Charge transfer as a ubiquitous mechanism in determining the negative charge at hydrophobic interfaces

@article{Poli2020ChargeTA,
  title={Charge transfer as a ubiquitous mechanism in determining the negative charge at hydrophobic interfaces},
  author={Emiliano Poli and Kwang Hyok Jong and Ali A Hassanali},
  journal={Nature Communications},
  year={2020},
  volume={11}
}
The origin of the apparent negative charge at hydrophobic–water interfaces has fueled debates in the physical chemistry community for decades. The most common interpretation given to explain this observation is that negatively charged hydroxide ions (OH – ) bind strongly to the interfaces. Using first principles calculations of extended air–water and oil–water interfaces, we unravel a mechanism that does not require the presence of OH – . Small amounts of charge transfer along hydrogen bonds… Expand
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References

SHOWING 1-10 OF 102 REFERENCES
An explanation for the charge on water's surface.
TLDR
A Hamaker-like force on the hydroxide ion is shown that attracts it to regions where dipole-moment fluctuations are smaller than in bulk water, in other words, to regions of low relative permittivity. Expand
Orientation-Induced Adsorption of Hydrated Protons at the Air-Water Interface.
TLDR
This work calculates surface tensions and ionic surface propensities at air-water interfaces from classical, thermodynamically consistent molecular dynamics simulations and concludes that NaOH, HCl, and NaCl solutions show outstanding quantitative agreement with experiment. Expand
The excess proton at the air-water interface: The role of instantaneous liquid interfaces.
TLDR
Using ab initio molecular dynamics simulations, this work revisits the propensity of the excess proton for the air-water interface with a particular focus on the role of instantaneous liquid interfaces and finds a more pronounced presence for the proton to be at the air -water interface. Expand
Charge Transfer between Water Molecules As the Possible Origin of the Observed Charging at the Surface of Pure Water
Classical molecular dynamics simulations point to an anisotropy of water–water hydrogen bonding at the water surface. Approaching from the gas phase, a region of primarily dangling hydrogens isExpand
Charge transfer effects of ions at the liquid water/vapor interface.
TLDR
The effect of CT on ion adsorption to the water liquid-vapor interface is examined and CT is seen to have only minor effects on the overall free energy profiles, however, the long-ranged effects of ions are highlighted by the CT model. Expand
Propensity of Hydrated Excess Protons and Hydroxide Anions for the Air-Water Interface.
TLDR
New and statistically conclusive molecular-scale results on the affinity of the hydrated excess proton and hydroxide anion for the air-water interface are presented and the fluctuation in the coordination number around water sheds new light on the observed entropic trends for both ions. Expand
Exploring the behaviour of the hydrated excess proton at hydrophobic interfaces.
TLDR
The application of energy decomposition schemes to multiconfigurational simulations and the resulting consequences realized for the excess proton at hydrophobic interfaces are discussed. Expand
Central Role of Bicarbonate Anions in Charging Water/Hydrophobic Interfaces.
TLDR
This work reports on two series of independent experimental studies that demonstrate that in the pH 5-10 range the negative interfacial charge of the colloids mostly stems from bicarbonate ions, whereas at lower and higher pH, protons and hydroxide ions contribute to the interfacial charging. Expand
Hydrated proton and hydroxide charge transfer at the liquid/vapor interface of water.
TLDR
The hydrated proton and hydroxide affect water's liquid/vapor interface in a manner similar to monatomic ions, in that they induce a hydrogen-bonding imbalance at the surface, which results in charged surface waters, which persists until the ion is at least 10 Å away from the interface. Expand
Brønsted basicity of the air–water interface
TLDR
By detecting RCOO−, experiments show the presence of OH− on the aerial side of on pH > 2 water exposed to RCOOH(g), and infer that the outer surface of water is Brønsted neutral at pH ∼3 (rather than at pH 7 as bulk water), a value that matches the isoelectric point of bubbles and oil droplets in independent electrophoretic experiments. Expand
...
1
2
3
4
5
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