Scientists catch catalysis in action at the atomic level for the first time

Amazing stuff!

"The reaction involves the removal of hydrogen atoms from alcohol molecules. In amazing new videos, individual atoms are seen moving and shaking during the reaction. ..."

From the highlights and abstract:

"The bigger picture

Catalysis enormously benefits today’s society—from energy production, fertilizers, advanced materials, and fine chemicals to pharmaceuticals—where heterogeneous catalysts comprise a pivotal 85% of industrial processes.

However, unraveling the atomistic intricacies of these processes remains challenging yet essential for creating greener, more atom-efficient next-generation catalysts. Here, we focus on studying the mechanism of sustainable H2 production via catalytic alcohol dehydrogenation over a single-site carbon-bound MoO2 catalytic center. We seek to visualize species along the mechanistic pathway through atomic-resolution transmission electron microscopy. Combining those results with data from other complementary experimental and theoretical characterization tools unveils the relationship of key intermediates along the complex dehydrogenation reaction pathway and provides essential clues for enhancing catalytic activity.

Highlights

• Organic intermediate dynamics are observed on the catalyst surface

• EXAFS, XANES, XPS, DFT, and kinetic analyses support the findings

• A new reaction pathway is proposed from experiments and theory

Summary

Heterogeneous catalysts dominate the chemical industry but, unlike homogeneous catalysts, typically feature diverse, incompletely defined active sites. Thus, describing their structure-activity relationships remains challenging.

In contrast, molecularly defined single-site heterogeneous catalysts (SSHCs) are poised to address these challenges and provide new avenues for catalysis research and development.

The present study explores eco-friendly H2 production mediated by discrete MoO2 sites supported on carbon nanohorns (CNHs) and active for alcohol dehydrogenation.

Although informative, detailed extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), X-ray photoelectron spectroscopy (XPS,) kinetic measurements, and density functional theory (DFT) analysis alone cannot provide a full molecular picture of the reaction pathway.

Here, using single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM), we propose the identification of four key catalytic intermediates anchored to CNHs and uncover a new reaction pathway involving alkoxide/hemiacetal equilibration and acetal oligomerization. These intermediates are inferred through a combination of theory and SMART-EM, showcasing the potential of SMART-EM as a complementary tool for exploring mechanistic hypotheses in catalysis."

WATCH: Scientists catch catalysis in action at the atomic level for the first time

Watch a live catalytic event in real time (original news release) "New observations could lead to more efficient catalysts for green hydrogen production"

Atomic-resolution imaging as a mechanistic tool for studying single-site heterogeneous catalysis (no public access)

Atomic-Resolution Cinematography of Catalytic Intermediates over a Single-Site Heterogeneous Catalyst (preprint, open access)

Graphical abstract