SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Solid-Liquid Interfaces I: Structure and Spectroscopy

O 60.4: Talk

Wednesday, March 29, 2023, 15:45–16:00, TRE Phy

Facet-dependent surface charge and hydration of SrTiO3 nanoparticles at variable pH — •Igor Siretanu, Su Shaoqiang, Bastian Mei, Dirk van den Ende, Guido Mul, and Frieder Mugele — Physics of Complex Fluids and Photocatalytic Synthesis Groups, MESA+ Institute, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands

Anisotropy of shape and surface properties determine the functionality of faceted nanoparticles in various contexts including facet selective colloidal self-assembly, biosensing, improved photo/electrocatalytic activity and ions uptake. The characteristic surface proprieties and function of solid-liquid interfaces of crystalline faceted nanoparticles are believed to be essential for their performance but remains poorly understood and difficult to characterize and quantify. We use dual scale Atomic Force Microscopy to measure electrostatic and hydration forces of faceted SrTiO3 nanoparticles in aqueous electrolyte at variable pH. We demonstrate (i) the ability to quantify strongly facet-dependent surface charges yielding isoelectric points of the dominant {100} and {110} facets that differ by as much as 2 pH units, ii) fluids composition controlled facet-dependent accumulation of oppositely charged (SiO2) particles, and iii) that atomic scale defects can be resolved but are in fact rare for the samples investigated. Atomically resolved images and facet-dependent hydration structure suggest a microscopic hydration and charge generation mechanism.