Theoretical study for the adsorption of CO on neutral and charged Pd₁₃ clusters

Abstract

Adsorption of carbon monoxide, CO, on the surface of magnetic Pd13, Pd13–, and Pd13+ clusters, showing magnetic moments of 8, 7, and 7 Bohr magnetons (μB), respectively, was studied by means of density functional methods, allowing partial inclusion of relativistic effects. The favorable adsorption modes are on top, bridge, and threefold, with the binding energy of CO with Pd13– increasing in this same order as 39.4, 48.0 and 50.2 kcal/mol. In addition, the experimental results for the [Pdn–CO]–, n = 4–12, anions show a decrease of the vibrational frequency of CO along this triad of modes, 1940, 1800, and 1680 cm−1, with respect to the free CO value, 2143 cm−1, which conforms to our estimated frequencies, 1956, 1784, and 1679 cm−1, for CO in the [Pd13–CO]– complex. Also, the threefold mode shows a significantly longer bond length for CO, 1.210 Å, with respect to the free case, 1.139 Å. Then the bond of CO is considerably weakened in the negatively charged [Pd13CO]– cluster when the adsorption occurs in a threefold site. These results are mainly accounted for by charge transfer effects from the Pd13 cluster to the CO molecule. Smaller CO activation was found in neutral Pd13–CO and in [Pd13–CO]+, where hollow adsorption yields bigger structural and electronic changes on CO than the respective bridge and on-top modes. Overall, CO adsorption notably quenches the magnetization of neutral and charged Pd13 particles.

Developing Efficient Suzuki Cross-Coupling Catalysts by Doping Palladium Clusters with Silver

“…The valence region is dominated by ↓ spin orbitals, and the HOMO ↑ orbital lies much lower in energy. Hence, the unusually low HOMO ↓ –LUMO ↓ gap (0.14 eV) can be considered as the reason for the observed high reactivity of the icosahedral Pd 13 cluster . The MO composition analysis reveals that the HOMO ↓ of Pd 13 is mostly composed of Pd d orbitals, whereas the LUMO ↓ shows a hybrid composition of d and s orbitals of Pd atoms.…”

Hydrogen Generation from Water Splitting by 3H2O + Pd13 → 3H2 + Pd13O3 Reaction

“…[ 14 ] have reported that the process of hydrogen production on the Fe n + ( n = 6–15) cluster in experimentally and shown the intrinsic reaction coordinate (IRC) of water dissociated into OH+H by two energy barriers on icosahedra Fe 13 + in theoretically. Benítez et al [ 15 ] theoretically studied the adsorption of CO on neutral and charged Pd 13 clusters by DFT. The adsorption and dissociation of H 2 on the Pd n ( n = 4, 6, 13, 19, 55) clusters have also been studied using DFT by Liu et al [ 16 ] The study on the hydrogen storage in the cuboctahedra Pd 13 H n clusters with n = 1, 6, 8, and 14 has also been reported.…”