UNS:Nanoporous Platinum -- Atomistic Structure and Catalytic Properties Via Computational Simulations

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Goddard (1512759)The proposal will utilize theoretical tools to obtain insight into structure-function relationships in fuel cell related catalysis by nanoporous metals. The nanoporous materials are not readily accessible by experimental probes due to the small spatial scale involved, their inherent complexity and disorder, and their high ratio of surface- to bulk-atom characteristics. The work will be directed at understanding a poorly understood, yet remarkable, experimental observation that nanoporous platinum obtained by electrochemical dealloying of Ni-Pt particles produces a dramatic optimum activity for the oxygen reduction reaction (ORR) at the Ni7Pt3 composition despite the observed lack of Ni near the surface of the active catalyst. The proposed work will contribute to the development of improved fuel cells for transportation and power applications. It will also provide educational opportunities related to fuel cell catalysis and methods of theoretical simulation of materials properties. The proposal will elucidate the structure-property relationships in the Ni-Pt and other bimetallic particles via first-principles-based theory, reactive molecular dynamics simulations (RMD) and global optimization techniques. The proposal is ambitious in scope, but the PI is a well-established computational scientist with a history of developing refined theoretical techniques and applying them successfully to important problems in catalysis and materials science. The proposal has the potential to be transformative in regards to its ability to gain insight into the properties of nanoscale alloy particles at levels not easily assessed by experimental methods. Novel features of the work include development of a computational method for modeling ORR under electrochemical potential and a plan to extract finite-sized clusters from the complete nanoparticles and subject them to deeper theoretical analysis of the surface properties with respect to adsorption and reaction processes involved in the ORR. Although the specific focus of the proposal is on understanding nanoporous multimetallic particles as they relate to electrocatalysis and use the understanding to design more efficient, durable, and lower-cost fuel cells, the potential impact of the work extends to many areas of nanoparticle application in the general areas of materials science and engineering. These include energy, sustainability, environmental factors, and economic considerations (e.g., non-noble metal materials). The PI is a leader in fuel cell catalysis. As Director of the Materials and Process Simulation Center at Caltech, he has access to a strong team of researchers at all levels to address the complicated interplay between the various components of fuel cell systems - namely catalysts, carbon supports, and polymer membranes. The PI will continue to make software developed in his lab available as open-source packages (i.e. LAMMPS). The PI also has a good track record of incorporating his research into learning oppportunities for minority underrepresented groups and has developed a course related to atomistic modeling of materials.