Insights from the Adsorption of Halide Ions on Graphene Materials

Zhu, Chang; Yang, Gang

doi:10.1002/cphc.201600271

Cited by 25 publications

(22 citation statements)

References 43 publications

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“…at the BLYP/LANL2DZ level. For Cl − , we found that the interaction energies obtained in our work were smaller than the previous results ,. This is probably attributed to the larger cluster size (C 150 H 30 ) adopted in our computation.…”

Section: Resultscontrasting

confidence: 78%

“…have proved that anion‐graphene interactions are unexpectedly strong and they attributed this phenomenon to the strong electron‐accepting ability of the unoccupied π*‐orbital. Zhu et al . showed that halide ions can remain stable on graphene surface, because the graphene acts as an acceptor by accepting the electron from halide ions.…”

Section: Introductionmentioning

confidence: 99%

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Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface

Chen

Yang

2018

ChemPhysChem

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The adsorption of ions on a graphene surface is very important to control relevant graphene-based processes. In this work, a multiscale simulation was carried out to study the adsorption of Na /Cl ions on graphene by combining quantum mechanics calculations and molecular dynamics (MD) simulations. The interaction energies of the ions with graphene were computed using density functional theory (DFT). It was found that the ions show strong interaction with a graphene cluster and the overwhelming portion of the interaction energy is the ion-π orbital interaction. The large orbital interaction can be ascribed to the two contributions arising from the ion-induced polarization of graphene and the charge transfer between ion and graphene. Their different contribution degrees reveal that the polarization effect plays a main role on the orbital interaction for ion adsorption. Comparatively, for Na/Cl atom adsorption, the charge transfer shows large part to the orbital interaction with weak atom-induced polarization. The obtained interaction energies were applied to develop new interaction potentials between ion and graphene, and then MD simulations were used to study the interfacial adsorption behavior of Na /Cl aqueous solution onto the graphene surface. Due to enhanced ion-π interactions, Na /Cl cooperatively demonstrates a strong ion adsorption layer through direct contact with the hydrophobic graphene surface. Our simulation result presents a new understanding of ion-graphene interactions.

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Section: Resultscontrasting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface

Chen

Yang

2018

ChemPhysChem

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“…We have found that our results are surprisingly insensitive to varying the flexibility of graphene but that ΔΔG ads does depend on the choice of interaction strength between the ion and the graphene. We have chosen this interaction to reproduce the experimental free energy difference, which yields an adsorption energy for iodide at graphene in vacuum (no waters) in reasonable agreement with density functional theory (21,22). This is similar in spirit to the approach of Williams et al (23), who capture the effects of the graphene-ion polarization interaction (as measured by density functional theory calculations) by empirically adjusting the interaction strength between the ion and the carbon atoms.…”

Section: Significancementioning

confidence: 87%

Mechanism of ion adsorption to aqueous interfaces: Graphene/water vs. air/water

McCaffrey

Nguyen

Cox

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The adsorption of ions to aqueous interfaces is a phenomenon that profoundly influences vital processes in many areas of science, including biology, atmospheric chemistry, electrical energy storage, and water process engineering. Although classical electrostatics theory predicts that ions are repelled from water/hydrophobe (e.g., air/water) interfaces, both computer simulations and experiments have shown that chaotropic ions actually exhibit enhanced concentrations at the air/water interface. Although mechanistic pictures have been developed to explain this counterintuitive observation, their general applicability, particularly in the presence of material substrates, remains unclear. Here we investigate ion adsorption to the model interface formed by water and graphene. Deep UV second harmonic generation measurements of the SCN − ion, a prototypical chaotrope, determined a free energy of adsorption within error of that for air/water. Unlike for the air/water interface, wherein repartitioning of the solvent energy drives ion adsorption, our computer simulations reveal that direct ion/graphene interactions dominate the favorable enthalpy change. Moreover, the graphene sheets dampen capillary waves such that rotational anisotropy of the solute, if present, is the dominant entropy contribution, in contrast to the air/water interface.specific ion effects | graphene | SHG spectroscopy | molecular dynamics | adsorption O ver a decade ago, detailed simulations predicted that certain simple ions would exhibit enhanced concentrations at the air/water interface (1), reinvigorating a century-old debate primarily addressing the origin of the famous Hofmeister effects in protein chemistry (2). Experiments subsequently verified these predictions (3, 4). Surface enhancement of simple ions has since been widely studied [e.g., see the review by Jungwirth and Tobias (5)] and attributed to various properties of the ions including size, polarizability, dispersion forces, hydration free energy (6-8), and the degree of interfacial roughness (9-11). Previous temperaturedependent deep UV (DUV) second harmonic generation (SHG) experiments from the Saykally group have determined the enthalpic and entropic contributions to the adsorption of the prototypical pseudohalide, the thiocyanate (SCN − ) ion, showing that a negative enthalpy change drives the ion adsorption, whereas a negative entropy change impedes it (9). Using molecular simulations performed in the same study, the following underlying mechanism was proposed: first, when the ion moves from the bulk to the interface, weakly interacting water molecules are displaced from both the surface and the ion solvent shell into the bulk solution, where they form stronger water-water bonds, leading to the negative enthalpy change. Second, the presence of an ion at the interface dampens its capillary wave fluctuations, leading to the negative entropy change. Although a consensus has yet to be reached regarding the complete theory of interfacial ion adsorption, these collective, detailed studie...

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“…Biochar, produced by the pyrolysis of biomass, has proven to be effective to improve soil properties, remediate soils with heave metal and organic pollutants and increase crop biomass [19]. With use of density functional calculations, we have demonstrated that biochar is potential to remediate soils with anionic pollutants [20], in addition to heavy metal ions that are known to us all.…”

Section: Introductionmentioning

confidence: 99%

“…Zhu et al [20] and Shi et al [59] clearly show that halide ions are potentially adsorbed on graphene, where halide ions are electron donors while graphene turn to be electron acceptors. Zhu et al [20] demonstrate the binding strengths of metal ions on pristine graphene are stronger than the halide ion when they are adsorbed; however, the edgefluorination alters the adsorption priority of metal ions versus halide ions and the adsorption strengths of metal ions/anions change in direct/reverse proportion with increase in functionalization degrees. In consequence, the preferential adsorption and selective removal of certain metal ions or anions can be facilely realized by choice of an appropriate functionalization degree.…”

Section: +mentioning

confidence: 99%

Adsorption of Ions at the Interface of Clay Minerals and Aqueous Solutions

Jia¹,

Wang²,

Zhu³

et al. 2016

Advances in Colloid Science

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Adsorption of ions at the interface of clay minerals and aqueous solutions plays a critical role in a wide spectrum of colloidal, chemical, physical, and geological processes. Owing to the particular complexity of related systems and the femtosecond scale of related processes, the direct experimental observations often become a challenging task. As a contrast, computer simulations have proven to be a competent and powerful approach therein and already realized fruitful and significant contributions. In this chapter, we attempt to draw a relatively comprehensive picture of the interfacial adsorption of ions mainly within the context of computer simulations. As elaborated, quantum mechanics (QM) and molecular dynamics (MD), two popular simulation techniques currently used, have respective advantages, and with their collaborative efforts, we are striding toward the in-depth and systematic understanding of adsorption configuration, distribution, stability, reaction thermodynamics and mechanism, dynamics, diffusivity as well as electric double layer and other fundamental issues that are closely associated with the adsorption of ions at the interface of clay minerals and aqueous solutions. In addition, we demonstrate that investigation of the interfacial adsorption of ions greatly helps to unravel the origin and mechanism of ion-specific effects, whose importance has been explicitly suggested to be no less than Gregor Mendel's work to genetics.

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Insights from the Adsorption of Halide Ions on Graphene Materials

Cited by 25 publications

References 43 publications

Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface

Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface

Mechanism of ion adsorption to aqueous interfaces: Graphene/water vs. air/water

Adsorption of Ions at the Interface of Clay Minerals and Aqueous Solutions

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