Subnanometer Tracking of the Oxidation State on Co₃O₄ Nanoparticles by Identical Location Imaging and Spectroscopy

Area of Science:

• Catalysis
• Materials Science
• Surface Science

Background:

• Understanding catalyst behavior under reaction conditions is crucial for developing new catalytic processes.
• Traditional operando electron microscopy is limited by achievable reaction conditions and electron beam artifacts.
• Atomic-resolution imaging and spectroscopy under realistic conditions are needed to elucidate catalytic mechanisms.

Purpose of the Study:

• To introduce a novel quasi in situ approach combining identical location imaging and spectroscopy (ILIAS) to overcome limitations of conventional electron microscopy.
• To enable high-temperature and high-pressure studies in various gaseous environments without electron beam interference.
• To provide unprecedented insight into the structural evolution and surface reactivity of nanoparticles during catalytic reactions.

Main Methods:

• Development and application of the ILIAS technique for quasi in situ analysis.
• High-resolution imaging and spectroscopy of catalyst surfaces under controlled thermal and gas treatments.
• CO titration experiments to probe surface oxygen species and assess reactivity.

Main Results:

• Demonstrated the capability of ILIAS to resolve the structural evolution of Co3O4 spinel nanoparticles.
• Tracked changes in surface oxidation states before and after reductive or oxidative thermal treatments.
• Identified highly active oxygen species formed during thermal treatment through CO titration.

Conclusions:

• ILIAS provides a powerful tool for studying catalytic materials under industrially relevant conditions with atomic resolution.
• The study reveals critical insights into the interplay between pretreatment conditions and the surface reactivity of Co3O4 nanoparticles.
• This approach paves the way for a deeper understanding of catalytic processes and the design of improved catalysts.