Dissociation of CO₂ on rhodium nanoclusters (Rh₁₃) in various structures supported on unzipped graphene oxide - A DFT study

The catalytic activity of rhodium nanoclusters (Rh₁₃) on unzipped graphene oxide (Rh₁₃/UGO) has been investigated for comparison with Rh₁₃ nanoclusters and Rh(111) surfaces. The binding energy of Rh atoms on UGO is less than the cohesive energy (-5.75 eV) of bulk Rh, indicating that the Rh atoms adsorbed on UGO tend to collect into clusters. We systematically calculated the adsorption energies of CO₂ on Rh₁₃ nanoclusters in various stable shapes on unzipped graphene oxide; Rh₁₃-I_h/UGO had the highest energy (where the I_h represents icosahedral shape), -1.18 eV, with the C-O bond being elongated from 1.17 to 1.29 Å; the barrier to dissociation of CO₂ on Rh₁₃-I_h/UGO is, accordingly, the smallest (E_a = 0.45 eV), indicating that Rh₁₃-I_h/UGO might act as an effective material to adsorb and activate the scission of the C-O bond of CO₂. The calculated data required to support all evidence of this result, including the electronic distribution and the density of states, are provided.