LIVERMORE, Calif. Scientists can now peer into the inner workings of catalyst nanoparticles 3,000 times smaller than a human hair within nanoseconds.
The findings point the way toward future work that could greatly improve catalyst efficiency in a variety of processes that are crucial to the world's energy security, such as petroleum catalysis and catalyst-based nanomaterial growth for next-generation rechargeable batteries. The work was performed in a collaborative effort by Lawrence Livermore National Laboratory and the University of California at Davis.
Using a new imaging technique on Lawrence Livermore's Dynamic Transmission Electron Microscope (DTEM), researchers have achieved unprecedented spatial and temporal resolution in single-shot images of nanoparticulate catalysts.
The DTEM uses a laser-driven photocathode to produce short pulses of electrons capable of recording electron micrographs with 15-nanosecond (one billionth of a second) exposure time. The recent addition of an annular dark field (ADF) aperture to the instrument has greatly improved its ability to time-resolve images of nanoparticles as small as 30 nanometers in diameter.
"Nanoparticles in this size range are of crucial importance to a wide variety of catalytic process of keen interest to energy and nanotechnology researchers," said UC Davis' Dan Masiel, formerly of LLNL and lead author of a paper appearing in the journal, ChemPhysChem. "Time-resolved imaging of such materials will allow for unprecedented insight into the dynamics of their behavior."
Previously, particles smaller than 50 nanometers could not be resolved in the 15-nanosecond exposure because of the limited signal and low contrast without ADF aperature. But by using DTEM's ADF, almost every 50-nanometer particle and many 30-nanometer ones became clearly visible because of the fast time resolution and high contrast.
"The stark difference between these two
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DOE/Lawrence Livermore National Laboratory