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

Abstract

The catalytic activity for the adsorption and dehydrogenation of alkanes (C_nH_2n+2, n = 2, 3, 4) on a low-symmetry Rh₁₃ cluster (Rh₁₃-L_s) is compared with a system consisting of the same cluster (Rh₁₃-L_s) supported on either an unzipped graphene-oxide (UGO) sheet (Rh₁₃-L_s/UGO) or a TiO₂(110) surface (Rh₁₃-L_s/TiO₂). The adsorption energies of these alkanes, calculated using density-functional theory, follow the order Rh₁₃-L_s/TiO₂ ≈ Rh₁₃-L_s/UGO > Rh₁₃-L_s. Our proposed reaction path for the dehydrogenation of ethane, propane and butane on Rh₁₃-L_s/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-L_s and Rh₁₃-L_s/TiO₂, the barrier on Rh₁₃-L_s/UGO is the lowest for all alkanes. The calculated data, including the electronic distribution and the density of states of alkanes adsorbed on Rh₁₃-L_s/UGO, Rh₁₃-L_s and Rh₁₃-L_s/TiO₂, to support our results are presented.