(6cd) Rational Design of Pt-Ni Catalysts for the Oxygen Reduction Reaction By Building Atomic-Scale Structure-Property Relationships

Cao, L. - Presenter, Johns Hopkins University
Research Interests: Pt-Ni nanostructured materials are promising catalysts for the oxygen reduction reaction (ORR), but they suffer from Ni dissolution under cell operating conditions. To enable rational design of catalysts with improved stability and activity, I present the use of ab-initio calculations, cluster expansions, and Monte Carlo methods to study atomic-scale structure-property relationships for Pt-Ni surfaces and nanoparticles Using cluster expansions of Pt-Ni(111) surfaces, I built a direct bridge between the atomic structure and catalytic properties of Pt-Ni alloy surfaces at continuously varying strains, compositions and chemical environments. I investigated the synergy of strain and ligand effects in determining the catalytic activity, and demonstrated how this synergy can be leveraged to rationally design Pt-Ni surfaces with optimized ORR activity by searching for surfaces with targeted oxygen binding energy. For Pt-Ni nanoparticles, it has recently been shown that it is possible to stabilize octahedral Pt–Ni nanoparticles by alloying them with transition metals (e.g. Mo, Cu, Ga, and Rh). I discuss two examples of alloyed Pt-Ni nanoparticles: Mo-Pt-Ni and Cu-Pt-Ni. Using a kinetic Monte Carlo (KMC) model based on cluster expansions, I demonstrated that surface Mo oxides preferentially located on low-coordination sites help protect Ni in sub-surface layers against acid dissolution. KMC simulations reveal that the enhanced stability of Cu-Pt-Ni is likely due to the reduction of the number of Ni and Cu atoms on the surface during synthesis, reducing the opportunity for Ni and Cu atoms in sub-surface layers to move to the surface and dissolve.

Teaching Interests: During my Ph.D. period at Johns Hopkins University, I worked as a teaching assistant for two courses, General Physics and General Physics Lab for undergraduate with class sizes of 24. As a TA, I accumulated rich experience in teaching by preparing and giving weekly presentations, and holding weekly office hours. For my teaching interests, provided I have B.S and Ph.D. degrees in Physics (major in Condensed Matter Physics), I believe I am qualified for teaching courses related to condensed matter physics, such as Solid State Physics, Electromagnetics, Quantum Mechanics, and Statistical Mechanics, at both undergraduate and graduate levels. I also plan to develop a graduate-level lab-oriented course to introduce commonly used computational methods closely related to my research on nanomaterials for energy storage and conversion.