A team at Cornell University led by Professor Peng Chen has developed an internal reflection fluorescence microscope that is more versatile than commercial models designed to observe a catalyst at work. This is a first and an important breakthrough event.

“Ingenious” as described by the University writer Bill Steele, the microscope is part of a method to observe the behavior of single nanoparticles of a catalyst all the way down to the resolution of individual catalytic events.

The team’s observations show that not all nanoparticles in a batch are created equal. Some carry out their reactions in different ways than others. The team also directly observed that every nanoparticles changes the speed of its catalytic reaction over time, and they have measured the time scale.

Catalysts are an intense area of interest and research because they offer higher speeds in chemical and biological reactions, permit reactions that otherwise wouldn’t happen naturally or in standard procedures, make industrial processes cheaper and more controllable and offer other advantages. The range of catalyst uses is broadening with each new discovery.

Peng Chen, a Cornell assistant professor of chemistry and chemical biology says, “Understanding the fundamental principles that govern the catalyst activity can help us to design new catalysts. Nanoparticles are dynamic entities. Maybe we can think about designing smart catalysts that can adapt to different conditions.”

The research is so far, a result from a single catalyst. The team immobilized spherical gold nanoparticles about 6 nanometers in diameter on a glass surface and flowed a solution of a dye over them. The catalyst changes molecules of the dye into a new fluorescent form. A dye molecule briefly binds to the surface of the gold, where an oxygen atom is removed. The new molecule fluoresces, and a blip of light appears remaining until the molecule releases from the catalyst. Using the new microscope that focuses on a very thin plane, the researchers made a “movie” with one frame every 30 milliseconds. The researchers were able to isolate the blips from individual nanoparticles and identify single catalytic events.

Nanocatalyst Graphic

Nanocatalyst Graphic Click for Extended Explanation

The method reveals two slightly different reaction patterns: On some nanoparticles the dye molecule binds to the surface, are changed and then releases. On others, after the change the molecule moves to a new position before it releases. And on some nanoparticles, both types of reaction occur. The nanoparticles, Chen explained, are not perfectly spherical, and different parts of the gold crystal are exposed at different places on the surface. The current idea is this may account for the different reaction patterns.

Reactions at the same sites also varied in their timing. The time a fluorescent molecule remains at a given site might be short, then longer, then short again. The explanation, the researchers said, is that the catalytic reaction also causes a restructuring of the surface of the gold, and this causes the subsequent reactions to take place faster or slower. Later, the gold surface recovers to its original structure, and the reaction returns to its original timing.

The press release writer quotes the team as saying “For the first time, we could provide a quantitation on the restructuring timescales at tens to hundreds of seconds.”

This research is only on a single catalyst, but the door is now opened for at least one path for a deeper understanding of catalysts at work. It’s a good start on what will surely be a growing field in catalyst research and development. The very idea that catalyst operations can be observed and improved implies that catalyst improvements could be coming much faster and with better results at an ever-increasing rate.

While congratulations is in order to the team its worth noting that the funding came from the National Science Foundation, and by the Petroleum Research Foundation of the American Chemical Society. The support for the research is being provided by the Cornell Center for Materials Research.

The research by team is described in the online edition of the journal Nature Materials and will appear in a forthcoming print edition and is available now to paying subscribers or single article download.


5 Comments so far

  1. Garry G on November 21, 2008 10:17 AM

    Thanks for the post…

    I’m always eager to track the progress of work around catalysts involved in basic energy systems. This is another announcement to note… The era of nanoscale science and engineering is certainly going to be exciting! It’s nice to have a peak at what’s actually going on!

    Garry G

  2. Another Way to See Catalysts At Work Plus a New Class of Catalysts | New Energy and Fuel on November 28, 2008 6:07 AM

    […] seems to be a breakout month for catalysts. We just looked a few days ago at a method to see them working and now Rice University has announced and Michael Wong’s team has published their research in […]

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