We have developed a multiscale Quantum Mechanics/Molecular Mechanics (QM/MM) method to study strain effect on oxygen reduction reaction (ORR) based on Cu-Pt core-shell nanoparticles. The multiscale method allows us to examine particle sizes ranging from 3 nm to 8 nm, far beyond the present capability of QM simulations. We have determined the oxygen adsorption energy - the well-established descriptor for ORR activity - as a function of nanoparticle size and thickness of Pt shell. We find that the Pt-Cu core-shell nanoparticles have higher ORR activities than the flat Pt (111) surface, consistent with experiments. We predict that the optimal size of the nanoparticle should exceed 7 nm in order to reach the volcano peak of ORR activity. By examining the effects of �ligand�, strain and quantum confinement, we conclude that the enhanced ORR activity of the core-shell particles is entirely due to the strain on the Pt shell. The correlations between the oxygen adsorption energy, strain and d-band center shift are established, from which a simple computational strategy can be envisaged to quickly screen and/or guide the design of core-shell particles for superior ORR performance.

Multiscale modeling of strain effect on core-shell nanoparticles for oxygen reduction reaction

246th National Meeting (2013)

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