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.