Rational Design of Bimetallic Metal Chalcogenide Clusters for CO 2 Dissociation.

Thermochemical dissociation of CO 2 on pure, ligated, and mixed transition metal (W, Cu) chalcogenide clusters are investigated using the first-principles gradient-corrected density functional approach. It is shown that although the pure and ligated metal chalcogenide clusters exhibit significantly high barriers for CO 2 dissociation, the computed barriers for the mixed clusters are relatively lower. The lowest barrier is obtained for the Cu 3 W 3 Se 8 cluster, which shows a dramatically reduced barrier height of only 0.41 eV. Detailed analysis reveals that the substitution of W by Cu sites leads to a charge transfer from Cu to W sites, resulting in locally active W sites. The lowering of the CO 2 dissociation barriers can be attributed to the facile transfer of charge from the locally active W sites and also due to the alteration of the binding energy of CO 2 to the charged W sites. Our studies provide an alternate strategy to design novel thermochemical catalysts for CO 2 adsorption and subsequent dissociation.