ChemRxiv
These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
DLVO_IEP_nsZrOx_FBorghi.pdf (1.58 MB)
0/0

The Influence of Nanoscale Roughness on the Electrostatic Double Layer: the Shift of the Isoelectric Point of Cluster-Assembled Nanostructured Zirconia Films

preprint
submitted on 07.02.2018 and posted on 07.02.2018 by Francesca Borghi, Bianca Scaparra, Costanza Paternoster, Paolo Milani, Alessandro Podestà
We investigated the influence of the nanoscale surface morphology on the electrostatic double layer at corrugated surfaces in aqueous electrolytes. To this purpose, we have produced cluster-assembled nanostructured zirconium dioxide (ns-ZrOx, x ≈ 2) films with controlled morphological properties by supersonic cluster beam deposition (SCBD), and measured the double layer interaction using atomic force microscopy with colloidal probes. SCBD allowed tuning the characteristic widths of the corrugated interface (the rms roughness, the correlation length) across a wide range of values, matching the width of the electrostatic double-layer (the Debye length), and the typical size of nano-colloids (proteins, enzymes, and catalytic nanoparticles). To accurately characterize the surface charge density in the high-roughness regime, we have developed a two-exponential model of the electrostatic force that explicitly includes roughness, and better accounts for the roughness-induced amplification of the interaction. We were then able to observe a marked reduction of the isoelectric point of ns-ZrOx surfaces on increasingly rough surfaces. This result is in good agreement with our previous observations on cluster-assembled nanostructured titania films, and demonstrates that the phenomenon is not limited to a specific material, but more generally depends on peculiar nanoscale morphological effects, related to the competition of the characteristic lengths of the system.

History

Email Address of Submitting Author

alessandro.podesta@mi.infn.it

Email Address(es) for Other Author(s)

francesca.borghi@unimi.it, bianca.scaparra@studenti.unimi.it. costanza.paternoster@studenti.unimi.it, paolo.milani@mi.infn.it

Institution

Università degli Studi di Milano

Country

Italy

ORCID For Submitting Author

0000-0002-4169-6679

Declaration of Conflict of Interest

no conflict of interest

Exports