air, and 90% RH for 100 hours. In-depth characterization of surface chemistry and morphology of the catalyst layer before and after durability tests were performed. The failure modes of the PGM-free electrodes were derived from structure-to-property correlations. It is

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Mass transport properties of a pair of non-Platinum Group Metal (non-PGM) catalysts in proton exchange membrane fuel cells (PEMFCs) were evaluated through methods developed by Reshetenko et al., demonstrating that the use of different carrier gases can allow for the determination of the mass transport coefficient for oxygen in the gas phase and the electrolyte phase. The gas-phase and non-gas-phase resistances can be elucidated from the slope and intercept, respectively, of the total mass transport coefficient plotted as a function of molecular weight. It was determined through these experiments that the primary sources of mass transfer limitations of the non-PGMs when compared to the PGMs were the catalyst layer (non-gas-phase), rather than the flow fields (gas-phase, primarily Knudsen Diffusion effects), and the gas diffusion layer. This work was combined with a pseudo-2D, isothermal, steady state numerical model to estimate the gas-phase mass transfer coefficient and the fraction of hydrophobic, gas-phase pores in the catalyst layer. Sensitivity studies were also carried out, allowing for more information regarding the influence of several inherent factors on the mass transport limitations, and allow for additional validation of the model beyond simply the quality of the fit.

The cost‐effectiveness and excellent performance of conductive‐carbon‐supported Ni‐based electrocatalysts make them attractive materials for hydrogen oxidation and evolution reactions. However, they were previously unused in gas‐phase hydrogenation reactions. In this work, we have expanded the applicability of commercially available advanced Ni/C, NiMo/C and NiRe/C materials from electrocatalysis to heterogeneous catalysis of CO2 methanation. Our catalytic testing efforts indicate that the monometallic Ni/C material demonstrates the best CO2 methanation properties, achieving an excellent CO2 conversion of 83 % at 400 °C with nearly complete selectivity to CH4 of 99.7 %, plus exhibiting intact performance during 90 h of time‐on‐stream testing. Such catalytic properties are among the highest reported to date among carbon‐supported Ni‐based methanation catalysts. Excellent performance of Ni/C stems from the good dispersion of the Ni nanoparticles over N‐containing carbon support material.

There are an increasing number of published works devoted to development of Platinum Group Metal-free (PGM-free) electrocatalysts for both the anode [1] and cathode [2] sides of membrane electrode assembly (MEA). Several laboratory scale methods were used for preparation of cathodic electrocatalysts based on pyrolysis of chelate compounds [3], Metal-Organic Frameworks (MOFs) [4], graphene-like derivatives [5] and small organic molecules [6]. Other classes of electrocatalysts for fuel cells (FCs) and electrolyzers (ECs) application based on PGM supported or in a black form were comprehensively studied by many research groups [7]. With a significant progress in improving stability, activity and durability of FC and EC catalysts the need in universal, scalable and reproducible manufacturing approach was arisen. Pajarito Powder (PP) developed such an approach trademarked as a VariPore™ method (Figure 1). Figure 1. Schematics of VariPore™ manufacturing method The method is based on licensed intellectual property (IP) from several academic institutions, internal Pajarito’s know-hows and PP’s proprietary innovations. It can be described as synthetic approach utilized different pore and particle formers (hard and soft templating) in order to control morphology (pore size distribution, particle size distribution, surface area), chemical composition (surface and bulk chemistry) and physical properties (electrical and thermal conductivity, density and other). At different stages of method development, it was successfully applied for the preparation at scale: PGM-free ORR electrocatalysts [8,9], unsupported PGM electrocatalysts [10], Engineered Catalysts Supports (ECSs, publication is in preparation) and materials for Anion Exchange Membrane (AEM) fuel cells and electrolyzers [11, 12]. The general approach of VariPore™ is based on infusion of pore and particle formers (silica, magnesia and other templates) with precursors of final materials (PGM salts, base metals salts, organic compounds and other) followed by chemical transformation of these precursors into the supports or catalysts. Soft chemical reduction (formic acid), strong chemical reduction (hydrazine) and high temperature treatment (inert, reducing or reactive) were successfully optimized in order to produce mentioned above classes of materials for FC and EC applications. This presentation will describe the application of VariPore™ for the preparation of ECS materials, PGM-free catalysts for PEM and AEM fuel cells, CO2 electroreduction (CO2ER), Direct Methanol Fuel Cells (DMFC) and novel classes of electrocatalysts for AEM electrolyzers. Acknowledgement: This work was supported by US DOE EERE grant DE-EE0008419 "Active and Durable PGM-free Cathodic Electrocatalysts for Fuel Cell Application" PI: Alexey Serov. References [1] Serov, C. Kwak Applied Catalysis B: Environmental 90 (2009) 313–320. [2] T. Thompson, A. R. Wilson, P. Zelenay, D. J. Myers, K. L. More, K.C. Neyerlin, and D. Papageorgopoulos ElectroCat: DOE's approach to PGM-free catalyst and electrode R&D. Solid State Ionics, 319: 68-76, 2018. doi:10.1016/j.ssi.2018.01.030. [3] A. Serov, M. Min, G. Chai, S. Han, S. J. Seo, Y. Park, H. Kim, C. Kwak J. Appl. Electrochem. 39 (2009) 1509–1516. [4] Pavlicek, S. C. Barton, N. Leonard, H. Romero, S. McKinney, G. McCool, A. Serov, D. Abbott, P. Atanassov, S. Mukerjee J. Electrochem. Soc. 165 (2018) F589-F596. [5] Santoro, M. Kodali, S. Kabir, F. Soavi, A. Serov, Plamen Atanassov J. Power Sources 356 (2017) 371–380. [6] Chen, R. Gokhale, A. Serov, K. Artyushkova, P. Atanassov Nano Energy 38 (2017) 201-209. [7] Kabir, A. Serov "Anodic materials for electrooxidation of alcohols in alkaline media" Electrochemistry: Volume 14, edited by Craig Banks, Steven McIntosh, RSC 2017. [8] Serov, M. J. Workman, K. Artyushkova, P. Atanassov, G. McCool, S. McKinney, H. Romero, B. Halevi, T. Stephenson J. Power Sources 327 (2016) 557-564. [9] Stariha, K. Artyushkova, M. J. Workman, A. Serov, S. McKinney, B. Halevi, P. Atanassov J. Power Sources 326 (2016) 43–49. [10] Asset, A. Serov, M. Padilla, A. J. Roy, I. Matanovic, M. Chatenet, F. Maillard, P. Atanassov Electrocatalysis 9 (2018) 480–485. [11] Serov, N. I. Andersen, A. J. Roy, I. Matanovic, K. Artyushkova, P. Atanassov J. of The Electrochem. Soc. 162 (4) (2015) F449-F454. [12] Roy, M. R. Talarposhti, S. Normile, I. V. Zenyuk, V. de Andrade, K. Artyushkova, A. Serov, P. Atanassov Sustainable Energy Fuels 2 (10) (2018) 2268-2275. Figure 1

The unprecedented situation with global COVID-19 pandemic exposed a significant vulnerability of world economics related to rearrangement and in some cases disappearance of supply chains. The Platinum Group Metals (PGMs) are listed critical minerals in practically all developed countries including USA, EU, UK and others. To ensure uninterrupted development of clean energy technologies, such as fuel cells and electrolysis, which are heavily depend on PGMs a significant breakthrough should be made to switch to completely PGM-free materials. Pajarito Powder in a close collaboration with world leader in MEA manufacturing IRD Fuel Cells, Hawaii Natural Energy Institute, University of Hawaii, and a number of US DOE National Labs (ANL, ORNL, LANL, NREL and other) developed under US DOE ElectroCat project Fe-N-C PGM-free catalysts for the Oxygen Reduction Reaction which are ready for commercial evaluation in some fuel cells applications [1-7]. The main focus of the project was not only to synthesize ORR catalysts with the highest activity and durability, but also in the way which can be easily scaled up to the hundreds of metric tons of catalysts. Pajarito Powder used the VariPore™ method for manufacturing several sets of PGM-free catalysts (with more than 30 synthesized at the time of abstract submission) with variation of surface area, level of graphitization, particle and pore size distribution, bulk and surface chemical composition as well as hydrophobic properties. These materials were synthesized by a bottom-up approach using nitrogen-rich organic compounds, transition metal salts, and particle/pore formers (either one or series of them). Pajarito’s method include aggressive catalyst cleaning where unreacted metal nanoparticles, remaining particle/pore formers, and admixtures from acids are removed. The resulting materials are active towards ORR sites and predominantly consists of atomically dispersed Fe-Nx moieties [1-4]. Pajarito’s unique capability to prepare these materials reproducibly at a 50+ grams per batch level allowed IRD Fuel Cells to produce industrial quality MEAs with reproducible performance (~300 MEAs with 25cm2 active area are made at the time of abstract submission). This oral presentation will report results of physical-chemical characterization of PGM-free catalysts, their comprehensive analysis at HNEI, modeling done by Dr. Andrei Kulikovsky, and structure-to-properties correlations obtained by our Team in collaboration with ElectroCat consortium. The critical challenges and path to overcome them will be discussed [1-3]. Acknowledgments: We would like to acknowledge the financial support from US DOE EERE under the grant DE-EE0008419 “Active and Durable PGM-free Cathodic Electrocatalysts for Fuel Cell Application” (PI: Alexey Serov). References: [1] T. Reshetenko, G. Randolf, M. Odgaard, B. Zulevi, A. Serov, A. Kulikovsky "The Effect of Proton Conductivity of Fe–N–C–Based Cathode on PEM Fuel cell Performance" Journal of The Electrochemical Society 167 (2020) 084501. [2] A. Baricci, A. Bisello, A. Serov, M. Odgaard, P. Atanassov, A. Casalegno "Analysis of the effect of catalyst layer thickness on the performance and durability of platinum group metal-free catalysts for polymer electrolyte membrane fuel cells" Sustainable Energy Fuels 3 (12) (2019) 3375-3386. [3] C.L. Vecchio, A. Serov, H. Romero, A. Lubers, B. Zulevi, A.S. Aricò, V. Baglio "Commercial platinum group metal-free cathodic electrocatalysts for highly performed direct methanol fuel cell applications" J. of Power Sources 437 (2019) 226948. [4] S. Stariha, K. Artyushkova, M. J. Workman, A. Serov, S. McKinney, B. Halevi, P. Atanassov "PGM-free Fe-N-C catalysts for oxygen reduction reaction: Catalyst layer design" J. Power Sources 326 (2016) 43–49. [5] S. Rojas-Carbonell, K. Artyushkova, A. Serov, C. Santoro, I. Matanovic, P. Atanassov "Effect of pH on the activity of platinum group metal-free catalysts in oxygen reduction reaction" ACS Catalysis 8 (2018) 3041-3053. [6] M.J. Workman, A. Serov, L. Tsui, P. Atanassov, K. Artyushkova "Fe-N-C Catalyst Graphitic Layer Structure and Fuel Cell Performance" ACS Energy Lett. 2 (2017) 1489–1493. [7] M. J. Workman, M. Dzara, C. Ngo, S. Pylypenko, A. Serov, S. McKinney, J. Gordon, P. Atanassov, K. Artyushkova "Platinum group metal-free electrocatalysts: Effects of synthesis on structure and performance in proton-exchange membrane fuel cell cathodes" J. Power Sources 348 (2017) 30-39.