Facet-dependent charging and hydration of semiconducting SrTiO3 nanoparticles

Description

Anisotropy of surface properties is an essential feature of faceted nanoparticles that controls their behavior in many respects including self-assembly and aggregation, local chemical reactivity, electrophoretic mobility, and photo-/electrocatalytic activity. In this lecture, I will discuss an approach based on high resolution in situ AFM spectroscopy that allows us to probe the local surface charge and hydration with sub-particle resolution. Using nanoparticles of SrTiO3, a well-known photocatalyst, as an example I demonstrate that the isoelectric point of the dominant (110) and the (100) facets is different by 2 pH units. Atomically resolved images suggest a specific microscopic charge generation mechanism involving the different hydration structure on the two dominant facets. These findings have important consequences for the interpretation of conventional macroscopic averaging techniques such as zeta potential measurements, for colloidal self-assembly, and – specifically – for the activity of SrTiO3 and other semiconductor nanoparticles for photo- or electrocatalytic water splitting.

Period	5 Oct 2021
Held at	Leibniz Institute of Polymer Research Dresden (IPF), Germany