DMREF/Collaborative Research: Design and Testing of Nanoalloy Catalysts in 3D Atomic Resolution

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DMREF: Collaborative Research: Design and Testing of Nanoalloy Catalysts in 3D Atomic ResolutionNon-Technical Description: The project aims at the discovery of ultra-small, nanometer-sized alloy catalysts to improve the efficiency of fuel cells, mobile power generation, and automotive catalytic converters. State-of-the-art laboratory and computer simulation techniques will be engaged to explore the uncharted design space of bimetallic nanostructures for such applications and implement reductions in cost through partial replacement of precious metals such as platinum by cheaper alternatives. The team of three PIs will synthesize new nanocatalysts using biomimetic approaches, image the positions of all atoms in 3D resolution using the world's most powerful electron microscope, and carry out performance tests in fuel cells in a close feedback loop with predictions by multi-scale modeling and simulation. Fundamental understanding of synthesis controls, atomic-scale order, and associated reactivity of the nanoalloys will lead to rational design rules to optimize catalyst performance and enable targeted improvements of promising materials. The development and validation of predictive multi-scale simulation tools will also benefit the broader computational user community. New fundamental insight into alloy synthesis and reactivity controls has further potential benefits to improve catalysts for commodity chemicals, magnetic information storage, batteries, sensors, and nanoelectronic devices. Undergraduate students, high school students, and teachers will be engaged in summer research activities at UCLA and in annual Engineering Career Days at the University of Akron to encourage careers in science and engineering.Technical Description: The project focuses on the computationally driven, rational optimization of nanoalloy atomic composition and shape for catalytic performance in the Oxygen Reduction Reaction (ORR) in fuel cells. Specific aims include the deterministic synthesis of Pt-M Nanocrystals (M = Fe, Co, Ni, Cu, Cr, Mn), the three-dimensional characterization of nanoalloy catalysts in atomic resolution and model refinements, as well as the prediction, tests, and optimization of the reactivity in the ORR. Methods comprise biomimetic synthesis protocols coupled with molecular dynamics and kinetic Monte Carlo simulations, ORR performance testing by voltammetry and density functional theory calculations, and in-situ monitoring of all reactions. The coordinates of the atoms in the synthesized nanostructures will be monitored by electron tomography to identify atomic ordering, to validate and improve interatomic potentials, and to predict reaction rates in ORR. Detailed understanding of alloy growth mechanism, shape control, and catalytic performance through new polarizable and reactive force fields for alloys and their aqueous interfaces from first principles will close a wide gap between experimental capabilities and missing theoretical understanding. Aided by thorough experimental characterization, predictions with unprecedented accuracy at length scales of 1 to 100 nm appear feasible, far beyond the limits of quantum-mechanical methods and building on previous successful models for interfaces of pure metals (CHARMM-METAL).