Surface Characterization of Colloidal Silica Nanoparticles by Second Harmonic Scattering: Quantifying the Surface Potential and Interfacial Water Order

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60076658%3A12310%2F19%3A43899381" target="_blank" >RIV/60076658:12310/19:43899381 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.9b05482" target="_blank" >https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.9b05482</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpcc.9b05482" target="_blank" >10.1021/acs.jpcc.9b05482</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Surface Characterization of Colloidal Silica Nanoparticles by Second Harmonic Scattering: Quantifying the Surface Potential and Interfacial Water Order

Popis výsledku v původním jazyce

The microscopic description of the interface of colloidal particles in solution is essential to understand and predict the stability of these systems, as well as their chemical and electrochemical reactivity. However, this description often relies on the use of simplified electrostatic mean field models for the structure of the interface, which give only theoretical estimates of surface potential values and do not provide properties related to the local microscopic structure, such as the orientation of interfacial water molecules. Here we apply polarimetric angle-resolved second harmonic scattering (AR-SHS) to 300 nm diameter SiO2 colloidal suspensions to experimentally determine both surface potential and interfacial water orientation as a function of pH and NaCl concentration. The surface potential values and interfacial water orientation change significantly over the studied pH and salt concentration range, whereas zeta-potential (zeta) values remain constant. By comparing the surface and zeta-potentials, we find a layer of hydrated condensed ions present in the high pH case, and for NaCl concentrations &gt;= 1 mM. For milder pH ranges (pH &lt; 11), as well as for salt concentrations &lt;1 mM, no charge condensation layer is observed. These findings are used to compute the surface charge densities using the Gouy-Chapman and Gouy-Chapman-Stern models. Furthermore, by using the AR-SHS data, we are able to determine the preferred water orientation in the layer directly in contact with the silica interface. Molecular dynamics simulations confirm the experimental trends and allow deciphering of the contributions of water layers to the total response.

Název v anglickém jazyce

Surface Characterization of Colloidal Silica Nanoparticles by Second Harmonic Scattering: Quantifying the Surface Potential and Interfacial Water Order

Popis výsledku anglicky

The microscopic description of the interface of colloidal particles in solution is essential to understand and predict the stability of these systems, as well as their chemical and electrochemical reactivity. However, this description often relies on the use of simplified electrostatic mean field models for the structure of the interface, which give only theoretical estimates of surface potential values and do not provide properties related to the local microscopic structure, such as the orientation of interfacial water molecules. Here we apply polarimetric angle-resolved second harmonic scattering (AR-SHS) to 300 nm diameter SiO2 colloidal suspensions to experimentally determine both surface potential and interfacial water orientation as a function of pH and NaCl concentration. The surface potential values and interfacial water orientation change significantly over the studied pH and salt concentration range, whereas zeta-potential (zeta) values remain constant. By comparing the surface and zeta-potentials, we find a layer of hydrated condensed ions present in the high pH case, and for NaCl concentrations &gt;= 1 mM. For milder pH ranges (pH &lt; 11), as well as for salt concentrations &lt;1 mM, no charge condensation layer is observed. These findings are used to compute the surface charge densities using the Gouy-Chapman and Gouy-Chapman-Stern models. Furthermore, by using the AR-SHS data, we are able to determine the preferred water orientation in the layer directly in contact with the silica interface. Molecular dynamics simulations confirm the experimental trends and allow deciphering of the contributions of water layers to the total response.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

<a href="/cs/project/GA17-10734S" target="_blank" >GA17-10734S: Molekulární popis jevů v elektrické dvojvrstvě - predikce a interpretace experimentálních dat počítačovými simulacemi</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Physical Chemistry C

ISSN

1932-7447

e-ISSN

—

Svazek periodika

123

Číslo periodika v rámci svazku

33

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

20393-20404

Kód UT WoS článku

000482545700036

EID výsledku v databázi Scopus

2-s2.0-85071680594