The most abundant liquid interface on earth, that of air and water, is believed to carry a negative potential that is non-trivial to invert through changes in pH, electrolyte, or electrolyte strength. Here, through a combined experimental and theoretical study, we show that the close approach of a negatively charged nanoparticle induces a charge redistribution of the air-water interface. Using different electrolytes to control the interfacial potential of the nanoparticles, in situ X-ray photoelectron spectroscopy results establish that nanoparticles with a more negative zeta potential adsorb closer to the air-water interface than do the same particles with less negative zeta potential. The attractive force between two (nominally) negative surfaces is caused solely because of a charge redistribution of the air-water interface under the strong electric field of the nanoparticle. This induced positive charge density will subsequently influence, and could be used to control reactivity, stability and nanoparticle self-assembly at air-water interfaces. These insights will create new opportunities for applications in chemistry, nanotechnology, and nanomedicine.

Nanoparticle induced charge redistribution of the air-water interface and its role in regulating nanoparticle spatial distributions

249th National Meeting (2015)

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