Detecting underscreening and generalized Kirkwood transitions in aqueous electrolytes

The Journal of Chemical Physics, Год журнала: 2024, Номер 161(15)

Опубликована: Окт. 21, 2024

We establish the connection between measured small angle x-ray scattering signal and charge–charge correlations underlying Kirkwood transitions (KTs) in 1:1, 2:1, 3:1 aqueous electrolytes. These measurements allow us to obtain underscreening lengths for bulk electrolytes independently verified by theory simulations. Furthermore, we generalize concept of KTs beyond those theoretically predicted 1:1 electrolytes, which involves inverse screening length, a0, periodicity Q0. Above KTs, find a universal scaling a0∝c−ζ/3 Q0 ∝ c1/3 studied electrolyte solutions, where ζ is ionic strength factor.

Язык: Английский

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Cavity correlations and the onset of charge ordering at charged interfaces: A modified Poisson–Fermi approach

The Journal of Chemical Physics, Год журнала: 2025, Номер 162(3)

Опубликована: Янв. 15, 2025

Charge layering in the close vicinity of charged interfaces is a well-known effect, extensively reported both experiments and simulations Room Temperature Ionic Liquids (RTILs) concentrated electrolytes. The traditional Poisson-Fermi (PF) theory able to successfully describe overcrowding effects but fails reproduce charge ordering even strong coupling regimes. Simple models, yet capable investigating interplay between these important interfacial phenomena, are still lacking. In order bridge this gap, we herein present modified PF approach that capture regimes typical RTIL. modification based on introduction cavities around test-particles, which simply extend exclusion volume also incorporate accompanying depletion charges due particle insertion. addition simple ingredient shown overscreening ordering, thereby extending predictive power Using linear response theory, were study emergence two characteristic lengths: wavelength responsible for layering, along with damping length screens oscillations. At large ionic strengths couplings, system undergoes transition undamped layering. takes place when poles Fourier components potential become real-valued. This criterion allows one identify line across parameter space, thus delimiting region stability against unscreened ordering.

Язык: Английский

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Exceptionally Strong Double-Layer Barriers Generated by Polyampholyte Salt

The Journal of Physical Chemistry B, Год журнала: 2025, Номер unknown

Опубликована: Апрель 3, 2025

Experiments using the surface force apparatus have found anomalously long-range interactions between charged surfaces in concentrated salt solutions. Ion clustering has been suggested as a possible origin of this behavior. In work, we demonstrate that if such stable clusters indeed form, they are able to induce remarkably strong free energy barriers under conditions where corresponding solution simple provides negligible forces. Our cluster model is based on connected ions producing polyampholyte containing symmetric mixture monovalent cationic and anionic polyampholytes. distributions evaluated utilizing statistical-mechanical (classical) polymer density functional theory, cDFT. Supporting Information, briefly investigate range different architectures (connectivities), but main part ion modeled linear chain with alternating charges, which ends carry an identical charge (hence, net charge). These salts generate repulsions, similarly surfaces, remarkable strength, exceeding those from by orders magnitude. The underlying mechanism for formation brush-like layers at i.e., repulsion strongly related excluded volume effects, manner similar interaction carrying grafted polymers. We believe our results relevant not only mechanisms long-ranged underscreening solutions also potential use synthesized extremely efficient stabilizers colloidal dispersions.

Язык: Английский

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Dynamical correlation between ions in liquid seen in real space and time

Applied Physics Letters, Год журнала: 2025, Номер 126(16)

Опубликована: Апрель 21, 2025

Controlling ionic transport in liquids is anticipated to provide new scientific and technological opportunities, but it requires accurate knowledge of atomic-scale dynamics ions beyond the hydrodynamic description. Atomic characterized by strong dynamical correlations among atoms, which render a conventional approach describing reciprocal space challenging. We propose an alternative describe liquid real time using time-delayed two-body correlation function, Van Hove discuss recent results on local water electrolytes.

Язык: Английский

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Wave mechanics in an ionic liquid mixture

Faraday Discussions, Год журнала: 2024, Номер 253, С. 193 - 211

Опубликована: Янв. 1, 2024

Experimental measurements of interactions in ionic liquids and concentrated electrolytes over the past decade or so have revealed simultaneous monotonic oscillatory decay modes. These observations been hard to interpret using classical theories, which typically allow for just one electrostatic mode electrolytes. Meanwhile, substantial progress theoretical description dielectric response ion correlations has illuminated deep connection between density charge multiplicity modes characterising a liquid electrolyte. The challenge front us is build connections expressions pair correlation functions directly measured free energy interaction macroscopic surfaces experiments. Towards this aim, we here present analysis bodies across fluid mixture two widely diverging size. forces mixtures are significantly more complex than either pure liquids, but can be fitted superposition with parameters matching those liquids. We discuss empirical finding, hints at kind wave mechanics matter.

Язык: Английский

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Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes

The Journal of Physical Chemistry B, Год журнала: 2024, Номер 128(30), С. 7438 - 7444

Опубликована: Июль 22, 2024

Electrolytes are central to many technological applications, as well life itself. The behavior and properties of electrolytes often described in terms ion pairs, whereby ions associate either contact pairs (in which "touching") solvent-separated ions' solvent shells overlap) or solvent-solvent-separated distinct). However, this paradigm is generally restricted statistically averaged descriptions solution structure ignores temporal behavior. Here we elucidate the time-resolved dynamics these ion-ion interactions aqueous metal chloride using partial van Hove correlation function, based on polarizable molecular simulations. Our results show that existence persistence should not be assumed a priori, but fact specific features with lifetimes subpicosecond time scales.

Язык: Английский

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Beyond the Debye–Hückel limit: Toward a general theory for concentrated electrolytes

The Journal of Chemical Physics, Год журнала: 2024, Номер 161(23)

Опубликована: Дек. 16, 2024

The phenomenon of underscreening in concentrated electrolyte solutions leads to a larger decay length the charge-charge correlation than prediction Debye-Hückel (DH) theory and has found resurgence both theoretical experimental interest chemical physics community. To systematically understand investigate this electrolytes requires describe correlations beyond DH theory. We review theories that can transition from limit concentrations where charge dominate, giving rise associated Kirkwood Transitions (KTs). In perspective, we provide conceptual approach formulation exploits competition between molecular-informed short-range (SR) long-range interactions. demonstrate all deviations for real be expressed through single function ΣQ determined theoretically numerically. Importantly, directly related details SR interactions and, therefore, used as tool how differences representations interaction influence collective effects. precise form inferred Gaussian field number densities. resulting is validated by experiment accurately screening bulk electrolytes. predictions lengths appear less ∼1 nm at above KTs.

Язык: Английский

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Donnan equilibrium in charged slit-pores from a hybrid nonequilibrium molecular dynamics/Monte Carlo method with ions and solvent exchange

The Journal of Chemical Physics, Год журнала: 2024, Номер 161(5)

Опубликована: Авг. 1, 2024

Ion partitioning between different compartments (e.g., a porous material and bulk solution reservoir), known as Donnan equilibrium, plays fundamental role in various contexts such energy, environment, or water treatment. The linearized Poisson–Boltzmann (PB) equation, capturing the thermal motion of ions with mean-field electrostatic interactions, is practically useful to understand predict ion partitioning, despite its limited applicability conditions low salt concentrations surface charge densities. Here, we investigate equilibrium coarse-grained dilute electrolytes confined charged slit-pores reservoir solvent. We introduce use an extension systems recently developed hybrid nonequilibrium molecular dynamics/grand canonical Monte Carlo simulation method (“H4D”), which enhances efficiency solvent ion-pair exchange via fourth spatial dimension. show that validity range PB theory can be extended highly pores by simply considering renormalized compare simulations implicit models thin electric double layer limit considered here, explicit has effect on main limitations analytical predictions are not due breakdown description but rather renormalization approximation, because it only focuses behavior far from surfaces.

Язык: Английский

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Long-Range Surface Forces in Salt-in-Ionic Liquids

ACS Nano, Год журнала: 2024, Номер unknown

Опубликована: Дек. 6, 2024

Ionic liquids (ILs) are a promising class of electrolytes with unique combination properties, such as extremely low vapor pressures and nonflammability. Doping ILs alkali metal salts creates an electrolyte that is interest for battery technology. These salt-in-ionic (SiILs) superconcentrated, strongly correlated, asymmetric electrolytes. Notably, the transference numbers cations have been found to be negative. Here, we investigate Na-based SiILs surface force apparatus, X-ray scattering, atomic microscopy. We find evidence confinement-induced structural changes, giving rise long-range interactions. Force curves also reveal structure consistent our predictions from theory simulations. The steric interactions in reflect high aspect ratio compressible aggregates at interfaces rather than purely electrostatic origin predicted by classical theory. This conclusion supported reported anomalous negative numbers, which can explained within same aggregation framework. interfacial nanostructure should impact formation solid interphase SiILs.

Язык: Английский

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The Polarity of Co-solvents Regulates the Charge Storage Mechanisms in Supercapacitors with Concentrated Electrolytes

The Journal of Physical Chemistry Letters, Год журнала: 2024, Номер 15(34), С. 8903 - 8909

Опубликована: Авг. 22, 2024

Developing better energy storage devices depends on comprehending the underlying mechanisms involved in charge storage. With continuous conception of new electrolytes, this task becomes progressively more urgent and complex. An example is utilization co-solvated concentrated solutions. While these show promising electrochemical responses, their dynamic properties (especially under confinement) relationships with performance are not fully understood. Here, we combined modified step potential spectroscopy quasielastic neutron scattering to investigate systems composed activated mesoporous carbon (AMC) solutions lithium bis(trifluoromethanesulfonyl)imide acetonitrile either toluene or acetone. We report that acetone does impair surface-controlled mechanisms, contrary case toluene, which competes charged species populate AMC's pores without contributing In turn, promotes a greater overall capacitance owing Faradaic processes, may be related changes solvation structures confinement.

Язык: Английский

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