Using a density functional theory approach with dispersion corrections, we have studied the adsorption properties of Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au monomers and dimers on the hydroxylated surface of alpha-quartz. We also considered the interaction with Si-O-center dot paramagnetic centers (NBO centers) or with silanols ( Si-O-H) to form a Si-O-TMx (x = 1, 2) group and a 1/2 H-2 molecule. On the hydroxylated surface, the TM atoms bind relatively weakly, while strong adsorption energies of 4-5 eV are found on the NBO center where due to the coupling of the unpaired electron of the Si-O-center dot unit and the valence states of the metal atom. The TM atoms can react with the silanol groups releasing H-2 and forming a stable Si-O-TM complex with exothermic reactions. Dimers arriving from the gas-phase interact with the hydroxylated quartz surface with energies between 0.5 and 1.4 eV. If two TM atoms diffusing on the surface form a dimer, they release a large amount of energy which largely exceeds the dimer adsorption energy, leading to possible dimer desorption (with the exception of Pd). Also dimers bind strongly to NBO centers. Here the dimerization energies are considerably smaller than the desorption energy showing that the NBO sites act as effective nucleation centers. Differently from TM atoms, only some of the dimers react with Si-O-H groups.

Schlexer, P., Pacchioni, G. (2017). Adsorption and Dimerization of Late Transition Metal Atoms on the Regular and Defective Quartz (001) Surface. TOPICS IN CATALYSIS, 60(6-7), 459-470 [10.1007/s11244-016-0712-x].

Adsorption and Dimerization of Late Transition Metal Atoms on the Regular and Defective Quartz (001) Surface

SCHLEXER, PHILOMENA DENIZ
Primo
;
PACCHIONI, GIANFRANCO
Ultimo
2017

Abstract

Using a density functional theory approach with dispersion corrections, we have studied the adsorption properties of Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au monomers and dimers on the hydroxylated surface of alpha-quartz. We also considered the interaction with Si-O-center dot paramagnetic centers (NBO centers) or with silanols ( Si-O-H) to form a Si-O-TMx (x = 1, 2) group and a 1/2 H-2 molecule. On the hydroxylated surface, the TM atoms bind relatively weakly, while strong adsorption energies of 4-5 eV are found on the NBO center where due to the coupling of the unpaired electron of the Si-O-center dot unit and the valence states of the metal atom. The TM atoms can react with the silanol groups releasing H-2 and forming a stable Si-O-TM complex with exothermic reactions. Dimers arriving from the gas-phase interact with the hydroxylated quartz surface with energies between 0.5 and 1.4 eV. If two TM atoms diffusing on the surface form a dimer, they release a large amount of energy which largely exceeds the dimer adsorption energy, leading to possible dimer desorption (with the exception of Pd). Also dimers bind strongly to NBO centers. Here the dimerization energies are considerably smaller than the desorption energy showing that the NBO sites act as effective nucleation centers. Differently from TM atoms, only some of the dimers react with Si-O-H groups.
Articolo in rivista - Articolo scientifico
SiO2; Quartz surface; Metal atoms; Nucleation; Density functional theory
English
459
470
12
Schlexer, P., Pacchioni, G. (2017). Adsorption and Dimerization of Late Transition Metal Atoms on the Regular and Defective Quartz (001) Surface. TOPICS IN CATALYSIS, 60(6-7), 459-470 [10.1007/s11244-016-0712-x].
Schlexer, P; Pacchioni, G
File in questo prodotto:
File Dimensione Formato  
2016_3.pdf

Solo gestori archivio

Dimensione 4.46 MB
Formato Adobe PDF
4.46 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/140464
Citazioni
  • Scopus 11
  • ???jsp.display-item.citation.isi??? 11
Social impact