Size effect on the adsorption and dissociation of CO2 on Co nanoclusters

Spin-polarized density functional theory calculations were carried out to study the adsorption and dissociation properties of CO₂ on size-selected Co₁₃, Co₃₈ and Co₅₅ nanoclusters. Based on genetic algorithm method, Co₁₃, Co₃₈ and Co₅₅ nanoclusters were predicted as the most stable high-symmetry structures among these Con (n = 2–58) nanoclusters from the Gupta potential. For the adsorption of CO₂, CO and O on size-selected Co₁₃, Co₃₈ and Co₅₅ nanoclusters, the lowest adsorption strength is found for all the different adsorbates on Co₅₅ nanocluster. For the dissociation of CO₂ on these size-selected Co nanoclusters, the largest Co₅₅ nanocluster possesses the greatest catalytic activity for the dissociation of CO₂, with the smallest reaction barrier of 0.38 eV. Our results reveal a non-monotonous behavior of the catalytic activities of Co nanoclusters on size, which is of fundamental interest for the design of new Co catalysts for the conversion of CO₂.