“Theoretical Investigations of Transition-Metal Surface Energies Under Lattice Strain and CO Environment” published with Michael Tang and Karen Chan from Stanford in JPC-C. Full abstract below!
An understanding of the relative stability of surface facets is crucial in order to develop predictive models of catalyst activity and to fabricate catalysts with controlled morphology. In this work, we present a systematic density functional theory (DFT) study of the effect of lattice strain and of a CO environment on the surface formation energies of Cu, Pt, and Ni. First, we show both compressive and tensile lattice strain favors the formation of stepped vs. low-index terraces such as (111) and (100). Then, we investigate the effect of a CO environment using configurations of CO at various coverages, determined using a greedy, systematic approach, inspired by forward stepwise feature selection. We find that a CO environment favors stepped facets on Ni, Cu and Pt. These trends are illustrated with the corresponding equilibrium Wulff shapes at various strain and CO pressures. In general, the surface energies of the studied transition metals are highly sensitive to strain and CO coverage, which should be considered when rationalizing trends in catalytic activity.