Transition and noble metal clusters have proven to be critical novel materials, potentially offering major advantages over conventional catalysts in a range of value-added catalytic processess such as carbon dioxide transformation to methanol. In this work, a systematic computational study of CO₂ adsorption on gas-phase Cu_4−xPt_x (x = 0–4) clusters is performed. An exhaustive potential energy surface exploration is initially performed using our recent density functional theory basin-hopping global optimization implementation. Ground-state and low-lying energy isomers are identified for Cu_4−xPt_x clusters. Secondly, a CO₂ molecule adsorption process is analyzed on the ground-state Cu_4−xPt_x configurations, as a function of cluster composition. Our results show that the gas-phase linear CO₂ molecule is deformed upon adsorption, with its bend angle varying from about 132° to 139°. Cu_4−xPt_x cluster geometries remain unchanged after CO₂ adsorption, with the exception of Cu₃Pt₁ and Pt₄ clusters. For these particular cases, a structural conversion between the ground-state geometry and the corresponding first isomer configurations is found to be assisted by the CO₂ adsorption. For all clusters, the energy barriers between the ground-state and first isomer structures are explored. Our calculated CO₂ adsorption energies are found to be larger for Pt-rich clusters, exhibiting a volcano-type plot. The overall effect of a hybrid functional including dispersion forces is also discussed.

Transition metal particles dispersed on oxide supports are used as heterogeneous catalysts in numerous applications. One example is platinum clusters supported on ceria which is used in automotive catalysis. Although control at the nm-scale is desirable to open new technological possibilities, there is limited knowledge both experimentally and theoretically regarding the geometrical structure and stability of sub-nanometer platinum clusters supported on ceria. Here we report a systematic, Density Functional Theory (DFT) study on the growth trends of CeO₂(111) supported Pt_N clusters (N = 1–10). Using a global optimization methodology as a guidance tool to locate putative global minima, our results show a clear preference for 2D planar structures up to size Pt₈. It is followed by a structural transition to 3D configurations at larger sizes. This remarkable trend is explained by the subtle competition between the formation of strong Pt–O bonds and the cluster internal Pt–Pt bonds. Our calculations show that the reducibility of CeO₂(111) provides a mechanism to anchor Pt_N clusters where they become oxidized in a two-way charge transfer mechanism: (a) an oxidation process, where O_surface atoms withdraw charge from Pt atoms forming Pt–O bonds, (b) surface Ce⁴⁺ atoms are reduced, leading to Ce³⁺. The active role of the CeO₂(111) support in modifying the structural and eventually the chemical properties of sub-nanometer Pt_N clusters is computationally demonstrated.

Controlling Ce ⁴⁺ to Ce ³⁺ electronic reducibility in a rare-earth binary oxide such as CeO ₂ has enormous applications in heterogeneous catalysis, where a profound understanding of reactivity and selectivity at the atomic level is yet to be reached.

We present a systematic study on the adsorption properties of molecular oxygen on Pt, Ni and PtNi clusters previously deposited on MgO(100) by means of density functional theory calculations. We map the different adsorption sites for a variety of cluster geometries, including icosahedra, decahedra, truncated octahedra and cuboctahedra, in the size range between 25–58 atoms. The average adsorption energy depends on the chemical composition, varying from 2 eV for pure Ni, 1.07 for pure Pt and 1.09 for a Pt ${}_{shell}$ Ni ${}_{core}$ nanoalloy. To correlate the adsorption map to the adsorption properties, we opt for a geometrical descriptor based on the metallic coordination up to the second coordination shell. We find an almost linear relationship between the second coordination shell and adsorption energy, with low coordination sites, such as those located at the (111)/(111) and (111)/(100) cluster edges-displaying adsorption energies above 1 eV, while higher coordination sites such as (111) cluster facets have an interaction of 0.4 eV or lower. The inclusion of van der Waals corrections leads to an overall increase of the O ${}_2$ adsorption energy without an alteration of the general adsorption trends.

A genetic search algorithm in conjunction with density functional theory calculations was used to determine the lowest-energy minima of the pure B ₂₂ cluster and thereby to evaluate the capacity of its isomers to form endohedrally doped cages.