Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081707%3A_____%2F17%3A00485594" target="_blank" >RIV/68081707:_____/17:00485594 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1039/c7cp03663a" target="_blank" >http://dx.doi.org/10.1039/c7cp03663a</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/c7cp03663a" target="_blank" >10.1039/c7cp03663a</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts

Popis výsledku v původním jazyce

We report on a series of ab initio molecular dynamics investigations on LiCl, NaCl, and KCl aqueous solutions under the effect of static electric fields. We have found that although in low-to-moderate field intensity regimes the well-known sequence of cationic mobilities mu(K+) > mu(Na+) > mu(Li+) (i.e., the bigger the cation the higher the mobility) is recovered, from intense field strengths this intuitive rule is no longer verified. In fact, field-induced water molecular dissociations lead to more complex phenomena regulating the standard migration properties of the simplest monovalent cations. The water dissociation threshold is lowered from 0.35 V angstrom(-1) to 0.25 V angstrom(-1) by the presence of charged species in all samples. However, notwithstanding a one-stage process of water ionization and proton conduction takes place at 0.25 V angstrom(-1) in the electrolyte solutions where structure maker' cations are present (i.e., LiCl and NaCl), the KCl aqueous solution shows some hindrance in establishing a proton conductive regime, which is characterized by the same proton conduction threshold of neat water (i.e., 0.35 V angstrom(-1)). In addition, it turns out that protons flow easily in the LiCl (sp = 3.0 S cm(-1)) solution and then in descending order in the NaCl (sp = 2.5 S cm(-1)) and KCl (sp = 2.3 S cm(-1)) electrolyte solutions. The protonic conduction efficiency is thus inversely proportional to the ionic radii of the cations present in the samples. Moreover, Cl- anions act as a sort of protonic well for high field intensities, further lowering the overall proton transfer efficiency of the aqueous solutions. As a consequence, all the recorded protonic conductivities are lower than that for neat water (sp = 7.8 S cm(-1)), which strongly indicates that devices exploiting the proton transfer ability should be designed so as to minimize the presence of ionic impurities.

Název v anglickém jazyce

Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts

Popis výsledku anglicky

We report on a series of ab initio molecular dynamics investigations on LiCl, NaCl, and KCl aqueous solutions under the effect of static electric fields. We have found that although in low-to-moderate field intensity regimes the well-known sequence of cationic mobilities mu(K+) > mu(Na+) > mu(Li+) (i.e., the bigger the cation the higher the mobility) is recovered, from intense field strengths this intuitive rule is no longer verified. In fact, field-induced water molecular dissociations lead to more complex phenomena regulating the standard migration properties of the simplest monovalent cations. The water dissociation threshold is lowered from 0.35 V angstrom(-1) to 0.25 V angstrom(-1) by the presence of charged species in all samples. However, notwithstanding a one-stage process of water ionization and proton conduction takes place at 0.25 V angstrom(-1) in the electrolyte solutions where structure maker' cations are present (i.e., LiCl and NaCl), the KCl aqueous solution shows some hindrance in establishing a proton conductive regime, which is characterized by the same proton conduction threshold of neat water (i.e., 0.35 V angstrom(-1)). In addition, it turns out that protons flow easily in the LiCl (sp = 3.0 S cm(-1)) solution and then in descending order in the NaCl (sp = 2.5 S cm(-1)) and KCl (sp = 2.3 S cm(-1)) electrolyte solutions. The protonic conduction efficiency is thus inversely proportional to the ionic radii of the cations present in the samples. Moreover, Cl- anions act as a sort of protonic well for high field intensities, further lowering the overall proton transfer efficiency of the aqueous solutions. As a consequence, all the recorded protonic conductivities are lower than that for neat water (sp = 7.8 S cm(-1)), which strongly indicates that devices exploiting the proton transfer ability should be designed so as to minimize the presence of ionic impurities.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název periodika

Physical Chemistry Chemical Physics

ISSN

1463-9076

e-ISSN

—

Svazek periodika

19

Číslo periodika v rámci svazku

31

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

10

Strana od-do

20420-20429

Kód UT WoS článku

000407763700011

EID výsledku v databázi Scopus

—