Adsorption and dehydrogenation of ethane, propane and butane on Rh13 clusters supported on unzipped graphene oxide and TiO2(110) - a DFT study.

The catalytic activity for the adsorption and dehydrogenation of alkanes (CnH2n+2, n = 2, 3, 4) on a low-symmetry Rh13 cluster (Rh13-Ls) is compared with a system consisting of the same cluster (Rh13-Ls) supported on either an unzipped graphene-oxide (UGO) sheet (Rh13-Ls/UGO) or a TiO2(110) surface (Rh13-Ls/TiO2). The adsorption energies of these alkanes, calculated using density-functional theory, follow the order Rh13-Ls/TiO2 ≈ Rh13-Ls/UGO > Rh13-Ls. Our proposed reaction path for the dehydrogenation of ethane, propane and butane on Rh13-Ls/UGO has first barrier heights of 0.21, 0.22 and 0.16 eV for the dissociation of a terminal C-H bond to form -C2H5, -C3H7 and -C4H9, respectively. Compared with the barriers on Rh13-Ls and Rh13-Ls/TiO2, the barrier on Rh13-Ls/UGO is the lowest for all alkanes. The calculated data, including the electronic distribution and the density of states of alkanes adsorbed on Rh13-Ls/UGO, Rh13-Ls and Rh13-Ls/TiO2, to support our results are presented.