Unusual strain effect of a Pt-based L1 0 face-centered tetragonal core in core/shell nanoparticles for the oxygen reduction reaction

intermetallic structure. We have calculated the adsorption energies of O, OH and OOH on various Pt skins and the underlying tetragonally structured alloys, which allows us to not only predict the optimal number of pure Pt skin layers but also tune the activity of the catalysts toward the peak of the ORR volcano plot. More importantly, using adsorption energies on intermediate structures, we are able to decompose the enhancement factor into the ligand, normal and shear strain effects, and reveal the significant contribution of the shear strain that is only possible with a tetragonal core but not a cubic one. Our results point to a new direction in designing tetragonally structured intermetallic core-shell nanoparticles for ORR applications.