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Bimodal Acidity at the Amorphous Silica/Water Interface
- Source :
- Journal of Physical Chemistry C, Journal of Physical Chemistry C, 2015, 119 (49), pp.27354-27362. ⟨10.1021/acs.jpcc.5b02854⟩, Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (49), pp.27354-27362. ⟨10.1021/acs.jpcc.5b02854⟩
- Publication Year :
- 2015
- Publisher :
- HAL CCSD, 2015.
-
Abstract
- International audience; Understanding the microscopic origin of the acid base behavior of mineral surfaces in contact with water is still a challenging task, for both the experimental and the theoretical communities. Even for a relatively simple material, such as silica, the origin of the bimodal acidity behavior is still a debated topic. In this contribution we calculate the acidity of single sites on the humid silica surface represented by a model for the hydroxylated amorphous surface. Using a thermodynamic integration approach based on ab initio molecular dynamics, we identify two different acidity values. In particular, some convex geminals and some type of vicinals are very acidic (pKa = 2.9 and 2.1, respectively) thanks to a special stabilization of their deprotonated forms. This recalls the behavior of the out-of-plane silanols on the crystalline (0001) alpha-quartz surface, although the acidity here is even stronger. On the contrary, the concave geminals and the isolated groups present a quite high pKa (8.9 and 10.3, respectively), similar to the one of silicic acid in liquid water.
- Subjects :
- Siloxanes
Chemistry
Acidity
Interfaces
Thermodynamic integration
Silica
02 engineering and technology
[CHIM.MATE]Chemical Sciences/Material chemistry
Noncovalent
interactions
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
0104 chemical sciences
Surfaces, Coatings and Films
Electronic, Optical and Magnetic Materials
Amorphous solid
Ab initio molecular dynamics
General Energy
Deprotonation
Computational chemistry
Chemical physics
Physical and Theoretical Chemistry
Amorphous silica
0210 nano-technology
Subjects
Details
- Language :
- English
- ISSN :
- 19327447 and 19327455
- Database :
- OpenAIRE
- Journal :
- Journal of Physical Chemistry C, Journal of Physical Chemistry C, 2015, 119 (49), pp.27354-27362. ⟨10.1021/acs.jpcc.5b02854⟩, Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (49), pp.27354-27362. ⟨10.1021/acs.jpcc.5b02854⟩
- Accession number :
- edsair.doi.dedup.....a8422b929d1a3d601020f214c7d94f21