Probing interfacial structure and dynamics around nanoparticles with X-rays and neutrons

by Prof. Mirijam Zobel (RWTH Aachen University)

Monday 30 Jan 2023, 14:30 → 15:30 Europe/Berlin

PH HS 3 (Physics Department)

Nanostructured solid-liquid and solid-gas interfaces play a key role not only during nanoparticle formation, but in a plethora of surroundings spanning from geochemical processes to heterogenous catalysis. Despite much progress in fine-tuning nanoparticle properties themselves, our understanding of the very interface of nanoparticles interacting with their surroundings is still limited. 

By joining insights form pair distribution function (PDF) and quasielastic neutron scattering (QENS), we aim to achieve an advanced understanding of the structure and dynamics of nanoscale interfaces. In contrast to classical crystallographic approaches, the PDF is utmost suited to characterize short-range order, allowing us to investigate solvent structures around colloidal, 3 – 15 nm sized metal oxide nanoparticles. We can access solvation and hydration shells and their extension into the bulk liquid via double-difference PDFs (dd-PDF), when subtracting contributions from bulk solvents and nanoparticles from the dispersion signal. [1] This dd-PDF approach is applied to gain detailed insight into self-assembly processes of mesocrystals [2] and transferred to nanoparticle-support interactions in heterogeneous catalysis [3]. Since structural reorganization at interfaces often affects dynamical properties concurrently, we tackle the interfacial dynamics of water molecules at iron oxide nanoparticle surfaces with QENS to correlate with hydration shell structures.

 

References:
[1] M. Zobel, R. B. Neder, S. A. J. Kimber, Science 347 (2015) 6219, 292

[2] J. Schlotheuber né Brunner, et al., Chem. Mater. 33 (2021) 23, 9119–9130

[3] M. Elfinger, et al., ChemSusChem 14 (2021), 1-8