Confined fluids in mesoporous silica systems: a DFT approach
Dr. Ignacio Chevallier-Boutell
(National University of Cordoba)

Confining liquids in a mesoporous material may change observable properties such as spin relaxation and effective diffusion. These quantities are very useful to characterise the morphology of the porous system, and also help to understand molecular transport inside the material.
Bearing this in mind, the main aim of my PhD thesis is to study the behaviour of confined fluids in mesoporous silica structures, combining and correlating experimental and theoretical approaches through Nuclear Magnetic Resonance (NMR) and Density Functional Theory (DFT). In this seminar, I will share some of my DFT results.
On the one hand, I will focus on the interaction between alkanes and silica surfaces. We have shown with ab initio calculations that these interactions are non-negligible [1], contrary to the assumptions reported in previous works [2]. We have also established the dependence of the adsorption energy with the molecular length and shape, with the coverage degree, and with confinement. Some of these ideas are sketched in the next figure:

On the other hand, we have put the spotlight on studying the structuring of water on the same substrate, performing ab initio molecular dynamics calculations involving several water molecules on a silica surface. Preliminar results show strong water-silica interaction and long range structuring.

References:
[1] Chevallier-Boutell IJ et al., Microporous and Mesoporous Mater., 2021, 326, 111315.
[2] D’Agostino C. et al., Phys. Chem. C, 2012, 116 (16) 8975-8982.