Destruction of SO2 on Au and Cu Nanoparticles Dispersed on MgO(100) and CeO2(111)
When going from periodic surfaces to isolated clusters or nanoparticles, there is a big increase in the reactivity of Au and Cu toward SO{sub 2}. Density functional calculations indicate that the enhancement in the SO{sub 2} adsorption energy is due to the presence of corner sites (i.e., metal atoms with a low coordination number) and the fluxionality of the nanoparticles. Therefore, small Au particles bind SO{sub 2} stronger than a periodic Au(100) surface. However, the S {leftrightarrow} Au and O {leftrightarrow} Au interactions are not strong enough to induce the rupture of the S-O bonds. In contrast, the dissociation of SO{sub 2} on Cu particles is a very exothermic process, even more exothermic than on a periodic Cu(100) surface. Experiments of synchrotron-based high-resolution photoemission and X-ray absorption spectroscopy show big differences in the DeSOx activity of Au and Cu nanoparticles dispersed on MgO(100) and CeO{sub 2}(111). The heat of adsorption of the SO{sub 2} on Au nanoparticles supported on MgO(100) or CeO{sub 2}(111) was 0.2 to 0.4 eV larger than on Au(100) with negligible dissociation of the molecule. The full decomposition of SO{sub 2} was observed only after O vacancies were introduced in the ceria support. The O vacancies in ceria either played a direct role in the dissociation of SO{sub 2} (cracking of the molecule at the oxide-metal interface) or enhanced the chemical activity of the supported Au nanoparticles. The addition of Cu particles to MgO(100) or CeO{sub 2}(111) generates systems that are extremely active for the destruction of SO{sub 2}. At 100-150 K, the SO{sub 2} adsorbs molecularly on the supported Cu particles. Heating to temperatures above 200 K leads to massive dissociation of the SO{sub 2}. A comparison of the behavior of SO{sub 2} on Cu/MgO(100) and Cu/CeO{sub 2-x}(111) shows how important the reducibility of the oxide support in DeSOx operations can be.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1019945
- Report Number(s):
- BNL--95791-2011-JA
- Journal Information:
- Journal of Physical Chemistry A, Journal Name: Journal of Physical Chemistry A Journal Issue: 11 Vol. 114; ISSN 1089-5639
- Country of Publication:
- United States
- Language:
- English
Similar Records
Gold Nanoparticles on Ceria: Importance of O Vacancies in the Activation of Gold
Water Dissociation on CeO2(100) and CeO2(111) Thin Films