CO2 activation on small Cu-Ni and Cu-Pd bimetallic clusters

The use of CO2 to produce methanol is a reaction of growing interest, where bimetallic Cu-M catalysts become relevant as an alternative to the known Cu/Zn/Al2O3 catalyst. However, there is a lack in the understanding of bimetallic systems at atomic label and its capability towards CO2 activation, a key step in CO2 valorization. In this work, Cu-Pd and Cu-Ni small clusters are studied using DFT. Among the evaluated bimetallic systems, the binding of CO2 on Cu3Pd has the highest thermodynamics stability (28.82 kcal/mol) and the lowest energy barrier (40.91 kcal/mol). The activation energy for the dissociation of CO2 (CO2* -> CO* + O*) follows the trend: Cu-4 < Cu3Pd < Pd-4 < CuPd3 < Cu2Pd2. Therefore, the ideal composition in terms of adsorption energy and activation barrier is the Cu3Pd bimetallic system. The interaction O-M is weak while C-M is responsible of the binding, a charge migration from cluster to CO2 was seen, and the band around 1150 cm(-1) in the IR was only found in activated CO2. The results of this work indicate that the Cu3Pd cluster has catalytic potential towards CO2 activation and dissociation, opening the doors to explore further the Cu3Pd system both theoretically and experimentally.