Structures, Energetics, and Reaction Barriers for CH_x Bound to the Nickel (111) Surface

To provide a basis for understanding and improving such reactive processes on nickel surfaces as the catalytic steam reforming of hydrocarbons, the decomposition of hydrocarbons at fuel cell anodes, and the growth of carbon nanotubes, we report quantum mechanics calculations (PBE flavor of density functional theory, DFT) of the structures, binding energies, and reaction barriers for all CH_x species on the Ni(111) surface using periodically infinite slabs. We find that all CH_x species prefer binding to μ3 (3-fold) sites leading to bond energies ranging from 42.7 kcal/mol for CH_3 to 148.9 kcal/mol for CH (the number of Ni-C bonds is not well-defined). We find reaction barriers of 18.3 kcal/mol for CH_(3,ad) → CH_(2,ad) + H_(ad) (with ΔE = +1.3 kcal/ mol), 8.2 kcal/mol for CH_(2,ad) → CH_(ad) + H_(ad) (with ΔE = -10.2 kcal/mol) and 32.3 kcal/mol for CH_(ad) → C_(ad) + H_(ad) (with ΔE = 11.6 kcal/mol). Thus, CH_(ad) is the stable form of CH_x on the surface. These results are in good agreement with the experimental data for the thermodynamic stability of small hydrocarbon species following dissociation of methane on Ni(111) and with the intermediates isolated during the reverse methanation process.

[1]  A. V. Duin,et al.  Single-Site Vanadyl Activation, Functionalization, and Reoxidation Reaction Mechanism for Propane Oxidative Dehydrogenation on the Cubic V4O10 Cluster , 2007 .

[2]  G. Henkelman,et al.  Theoretical calculations of CH4 and H2 associative desorption from Ni(111): could subsurface hydrogen play an important role? , 2006, The Journal of chemical physics.

[3]  G. Ciccotti,et al.  Ab initio simulation of carbon clustering on an Ni(111) surface: a model of the poisoning of nickel-based catalysts. , 2006, The journal of physical chemistry. B.

[4]  Jannik C. Meyer,et al.  Versatile Synthesis of Individual Single-Walled Carbon Nanotubes from Nickel Nanoparticles for the Study of Their Physical Properties , 2004 .

[5]  I. Chorkendorff,et al.  Dissociation of CH4 on Ni(111) and Ru(0001) , 2002 .

[6]  A. Michaelides,et al.  A first principles study of CH3 dehydrogenation on Ni(111) , 2000 .

[7]  A. Michaelides,et al.  A density functional theory study of CH2 and H adsorption on Ni(111) , 2000 .

[8]  A. Michaelides,et al.  Methyl chemisorption on Ni(111) and C-H-M multicentre bonding : a density functional theory study , 1999 .

[9]  W. Goddard,et al.  Chemisorption of Organics on Platinum. 1. The Interstitial Electron Model , 1998 .

[10]  D. Truhlar,et al.  Embedded Diatomics-in-Molecules Potential Energy Function for Methyl Radical and Methane on Nickel Surfaces , 1998 .

[11]  C. Au,et al.  A DETAILED THEORETICAL TREATMENT OF THE PARTIAL OXIDATION OF METHANE TO SYNGAS ON TRANSITION AND COINAGE METAL (M) CATALYSTS (M = NI, PD, PT, CU) , 1998 .

[12]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[13]  Ming Wah Wong,et al.  Vibrational frequency prediction using density functional theory , 1996 .

[14]  Bloomfield,et al.  Surface-enhanced magnetism in nickel clusters. , 1996, Physical review letters.

[15]  K. J. Maynard,et al.  THE STRUCTURE AND CHEMISTRY OF CH3 AND CH RADICALS ADSORBED ON NI(111) , 1995 .

[16]  van Ra Rutger Santen,et al.  Methane activation and dehydrogenation on nickel and cobalt : a computational study , 1995 .

[17]  A. Jansen,et al.  Electronic structure calculations and dynamics of the chemisorption of methane on a Ni(111) surface , 1993 .

[18]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[19]  Johansson,et al.  Surface magnetism in iron, cobalt, and nickel. , 1992, Physical review. B, Condensed matter.

[20]  I. Alstrup,et al.  The kinetics of carbon formation from CH4 + H2 on a silica-supported nickel catalyst , 1992 .

[21]  Hong Yang,et al.  Chemisorption of atomic H and CHx fragments on Ni(111) , 1991 .

[22]  P. Siegbahn,et al.  A theoretical study of CHx chemisorption on the Ni(100) and Ni(111) surfaces , 1990 .

[23]  Jena,et al.  Magnetism and local order: Ab initio tight-binding theory. , 1989, Physical review. B, Condensed matter.

[24]  Per E. M. Siegbahn,et al.  A theoretical study of methyl chemisorption on Ni(111) , 1988 .

[25]  S. T. Ceyer,et al.  Summary Abstract: The stability and chemistry of methyl radicals adsorbed on Ni(111) , 1988 .

[26]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[27]  B. D. Kay,et al.  Kinetics of the activated dissociative adsorption of methane on the low index planes of nickel single crystal surfaces , 1987 .

[28]  R. Hayes,et al.  Surface intermediates in the nickel catalysed methanation of carbon monoxide as revealed by computer enhanced multiple reflectance infrared spectroscopy , 1983 .

[29]  W. H. Weinberg,et al.  Chemisorption geometry of hydrogen on Ni(111): Order and disorder , 1979 .

[30]  Jens R. Rostrup-Nielsen,et al.  Theoretical Studies of Stability and Reactivity of CHx Species on Ni(111) , 2000 .

[31]  I. Alstrup.  On the kinetics of CO methanation on nickel surfaces , 1995 .

[32]  A. Jansen,et al.  Theoretical investigation of CH4 decomposition on Ni: electronic structure calculations and dynamics , 1993 .

[33]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[34]  J. D. Beckerle,et al.  The Mechanism for the Dissociation of Methane on a Nickel Catalyst , 1988 .

[35]  A. K. Niessen,et al.  Cohesion in metals , 1988 .

[36]  Nicholas Winograd,et al.  Direct SIMS Observation of Methylidyne, Methylene, and Methyl Intermediates on a Ni(111) Methanation Catalyst , 1986 .

[37]  Jens R. Rostrup-Nielsen,et al.  Catalytic Steam Reforming , 1984 .

[38]  W. A. Miller,et al.  Surface free energies of solid metals: Estimation from liquid surface tension measurements , 1977 .