Theoretical Study on the Aggregation of Copper Clusters on a Liquid Surface

Optimal Icosahedral Copper-Based Bimetallic Clusters for the Selective Electrocatalytic CO2 Conversion to One Carbon Products

Electrochemical CO2 reduction reactions can lead to high value-added chemical and materials production while helping decrease anthropogenic CO2 emissions. Copper metal clusters can reduce CO2 to more than thirty different hydrocarbons and oxygenates yet they lack the required selectivity. We present a computational characterization of the role of nano-structuring and alloying in Cu-based catalysts on the activity and selectivity of CO2 reduction to generate the following one-carbon products: carbon monoxide (CO), formic acid (HCOOH), formaldehyde (H2C=O), methanol (CH3OH) and methane (CH4). The structures and energetics were determined for the adsorption, activation, and conversion of CO2 on monometallic and bimetallic (decorated and core@shell) 55-atom Cu-based clusters. The dopant metals considered were Ag, Cd, Pd, Pt, and Zn, located at different coordination sites. The relative binding strength of the intermediates were used to identify the optimal catalyst for the selective CO2 conversion to one-carbon products. It was discovered that single atom Cd or Zn doping is optimal for the conversion of CO2 to CO. The core@shell models with Ag, Pd and Pt provided higher selectivity for formic acid and formaldehyde. The Cu-Pt and Cu-Pd showed lowest overpotential for methane formation.

Cu n Clusters (n = 13, 43, and 55) as Possible Degradant Agents of mSF6 Molecules (m = 1, 2): A DFT Study

In order to obtain the structural and electronic properties of pristine copper clusters and Cu₁₃-SF₆, Cu₄₃-SF₆, Cu₅₅-SF₆, Cu₁₃-2SF₆, Cu₄₃-2SF₆, and Cu₅₅-2SF₆ systems, DFT calculations were carried out. For Cu₁₃-mSF₆, its surface suffers a drastic deformation, and Cu₄₃-mSF₆ at its outer surface reveals strong interaction for the first chemical molecule; when the second molecule is interacting, these outer surfaces are not severely affected. These two cases degraded fully the first SF₆ molecule; however the second molecule is bonded to the latter systems and for Cu₅₅-mSF₆ (m = 1 and 2) a structural transformation from SF₆ →SF₄ appears as well as inner and outer shells that display slight deformations. The electronic gaps do not exhibit drastic changes after adsorption of mSF₆ molecules, and the magnetic moment remains without alterations. The whole system shows thermal and vibrational stability. In addition, for Cu₁₃-mSF₆ the values of the optical gap and intensity of the optical exhibit changes with respect to the pristine case (Cu₁₃), and the rest of the systems do not exhibit major oscillations. These icosahedral copper clusters emerge as a good option to degrade mSF₆ molecules.