Single Atom Dynamics in Chemical Reactions | JoVE Visualize

Area of Science:

Heterogeneous catalysis
Materials science
Surface chemistry
Electron microscopy

Background:

Heterogeneous catalysis is vital for energy, healthcare, and pollution control, operating at the atomic level.
Understanding atomic-scale reaction mechanisms and structural evolution is key to improving catalyst performance.
Dynamic single atoms and clusters are increasingly recognized for their role in enhanced catalytic activity.

Purpose of the Study:

To highlight the development and application of environmental scanning transmission electron microscopy (ESTEM) for in situ atomic-level studies of gas-solid catalysts.
To provide insights into catalyst structural evolution and reaction mechanisms under realistic operating conditions.
To inform the rational design of future catalytic processes and materials.

Main Methods:

Development and utilization of atomic lattice resolution environmental transmission electron microscope (ETEM), advanced to environmental scanning TEM (ESTEM).
High-angle annular dark-field (HAADF) imaging for Z-contrast analysis, enabling discernment of metal atoms on lighter supports.
Real-time in situ observation of catalytic reactions at elevated temperatures and gas pressures.

Main Results:

Visualized dynamic reduction and migration of platinum atoms in Pt/C catalysts, revealing nanoparticles as reservoirs for low-coordination atoms and clusters.
Tracked oxidation fronts at the atomic level in copper and nickel nanoparticles using Z-contrast imaging.
Identified high concentrations of low-coordination Co0 active sites in pretreated cobalt/silica catalysts for Fischer-Tropsch synthesis.

Conclusions:

ESTEM provides unprecedented atomic-level insights into dynamic catalyst behavior under reaction conditions.
Understanding dynamic processes like atom migration and oxidation is crucial for catalyst design and regeneration.
The findings advance the fundamental understanding of heterogeneous catalysis, supporting the development of improved catalysts and chemical processes.