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Dr. YuYe Tong: Bimetallic Nanoparticles and the Changing Face of Energy Research

"When you reduce the size of an object, new phenomena happen." —Dr. YuYe Tong

October 27, 2008

By Kara Burritt

Dr. YuYe Tong's research has brought him full circle. Years of working in the lab have taken the Associate Professor of Chemistry back to the starting place of his professional career—though it was not retreat, but rather progress, that brought him there. In June 2008 Tong returned to his alma mater, Fudan University in Shanghai, to present a talk as well as a poster on his recent research breakthrough.

Tong, who in addition to teaching at Georgetown also manages a nanoparticle research lab on campus, led a group of seven other Georgetown science professors to Fudan for the sixteen-talk and sixteen-poster science symposium with Fudan professors. Having earned his bachelor's and master's degrees at Fudan, Tong's involvement in the symposium allowed him to revisit his roots while displaying the breakthrough research his lab recently produced in characterizing bimetallic nanoparticles, which is important to the field of engineering clean energy-production technology.    

Characterizing materials, or determining their properties, is a routine part of chemistry that is made more difficult when working with radically smaller nanoparticles. Nanoparticles are so small that they are handled in terms of atoms and are measured in terms of nanometers, of which one is equal to a billionth of a meter. Working on this molecular level presents many challenges, as available technology cannot easily access some of a material's properties on such a small scale.  

However, it is critical to understand nanoparticle properties because as a material approaches nanoscale, its properties and behavior are altered as a result of the atomic structure changing. "When you reduce the size of an object, new phenomena happen," explains Tong. Such phenomena include chemical reactivity, which is at the core of energy production. Both the emergent properties and the ability to modify shape and structure at the atomic level make nanoparticles invaluable in the effort to maximize the efficiency of clean energy production.  

Given the importance of establishing the relationship between nanoparticle materials and their behavior in order to utilize them, Tong’s lab focuses its research on identifying chemical and physical properties of nanoparticles. The ultimate goal is to better understand what causes the exhibited behavior. "The first step in chemistry is always determining the structure and composition," he says.

Yet one aspect of composition had been out of reach in the field of nanoscience until Tong’s recent breakthrough: the spatial distribution of an element within a bimetallic nanoparticle.  

Bimetallic nanoparticles, created by combining two metals, are highly reactive and thus have great promise as catalysts of energy production. This gives bimetallic nanoparticles potential for a range of applications, like alternative energy production and materials manufacturing.

However, without understanding how each element is distributed within the nanoparticle, it is impossible to fully understand the structural and surface-bonding properties that are at the source of reactivity in bimetallic nanoparticles. "It's important to determine the distribution of each element separately," says Tong, "because local composition determines reactivity."

Driven by this as yet unachieved goal, Tong recently developed a technique to identify the local composition of platinum (Pt) within a lab-engineered bimetallic nanoparticle. For the study, Tong, his Korean collaborators and his research assistants created bimetallic nanoparticles by synthesizing platinum (Pt) with ruthenium (Ru) at 50% content each. These metals share similar properties, and each exhibits catalytic potential.    

To distinguish one element's distribution from the other's after synthesis, Tong used 195Pt NMR spectroscopy, a technique that measures the magnetic resonance frequencies of nuclear spin in order to characterize molecules. Using this technology he developed a procedure sensitive enough to quantify the concentration of platinum (Pt) along the radial dimension of the Pt-Ru nanoparticle. The specificity of this measurement is unprecedented in the study of bimetallic nanoparticles.

"Many other techniques do not have spatial chemical resolution at this small scale," Tong explains.  "The key breakthrough is that the technique can probe local elemental distribution of platinum-based bimetallic nanoparticles along the radius of the particles."

The technique Tong developed to determine the presence of platinum in his sample will be valuable in characterizing other platinum-containing bimetallic materials. Ultimately this technique has broader applications. Says Tong, "It can be used to better the rational design of bimetallic materials." Because bimetallic nanoparticles are so inherently reactive, a good understanding of how the elemental distribution determines their reactive properties is essential for optimizing them in real-world use, like in the development of energy-production technology.

It is this kind of promise for development innate in Tong's research that gives it such widespread importance. Tong’s presentation of this research at June's science symposium was a part of a mutually beneficial collaboration of scientific ideas, the type of partnership that will have repercussions beyond just lab research. Out of this event Georgetown will likely recruit a greater range of science students, says Tong.  

"By presenting ourselves in Fudan, one of the best universities in China, we will become known to students," he explains, referencing the fact that in China, Georgetown is widely regarded as a humanities institution despite its advanced science programs. "It is good PR for Georgetown sciences in China." 

Tong predicted such benefits when he first considered the symposium with administrators: "Once this [symposium] happened, we would be recognized by the quality of our science."  Now he affirms, "Indeed, it is happening."
 
This growing international reputation may mean that Georgetown could soon welcome—or may already host—another student or professor of chemistry who will eventually find himself returning to the roots of his career back home in China, ground-breaking research in hand.

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