(585g) Development of Predictive Models for Screening Multimetallic Electrocatalysts

Developing predictive models of chemisorption on metal surfaces is critical for the understanding of surface chemical reactions and rational design of efficient catalysts. It has been shown that the d-band model of chemisorption, developed by Hammer and Nørskov, can predict the trends in chemisorption energies of various adsorbates on metal surfaces. [1] The model correlates the central moment of the d-band projected on surface atoms (d-band center referenced to the Fermi level) with the surface reactivity. It has been used successfully to design novel metal surfaces for various catalytic reactions. In general, for a given adsorption geometry adsorbates bind to the surface of transition or noble metals more strongly if the d-band center of the surface atom is higher in energies. The model is very robust and most adsorbates follow the trends predicted by the model.

In this study, we show that there is a family of adsorbate-substrate systems that does not follow the trends in adsorption energies predicted by the d-band model. [2] We discuss this exception to the d-band model by analyzing hydroxyl (OH) adsorption on a series of Pt and Pd skin alloys. This exception is important since OH adsorption on metals is crucial for the understanding of various catalytic, electro-catalytic and photo-catalytic reactions including oxygen reduction and water splitting reactions. It has been shown previously that Pt and Pd skin alloys are promising alternatives to conventional Pt catalysts in these chemical transformations.  A physically transparent model with the incorporation of both the d-band center and the adsorbate-substrate bond length dependent chemisorptions energies has been developed for OH adsorption on Pt and Pd alloy surfaces and used to screen multimetallic electrocatalysts.