Theoretical Studies on Suppression of Carbon Deposition over Titania Supported Monometallic Nickel(Platinum) Catalysts in Methane Dissociation

The adsorption behavior of carbon atom adsorbed by one atom of Ni or Pt supported on the anatase TiO2(101) surface was studied which could provide a thermodynamics clue for elucidating the carbon deposition. The calculated results by PBE based on generalized gradient approximation indicated that the adsorption energy of the most stable configuration for Ni and Pt adsorbed on the TiO2 surface were 347.16 and 315.9 kJ/mol, respectively, corresponding to the bridge site between the two O-2e atoms. After adsorbing metal atom, the density of state for TiO2 moved to the lower energy, leading to a more stable system. The density of state was confirmed that there was a significant overlap between p-orbital of carbon atom and d-levels of the metal atom, indicating the effective bonding of carbon and metal atoms, which could attenuate the interaction between these two atoms. When carbon was adsorbed on the Ni/TiO2(101) or Pt/TiO2(101) surface, the adsorption energies for the preferable structure were 474.19 or 570.08 kJ/mol. Our work demonstrates the Pt supported on TiO2 support possessed the better ability for inhibiting the carbon deposition.