The University of Southampton
University of Southampton Institutional Repository

Acid-base dissociation mechanisms at the silica-water interface: A DFT study

Acid-base dissociation mechanisms at the silica-water interface: A DFT study
Acid-base dissociation mechanisms at the silica-water interface: A DFT study
One of the fundamental effects of the hydration of silica surfaces is the production of surface charges. This phenomenon is believed to be primarily a consequence of proton uptake and release at the silica/water interface [1]. Hydrated silica surfaces have been the focus of much experimental and simulation work due to their importance in nanodevices such as Ion-Sensitive Field Effect Transistors (IS-FETs) [2], however the electrostatics and dynamics of these surfaces are not well understood. For example, there is still no consensus on whether the partial charge or unit charge model is more representative of the underlying charging mechanism [3].

In this work, Density Functional Theory (DFT) calculations are used to investigate the fundamental protonation/deprotonation reactions at the silica/water interface. The silica surface was modelled as a periodic slab, whereas the solvent was modeled as a hydrated cluster containing hydronium or hydroxide ions. These reactions were found to be highly exothermic and activationless, and showed a rate of reaction limited by reorientation of the nearby water molecules. A new mechanism of surface protonation was demonstrated where hydronium ions protonate the surface without transfer of their protons to the surface, this occurred via stabilising the dissociation of intermediate water molecules. Understanding these kinetics is vital to interpreting signal-to-noise characteristics of chemically sensitive nanodevices such as nano-IS-FETs. [4]
Lowe, Benjamin
69b560bf-d230-4b2a-b103-8e2b485c58a7
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61
Green, Nicolas
d9b47269-c426-41fd-a41d-5f4579faa581
Lowe, Benjamin
69b560bf-d230-4b2a-b103-8e2b485c58a7
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61
Green, Nicolas
d9b47269-c426-41fd-a41d-5f4579faa581

Lowe, Benjamin, Skylaris, Chris-Kriton and Green, Nicolas (2016) Acid-base dissociation mechanisms at the silica-water interface: A DFT study. 251st American Chemical Society National Meeting & Exposition - Computers in Chemistry, San Diego, United States. 13 - 17 Mar 2016.

Record type: Conference or Workshop Item (Paper)

Abstract

One of the fundamental effects of the hydration of silica surfaces is the production of surface charges. This phenomenon is believed to be primarily a consequence of proton uptake and release at the silica/water interface [1]. Hydrated silica surfaces have been the focus of much experimental and simulation work due to their importance in nanodevices such as Ion-Sensitive Field Effect Transistors (IS-FETs) [2], however the electrostatics and dynamics of these surfaces are not well understood. For example, there is still no consensus on whether the partial charge or unit charge model is more representative of the underlying charging mechanism [3].

In this work, Density Functional Theory (DFT) calculations are used to investigate the fundamental protonation/deprotonation reactions at the silica/water interface. The silica surface was modelled as a periodic slab, whereas the solvent was modeled as a hydrated cluster containing hydronium or hydroxide ions. These reactions were found to be highly exothermic and activationless, and showed a rate of reaction limited by reorientation of the nearby water molecules. A new mechanism of surface protonation was demonstrated where hydronium ions protonate the surface without transfer of their protons to the surface, this occurred via stabilising the dissociation of intermediate water molecules. Understanding these kinetics is vital to interpreting signal-to-noise characteristics of chemically sensitive nanodevices such as nano-IS-FETs. [4]

Full text not available from this repository.

More information

Published date: March 2016
Venue - Dates: 251st American Chemical Society National Meeting & Exposition - Computers in Chemistry, San Diego, United States, 2016-03-13 - 2016-03-17

Identifiers

Local EPrints ID: 417249
URI: http://eprints.soton.ac.uk/id/eprint/417249
PURE UUID: 27b07310-5b4b-47f5-ad14-5287ee5635bd
ORCID for Chris-Kriton Skylaris: ORCID iD orcid.org/0000-0003-0258-3433
ORCID for Nicolas Green: ORCID iD orcid.org/0000-0001-9230-4455

Catalogue record

Date deposited: 26 Jan 2018 17:30
Last modified: 30 Jan 2020 01:34

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×