Cu(111)-supported W3Ox clusters: Stoichiometry and symmetry effects on CO2 activation and dissociation

Abstract

Density functional calculations with dispersion corrections (DFT-D) have been performed to study the adsorption and dissociation of CO2 on W3Ox/Cu(111) inverse catalyst (x = 9 or 6). The W3O9 aggregate adsorbs in several different geometries through the formation of O-Cu bonds, in all the cases taking electronic charge from the metal surface. The reduced W3O6 particle anchors very strongly to Cu by means of W-Cu bonds; in this case, the charge transfer is opposite than for W3O9/Cu yielding the oxide particle positively charged. CO2 is activated on W3O6/Cu(111) at the oxide/metal interface; its dissociation was found to be exothermic and kinetically more favorable than on the pure counterparts, Cu(111) and WO3(001) surfaces. In contrast, CO2 is activated on W3O9/Cu(111) only in the form that is by far the least stable (the one possessing Cs symmetry). Our results suggest that stoichiometry and symmetry of Cu-supported W3Ox clusters play a crucial role in CO2 activation and dissociation. In particular, the mixed W3O6/Cu(111) system appears as a catalyst of great potential for reactions involving CO2 dissociation.