Before Rong Ye came to Cornell as one of the first Cornell Presidential Postdoctoral Fellows, he was already working on catalysis—an essential industrial and biological process whereby chemical drivers called catalysts accelerate reactions. Developing better industrial catalysts could lead to new fuels, more efficient solar energy conversions, improved chemical processing, and more.
As a PhD student at the University of California, Berkeley, Ye worked to optimize and characterize catalytic reactions, exploring the innovations that could be made by blending different types of catalysts—homogenous catalysts, accelerating reactants in the same phase, and heterogeneous, catalyzing reactants in a different phase. Often he was studying the process at the bulk or average level.
“So usually I would synthesize a catalyst and run the reaction without knowing much about what’s happening on the catalyst during the reaction process,” Ye says. “I only know about the end result.”
To Work in a Unique, Innovative Lab
When Ye heard about the Cornell Presidential Postdoctoral Fellows program, initiated in 2017 to bring the best and brightest to Cornell, he started researching faculty. He became very intrigued by catalysis research techniques used by Peng Chen, Chemistry and Chemical Biology. Chen has made innovative discoveries by applying a single-molecule imaging technique, developed for use in biological applications, to nanocatalysts. This allows his group to better understand and see exactly what’s happening on individual particles as catalysis occurs.
Ye had used synchrotron-based techniques to zoom in on catalysts at work before, but those high-performance instruments are difficult to access, with only 10 or so facilities in the United States, one of which is at Cornell. Ye wanted to learn a more accessible technique. “Here, Peng has a very unique way of using optical microscopy to look at what happens on the catalysts in real-time, using a relatively simple setup. I was fascinated by this capability,” he says.
With these tools, Ye hopes to make discoveries that uncover unknown fundamentals of the process. “Catalysis research is often kind of a black box,” he says. “You don’t know what’s happening. And we really need to understand that catalytic process at a single-particle level to better design the next-generation catalysts. Until we understand it, all the development is trial and error.”
Going Beyond the Limits of Nonfluorogenic Reactions
One of Chen’s methods employs optical microscopy to see and study the workings of metal nanocatalysts. With light, for example, metal particles might catalyze a reaction that breaks a bond between nitrogen and oxygen. When this bond is broken, the reaction generates a single fluorescent molecule, which can be detected by the microscope.
“We are now trying to see whether we can break this limit, to look at reactions that are not fluorogenic…it will be a breakthrough in science… Peng is really the pioneer in doing such a thing.”
This method has its limits, and one of Ye’s projects will be to expand the technique’s capabilities. “Using optical microscopy to follow the reaction is usually limited to fluorogenic reactions, the reactions that generate fluorescence,” Ye says. “We are now trying to see whether we can break this limit, to look at reactions that are not fluorogenic. If we get the target, it will be a breakthrough in science, but we need to change some technical details. Peng is really the pioneer in doing such a thing.”
In another project, Ye will work on understanding how catalysis works in the process of polymerization, whereby synthetic units are bound together to make polymers, which make up materials like plastics. Chen’s lab recently made headlines—in Science—when they examined the growth of a single polymer for the first time.
They found that the polymerization process is not continuous but proceeds in steps. The polymer forms entanglements—which the team called hairballs—that unravel, leading to spurts in the extension of the polymer. This phenomenon has consequences for the growth rate of the polymer and the ability to predict the properties of polymers when designing new materials. “The property of the polymer really depends on the composition and also possibly on the growth rate,” Ye says.
Making better polymers and materials could have broad impact and applications. Polymers are currently vital to the military, for example, making up key components in soldier armors and medical supplies for wounded soldiers.
During his time in Ithaca, Ye will investigate polymerization further. “The step-wise extension is one phenomenon the lab saw, but we are not sure whether every type of polymer behaves that way,” he says. “We might see something very different. We don’t know until we test it.”
The Excitement of New Experiences
Having studied catalysis at the bulk level, and now learning how to zoom in to single particles to make discoveries there, will provide Ye a well-rounded research background moving forward. “The technique itself is interesting, and it isn’t what I’ve known before,” Ye says. “That will certainly fill my knowledge gap and make me a better researcher in general. It will be very good for me.”
Having grown up in China and earning his PhD on the West Coast, Ye is also looking forward to learning about the East Coast region of the United States. “Coming here fills my knowledge gap in the area as well,” he says.
The facilities at Cornell and the prestige of the fellowship program also lured Ye. “I feel really lucky that I saw it and applied and got it,” he says. “I’m really excited about the possibilities.”