Adsorption and dehydrogenation of ethane, propane and butane on Rh 13 clusters supported on unzipped graphene oxide and TiO 2 (110) - a DFT study.

The catalytic activity for the adsorption and dehydrogenation of alkanes (C _n H _2n+2 , n = 2, 3, 4) on a low-symmetry Rh ₁₃ cluster (Rh ₁₃ -L _s ) is compared with a system consisting of the same cluster (Rh ₁₃ -L _s ) supported on either an unzipped graphene-oxide (UGO) sheet (Rh ₁₃ -L _s /UGO) or a TiO ₂ (110) surface (Rh ₁₃ -L _s /TiO ₂ ). The adsorption energies of these alkanes, calculated using density-functional theory, follow the order Rh ₁₃ -L _s /TiO ₂ ≈ Rh ₁₃ -L _s /UGO > Rh ₁₃ -L _s . Our proposed reaction path for the dehydrogenation of ethane, propane and butane on Rh ₁₃ -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 -C ₂ H ₅ , -C ₃ H ₇ and -C ₄ H ₉ , respectively. Compared with the barriers on Rh ₁₃ -L _s and Rh ₁₃ -L _s /TiO ₂ , the barrier on Rh ₁₃ -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 Rh ₁₃ -L _s /UGO, Rh ₁₃ -L _s and Rh ₁₃ -L _s /TiO ₂ , to support our results are presented.