Separating the pH-Dependent Behavior of Water in the Stern and Diffuse Layers with Varying Salt Concentration
| dc.contributor.author | Darlington, Akemi M. | |
| dc.contributor.author | Jarisz, Tasha A. | |
| dc.contributor.author | DeWalt-Kerian, Emma L. | |
| dc.contributor.author | Roy, Sandra | |
| dc.contributor.author | Kim, Sun | |
| dc.contributor.author | Azam, Md. Shafiul | |
| dc.contributor.author | Hore, Dennis K. | |
| dc.contributor.author | Gibbs, Julianne M. | |
| dc.date.accessioned | 2019-12-23T23:37:37Z | |
| dc.date.available | 2019-12-23T23:37:37Z | |
| dc.date.copyright | 2017 | en_US |
| dc.date.issued | 2017 | |
| dc.description.abstract | Vibrational sum frequency generation (SFG) spectroscopy was utilized to distinguish different populations of water molecules within the electric double layer (EDL) at the silica/water interface. By systematically varying the electrolyte concentration, surface deprotonation, and SFG polarization combinations, we provide evidence of two regions of water molecules that have distinct pH-dependent behavior when the Stern layer is present (with onset between 10 and 100 mM NaCl). For example, water molecules near the surface in the Stern layer can be probed by the pss polarization combination, while other polarization combinations (ssp and ppp) predominantly probe water molecules further from the surface in the diffuse part of the electrical double layer. For the water molecules adjacent to the surface within the Stern layer, upon increasing the pH from the point-of-zero charge of silica (pH ∼2) to higher values (pH ∼12), we observe an increase in alignment consistent with a more negative surface with increasing pH. In contrast, water molecules further from the surface appear to exhibit a net flip in orientation upon increasing the pH over the same range, which we attribute to the presence of the Stern layer and possible overcharging of the EDL at lower pH. The opposing pH-dependent behavior of water in these two regions sheds new light on our understanding of the water structure within the EDL at high salt concentrations when the Stern layer is present. | en_US |
| dc.description.reviewstatus | Reviewed | en_US |
| dc.description.scholarlevel | Faculty | en_US |
| dc.description.sponsorship | J.M.G. acknowledges the Institute of Oil Sands Innovation (IOSI 2012-06), Petro Canada for a Young Innovator Award and the Sloan Foundation. J.M.G. and D.K.H. acknowledge Natural Science and Engineering Research Centre Discovery Grant. A.M.D. acknowledges an Alberta Innovates Technology Futures graduate fellowship. S.K. acknowledges Alberta/Technical University of Munich International Graduate School for Hybrid Functional Materials (ATUMS). We gratefully acknowledge helpful discussions with Dr. Matthew Brown (ETH), Prof. Eric Tyrode (KTH), and Prof. Hongfei Wang (PNNL). | en_US |
| dc.identifier.citation | Darlington, A. M.; Jarisz, T. A.; DWalt-Kerian, E. L.; Roy, S.; Kim, S.; Azam, M. S.; Hore, D. K.; & Gibbs, J. M. (2017). Separating the pH-dependent behavior of water in the Stern and diffuse layers with varying salt concentration. The Journal of Physical Chemistry C, 121(37), 20229-20241. DOI: 10.1021/acs.jpcc.7b03522 | en_US |
| dc.identifier.uri | https://doi.org/10.1021/acs.jpcc.7b03522 | |
| dc.identifier.uri | http://hdl.handle.net/1828/11415 | |
| dc.language.iso | en | en_US |
| dc.publisher | The Journal of Physical Chemistry C | en_US |
| dc.subject | Interfaces | |
| dc.subject.department | Department of Chemistry | |
| dc.title | Separating the pH-Dependent Behavior of Water in the Stern and Diffuse Layers with Varying Salt Concentration | en_US |
| dc.type | Postprint | en_US |