Computational Study of Site-Specific Correlations among Oxygen Reduction Intermediates on Pd3Y (111)

Abstract

In recent years, Pd3Y (111) alloy system has emerged as one of promising catalyst materials for oxygen reduction chemistry. This system is used in this work as a model system to study the site-specific adsorption energies of 4 ORR intermediates, O, OH, H2O, and OOH. Trends in energetics are estimated to assess the presence of scaling correlations among the adsorbates. Two types of site mappings are introduced and applied in correlating the energy of an adsorbed oxygen atom on hollow sites to its equivalent adsorption energies on top sites. Both types demonstrate relevant correlations to the other 3 intermediates, one correlates with OOH, and the other with H2O and OH. Discrepancies in energetic trends are explained in light of calculated charge densities and their implying effect on the observed correlations. OH and H2O strongly interact with the second layer of slab and the ground state adsorption of O, while OOH adsorption does not coincide with the second layer charge and correlates instead with its average effect that is reflected in the average adsorption energy of atomic oxygen. The results indicate how the energetics of one type of surface site may be affected by the energetics on another type. The underlying approach of site-mappings is expected to find high application in screening of catalyst materials using computational chemistry.