Electrolyte interactions with colloidal gold nanoparticles in water
<p>Electrolyte interactions with colloidal nanoparticles (NPs) in aqueous solutions have been implicated in a wide range of research and applications. Existing studies on electrolyte interactions with NPs are primarily based on the electrical double layer (EDL) theory. However, the EDL model p...
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ndltd-MSSTATE-oai-library.msstate.edu-etd-04172017-1834452019-05-15T18:44:00Z Electrolyte interactions with colloidal gold nanoparticles in water Perera, H.A.Ganganath Sanjeewa Chemistry <p>Electrolyte interactions with colloidal nanoparticles (NPs) in aqueous solutions have been implicated in a wide range of research and applications. Existing studies on electrolyte interactions with NPs are primarily based on the electrical double layer (EDL) theory. However, the EDL model provides very limited information on how electrolytes directly bind to NPs, electrolyte impact on charge distribution on NPs, and NP morphological modification upon electrolyte binding. Furthermore, the previous reports have mainly focused on either cations or anions binding onto NPs, while the potential cation and anion coadsorption onto NPs and NP-facilitated cation-anion interactions remain largely uncharted. Filling these knowledge gaps are critical to enhance the fundamental understanding of interfacial interactions of electrolytes with NPs.</p> <p>Experimental characterization of cations and anions at the solid/liquid interface is a challenging analytical task. In the first study, we demonstrated the first direct experimental evidence of ion pairing on gold nanoparticles (AuNPs) in water by using surface enhanced Raman spectroscopy (SERS) in combination with electrolyte washing. Unlike ion pairing in aqueous solutions where the oppositely charged ions are either in direct contact or separated by a solvation shell, the ion pairing on AuNPs refers to cation and anion coadsorption onto the same NP surface regardless of separation distance. Ion pairing reduces the electrolyte threshold concentration in inducing AuNP aggregation and enhances the competitiveness of electrolyte over neutral molecules in binding to AuNPs.</p> <p>In the second study, we demonstrated that binding, structure, and properties of an ionic species on AuNPs are significantly dependent on the counterion adsorbed on AuNPs. These counterion effects include electrolyte-induced AuNP aggregation and fusion, quantitative cation and anion coadsorption on AuNPs, and SERS spectral distortion induced by the ionic species on AuNP surfaces.</p> <p>In the final study, we proposed that ion pairing as the main mechanism for reducing electrostatic repulsion among organothiolates self-assembled on AuNPs in water by using a series of experimental and computational studies. The work described in this dissertation provides a series of new insights into electrolyte interfacial interactions with AuNPs. </p> Stephen C. Foster Joseph P. Emerson Todd E. Mlsna David O. Wipf Dongmao Zhang MSSTATE 2017-07-31 text application/pdf http://sun.library.msstate.edu/ETD-db/theses/available/etd-04172017-183445/ http://sun.library.msstate.edu/ETD-db/theses/available/etd-04172017-183445/ en unrestricted I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, Dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Mississippi State University Libraries or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, Dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, Dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, Dissertation, or project report. |
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Chemistry Perera, H.A.Ganganath Sanjeewa Electrolyte interactions with colloidal gold nanoparticles in water |
description |
<p>Electrolyte interactions with colloidal nanoparticles (NPs) in aqueous solutions have been implicated in a wide range of research and applications. Existing studies on electrolyte interactions with NPs are primarily based on the electrical double layer (EDL) theory. However, the EDL model provides very limited information on how electrolytes directly bind to NPs, electrolyte impact on charge distribution on NPs, and NP morphological modification upon electrolyte binding. Furthermore, the previous reports have mainly focused on either cations or anions binding onto NPs, while the potential cation and anion coadsorption onto NPs and NP-facilitated cation-anion interactions remain largely uncharted. Filling these knowledge gaps are critical to enhance the fundamental understanding of interfacial interactions of electrolytes with NPs.</p>
<p>Experimental characterization of cations and anions at the solid/liquid interface is a challenging analytical task. In the first study, we demonstrated the first direct experimental evidence of ion pairing on gold nanoparticles (AuNPs) in water by using surface enhanced Raman spectroscopy (SERS) in combination with electrolyte washing. Unlike ion pairing in aqueous solutions where the oppositely charged ions are either in direct contact or separated by a solvation shell, the ion pairing on AuNPs refers to cation
and anion coadsorption onto the same NP surface regardless of separation distance. Ion pairing reduces the electrolyte threshold concentration in inducing AuNP aggregation and enhances the competitiveness of electrolyte over neutral molecules in binding to AuNPs.</p>
<p>In the second study, we demonstrated that binding, structure, and properties of an ionic species on AuNPs are significantly dependent on the counterion adsorbed on AuNPs. These counterion effects include electrolyte-induced AuNP aggregation and fusion, quantitative cation and anion coadsorption on AuNPs, and SERS spectral distortion induced by the ionic species on AuNP surfaces.</p>
<p>In the final study, we proposed that ion pairing as the main mechanism for reducing electrostatic repulsion among organothiolates self-assembled on AuNPs in water by using a series of experimental and computational studies. The work described in this dissertation provides a series of new insights into electrolyte interfacial interactions with AuNPs. </p> |
author2 |
Stephen C. Foster |
author_facet |
Stephen C. Foster Perera, H.A.Ganganath Sanjeewa |
author |
Perera, H.A.Ganganath Sanjeewa |
author_sort |
Perera, H.A.Ganganath Sanjeewa |
title |
Electrolyte interactions with colloidal gold nanoparticles in water |
title_short |
Electrolyte interactions with colloidal gold nanoparticles in water |
title_full |
Electrolyte interactions with colloidal gold nanoparticles in water |
title_fullStr |
Electrolyte interactions with colloidal gold nanoparticles in water |
title_full_unstemmed |
Electrolyte interactions with colloidal gold nanoparticles in water |
title_sort |
electrolyte interactions with colloidal gold nanoparticles in water |
publisher |
MSSTATE |
publishDate |
2017 |
url |
http://sun.library.msstate.edu/ETD-db/theses/available/etd-04172017-183445/ |
work_keys_str_mv |
AT pererahaganganathsanjeewa electrolyteinteractionswithcolloidalgoldnanoparticlesinwater |
_version_ |
1719086082432172032 |