Growth and structure of Cu, Ag and Au clusters on α-Fe2O3(0001): A comparative density functional study

CAROLINA ZUBIETA; AQUINO LINAREZ, LUIS G.; SILVIA A. FUENTE; PATRICIA BELELLI; FERULLO, RICARDO M.

COMPUTATIONAL MATERIALS SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020

0927-0256

Transition metals supported on metal oxide surfaces have broadapplications in heterogeneous catalysis, microelectronics, and gasdetection. For many uses, it is critical to control the dispersion of thesupported metals to obtain either atomically dispersed systems orisolated particles of controlled size. The morphology of the designedsurfaces is mainly governed by the relative intensities of the metalmetaland metal-oxide interactions. Here, we have investigated theadsorption of small Mn clusters (M = Cu, Ag and Au, with n = 1-5) on theFe- -Fe2O3 (hematite) by using the densityfunctional theory, including an on-site Coulomb term (DFT+U). The M-M andM-oxide interactions were quantified by computing the association andadhesion energies, respectively. Whereas the former is defined inrelation to an ideal atom-by-atom nucleation mechanism, the latter isdescribed considering the particle adsorption as a whole. In thenucleation process, the magnitude of the association energy follows theorder Au > Ag ≳ Cu. The M-oxide strength interaction (adhesion) was foundto follow a different trend: Cu >Ag ≳ Au. In other words, Cu, whichpresents the highest strength interaction with the surface, shows thelowest tendency to grow by nucleation; Au presents the opposite behavior:a relative weak interaction with the surface and a strong trend to growby nucleation. Ag exhibits an intermediate behavior being similar to Cuin nucleation and to Au in adhesion. Thus, for the formation of supportedclusters using evaporation/deposition techniques, the present resultssuggest that whereas Cu shows a tendency to disperse over the hematitesurface, Au tends to nucleate and to form large aggregates.