When reconstruction comes around: Ni, Cu, and Au adatoms on d-MoC(001)

Abstract

The interaction of Au, Cu, and Ni metal atoms with the δ-MoC(001) surface was studied using periodic Density Functional (DF) calculations to analyse adsorption energies and equilibrium geometries, work functions, atomic charges, Projected Density Of States (PDOS), and shifts of the transition metal d-band center. The atomic adsorption is found to cause an in-plane distortion of the surface, and, besides, the interaction strength turns to be coverage dependent. A lower coverage allows for a better accommodation of the adsorbate, alongside causing a d-band centre shift to more negative energies, as shown by plots of the PDOS. Regardless of the coverage, interaction strength diminishes following the order Ni > Cu > Au. Adatom chemical activity can be inferred based on the calculated d-band centre; Ni being the most active metal, followed by Cu, and Au later on for every coverage studied. This result correlates well with experiments on other transition metal carbides. Atomic adsorption also notably diminishes surface work function, with the concomitant repercussions on the electrocatalysis field.