In Situ TEM Studies of Exsolution Active Material Systems

Dylan Jennings^a, Moritz L. Weber^b^,^c, Andrea Kirsch^d, Hongyu Sun^e, Christian H. Liebscher^a

^aAdvanced Transmission Electron Microscopy, Faculty of Physics and Astronomy & Research Center Future Energy Materials and Systems, Ruhr University Bochum, Germany

^bHydrogen Institute for Sustainability (HYDROGENIUS), Kyushu University, Japan

^cDepartment of Materials Science and Engineering, Massachusetts Institute of Technology, USA

^dOxidic Functional Materials, Faculty of Chemistry and Biochemistry & Research Center Future Energy Materials and Systems, Ruhr University Bochum, Germany

^eDENSSolutions B.V., Delft, The Netherlands

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

C2 Exsolution in Sustainable Catalyst Design

Palma, Spain, 2026 October 26th - 30th

Organizers: Moritz Kindelmann and Moritz L. Weber

Invited Speaker, Dylan Jennings, presentation 309
Publication date: 22nd July 2026

There are several purported benefits of exsolution catalysts, such as thermal stability and regenerability (through reoxidation). Currently, the mechanisms for these advantages are under discussion, and there remains some disagreement in the literature on how exsolved nanoparticles behave at the nanoscale. In situ experiments within the transmission electron microscope (TEM) provide a unique ability to investigate the behavior of exsolved nanoparticles with high spatial resolution. In this work, we utilize a variety of in situ TEM experiments to probe the behavior of exsolution-active materials during and after the exsolution reaction in several different systems.

First, we track the exsolution process from a compositionally complex spinel oxide through in situ gas experiments with simultaneous heating. Through a combination of heating while under a pressure of 1 bar of pure hydrogen up to 700 °C, we can observe the formation of metallic nanoparticles along with a restructuring of the oxide support. Furthermore, we show a progressive exsolution process occurs as different elements with differences in nobility exsolve from the support through electron energy loss spectroscopy at pressure and elevated temperature. By changing the gas atmosphere to oxygen while remaining at 1 bar pressure, we investigate the reversibility of the exsolution reaction in this system. The in situ results are compared with ex situ analyses on the same material, highlighting the dynamic and spatially resolved information gained from the use of in situ TEM techniques. We then contrast results from spinel oxides with in situ exsolution results from doped perovskite oxide thin films. Through the utilization of atomic resolution secondary electron imaging we demonstrate the formation of nanoparticles near and away from defects within the films, and that the perovskite structure remains stable. Additionally, we observe that defects not only act as nucleation sites, but also stabilize particles and prevent migration on the surface of the oxide support. Finally, an outlook on the in situ investigation of exsolution behaviors in the presence of external stimuli (i.e. strain, bias) is discussed.

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.