(53b) Predicting Bimetallic Catalyst Reconstruction and Performance from Molecular-Surface Interactions: A Case Study of Hydrogen Oxidation

To sustainably address our energy and chemical needs, new fundamental chemistries and technologies are required that will enable the creation of new energy and chemical feedstocks from carbon neutral sources. Multi-metallic catalysts leverage the properties of multiple metal components to offer improved catalytic performance for a range of applications, but the rapid and rational design of such catalysts is complicated by the tendency of such catalysts to reconstruct in response to the high adsorbate coverages present under realistic reaction conditions. Thus, there is a critical need for fundamental insight into the interplay between adsorbate-adsorbate, adsorbate-metal, and metal-metal interactions, as such interactions provide the driving force for surface reconstructions. Here, we combine density functional theory with microkinetic modeling over multi-faceted catalyst nanoparticles to characterize the interplay between the surface composition, adsorbates coverage, and performance under working conditions. Using hydrogen oxidation over Pt-based (PtM) and Ni-based (NiM) bimetallic catalysts as a case study, the addition of a second metal with varying properties (e.g. atomic radii, electronegativity, oxophilicity, d-band center, number of d-electrons) to the PtM or NiM nanoparticles significantly alters the surface coverages of H*, O*, and OH*, with O* and OH* dominating surface sites and forming distinct, facet-dependent regions. Simultaneous to changes in O*/OH* coverage during reaction, the structure and composition of the near surface layer of the catalyst nanoparticle reconstructs. Furthermore, we find that such adsorbate-induced nanoparticle reconstructions do not follow periodic trends, such as those observed in energies via BEP relations for identically structured surfaces. Overall, this work provides us a deeper understanding of how the nano-scale interactions between adsorbates and bimetallic surfaces drive the metal and adsorbate distributions on catalyst surfaces, as well as enable the real-world tuning of surface composition in bimetallic surfaces via applied gas phase carbon and oxygen chemical potentials.