Pd3 and Pt3 species on the α-Al2O3(0001) surface: cluster models embedded in an elastic polarizable environment

Density functional embedded cluster calculations on Lewis acid centers of the α‐Al2O3(0001) surface: Adsorption of a CO probe

“…When a crystal is cleaved to form a polar surface, the type of termination defines the value and direction of the surface dipole moment and the extent of the subsequent relaxation. The remaining dipole moment affects the adsorption properties of the surface 37. From a refinement of the grazing incidence X‐ray scattering (GIXS) data, it has been concluded that the α‐Al 2 O 3 (0001) surface is terminated by a single layer of Al 3+ cations 34.…”

Pd diffusion on MgO(100): The role of defects and small cluster mobility

“…The most stable flat timer, T3, has a Pd atom next to D1 forming a triangle on oxygen sites with two Pd-Pd bond lengths of 2.72 Å and one stretched bond of 3.02 Å . T3 has an adsorption energy of 5.25 eV (1.75 eV/ atom), which is 0.44 eV less stable than the lowest energy vertical trimer, T1; similarly, vertical Pd trimers have been also predicted to be 0.4 eV more stable than flat ones in a recent study of Pd 3 /a-Al 2 O 3 (0 0 0 1) [52].…”

Surface termination effects on metal atom adsorption on α-alumina

“…At high exposures of water, this dissociation process is found in simulation [11,[17][18][19] and experiments [16,20] to terminate in the formation of a fully hydroxylated surface that resembles gibbsite, or Al(OH) 3 indicates that it too can expose both unhydroxylated and hydroxylated surfaces under practically relevant conditions [21]. The structures and mechanisms of metal atom adsorption on the dry alumina surface have been explored using density functional theory (DFT) simulations, although general consensus has not always been achieved [22][23][24][25][26][27][28][29][30]. For instance, Hinnemann and Carter have described the adsorption of Pt atoms on the dry alumina surface in terms of Pt-O covalent bonding [22], while a more ionic bond with charge transfer from Pt to O was proposed by Verdozzi et al [23] Pd has been found to bind more weakly to the dry surface than does Pt [22,25], although again the mechanism of Pd binding has been debated [23][24][25][26][27].…”

“…The structures and mechanisms of metal atom adsorption on the dry alumina surface have been explored using density functional theory (DFT) simulations, although general consensus has not always been achieved [22][23][24][25][26][27][28][29][30]. For instance, Hinnemann and Carter have described the adsorption of Pt atoms on the dry alumina surface in terms of Pt-O covalent bonding [22], while a more ionic bond with charge transfer from Pt to O was proposed by Verdozzi et al [23] Pd has been found to bind more weakly to the dry surface than does Pt [22,25], although again the mechanism of Pd binding has been debated [23][24][25][26][27]. The binding of Ag and Au is reported to be much weaker than that of Pd and Pt [23,[28][29][30].…”