Researchers from Northwestern University and international collaborators achieved a groundbreaking feat by observing catalysis at the atomic level in real time. Using a technique called single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM), the team was able to film the atomic motion during a chemical reaction. This innovation allowed researchers to identify short-lived intermediate molecules and a previously hidden reaction pathway.
The study, led by Northwestern's Yosi Kratish and Tobin J. Marks, aimed to enhance the understanding of catalysts, which play a crucial role in the production of fuels, fertilizers, plastics, and medicines. Observing catalysis at the atomic level helps in designing more efficient and eco-friendly chemical processes. The findings were published in the journal Chem.
Kratish expressed the significance of their achievement by stating, "By visualizing this process and following the reaction mechanisms, we can understand exactly what’s happening in the finest detail." Meanwhile, Marks emphasized the importance of this understanding, saying, “Catalysts make modern life possible. To make chemical processes more efficient and environmentally friendly, we need to understand exactly how catalysts work at the atomic level."
The researchers used SMART-EM to observe a seemingly straightforward catalytic reaction: removing hydrogen atoms from an alcohol molecule. This technique, developed by the University of Tokyo’s Professor Eiichi Nakamura and his team, captures rapid sequences of images to create dynamic process videos, which Nakamura calls "cinematic chemistry."
To better study the reaction, the team developed a single-site heterogeneous catalyst composed of molybdenum oxide particles on a cone-shaped carbon nanotube. The use of SMART-EM unveiled a previously unknown step in the reaction, where aldehydes did not escape into the air as initially hypothesized. Instead, aldehydes linked to form short-chain polymers, revealing an unexpected reaction pathway. Furthermore, the aldehyde reacted with alcohol to form hemiacetal, which transforms into other products.
"This is a big breakthrough,” Kratish said. “SMART-EM is changing the way we look at chemistry.” The researchers hope to further explore and potentially isolate these intermediate forms, controlling the energy input and studying organic catalytic transformations' kinetics.
The study received support from the U.S. Department of Energy, marking a substantial advancement in catalysis understanding.