The interaction of ammonia with transition metal carbide surfaces

Fernandez-Torres, Luis; Perry, Scott S.; Didziulis, Stephen V.; Frantz, Peter

doi:10.1016/s0039-6028(02)01559-5

Cited by 25 publications

(26 citation statements)

References 31 publications

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“…XPS measurements revealed a 1:1 V to C surface stoichiometry. The cleaning procedure of the VC(100) surface has been previously described [11]. The adsorbates, ethyl acetate, triethyl phosphate, and trimethyl phosphate, were purchased from Aldrich and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

et al. 2005

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This report presents ultrahigh vacuum measurements of the frictional properties of the non-polar (100) surface of vanadium carbide (VC) as a function of the room temperature uptake and reaction of ethyl acetate, triethyl phosphate, and trimethyl phosphate. Atomic force microscopy, employing a silicon nitride probe tip, has been used to determine the changes in friction and interfacial adhesion as a function of adsorbate uptake. Changes in surface morphology have been monitored with scanning tunneling microscopy while the composition of the surface species formed through the reaction of these adsorbates with the VC surface has been determined by X-ray photoelectron spectroscopy. Adsorption and reaction of ethyl acetate leads to an increase in friction with little change in interfacial adhesion. The adsorption and reaction of triethyl phosphate and trimethyl phosphate have no influence on either the friction or adhesion properties of VC. The observed results are discussed in terms of the surface chemical composition, the extent of surface coverage, and the molecular details of the adsorbed species.

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Section: Methodsmentioning

confidence: 99%

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

et al. 2005

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“…8,17,20,32 In the present paper, a set of DFT calculations is carried out to study SO 2 adsorption on Ti carbides, which are representative of transition metal carbides with good catalytic performances. 25,33,34 Several kinds of geometrical structures with different C/Ti a͒ Author to whom correspondence should be addressed. Fax: 631-344-5815; Electronic mail: rodrigez@bnl.gov ratios are taken into account.…”

Section: Introductionmentioning

confidence: 99%

Interaction of sulfur dioxide with titanium–carbide nanoparticles and surfaces: A density functional study

Liu

Rodríguez

2003

The Journal of Chemical Physics

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Articles you may be interested inElectronic, magnetic structure and water splitting reactivity of the iron-sulfur dimers and their hexacarbonyl complexes: A density functional study A density functional theory study of the dissociation of H 2 on gold clusters: Importance of fluxionality and ensemble effects Adsorption, diffusion, and dissociation of molecular oxygen at defected TiO 2 (110): A density functional theory study J. Chem. Phys. 120, 988 (2004); 10.1063/1.1631922Combining density-functional calculations with kinetic models: NO/Rh (111) In the control of environmental pollution, metal carbides are potentially useful for trapping and destroying sulfur dioxide (SO 2 ). In the present study, the density functional theory was employed to study the surface structures and electronic properties of the adsorbed SO 2 on titanium carbides: metcar Ti 8 C 12 , nanocrystal Ti 14 C 13 , and a bulk TiC͑001͒ surface. The geometries and orientations of SO 2 were fully optimized on all these substrates. Our calculations show that, in spite of the high C/Ti ratio and C 2 groups, metcar Ti 8 C 12 exhibits extremely high activity towards SO 2 . The S-O bonds of SO 2 spontaneously break on Ti 8 C 12 . The products of the decomposition reaction ͑S, O͒ interact simultaneously with Ti and C sites. The C atoms are not simple spectators, and their participation in the dissociation of SO 2 is a key element for the energetics of this process. Nanocrystal Ti 14 C 13 also displays a strong interaction with SO 2 . Although the dissociation of SO 2 on Ti 14 C 13 cannot proceed as easily as that on Ti 8 C 12 , it could occur by thermal activation even at very low temperature. SO 2 is weakly bonded with the bulk TiC͑001͒ surface. By thermal activation the dissociation of SO 2 on a TiC͑001͒ surface may also take place but it should be much more difficult than that on Ti 14 C 13 . Therefore, we suggest that the carbide nanoparticles (Ti 8 C 12 and Ti 14 C 13 ) should have special chemical activity towards SO 2 removal associated with their ''magic'' structures.

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“…The distance between the H 2 ͑NH 3 ͒ molecule and the TM atom is ϳ1.9 ͑ϳ2.2͒ Å and the bond length of the H 2 molecules is slightly elongated to ϳ0.83 Å from 0.75 Å for an isolated molecule. According to reference, 23 TM-H 2 complexes are observed, and the hybridization of the TM d states with the NH 3 states as well as the induced polarization of the NH 3 molecule both contribute to the NH 3 binding.…”

Section: Resultsmentioning

confidence: 90%

ReleasingH2molecules with a partial pressure difference without the use of temperature

et al. 2010

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Using the pseudopotential density-functional method as well as equilibrium thermodynamic functions, we explore the process of releasing H 2 molecules adsorbed on a transition-metal atom caused by the hydrogenammonia partial pressure difference. The H 2 molecules bind to a transition-metal atom at H 2 pressure-NH 3 pressure-temperature 50 atm-10 −9 atm-25°C, and they are released at 3 atm-10 −6 atm-25°C. This process involves the same mechanism responsible for carbon monoxide poisoning of hemoglobin with the O 2 -CO partial pressure difference. We show that our findings can be applicable to an approach to induce hydrogen desorption on nanostructured hydrogen-storage materials without the need for increasing temperature.

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The interaction of ammonia with transition metal carbide surfaces

Cited by 25 publications

References 31 publications

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

Interaction of sulfur dioxide with titanium–carbide nanoparticles and surfaces: A density functional study

ReleasingH2molecules with a partial pressure difference without the use of temperature

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