A team of researchers — including scientists from Stanford University and SLAC National Accelerator Laboratory — have discovered how to improve catalytic performance using nanotechnology. The scientists published their findings on May 18 in the scientific journal Nature Communications.
Chirranjeevi Balaji Gopal, a former postdoctoral researcher at Stanford, is the lead author on the study. Other Stanford co-authors include former postdoctoral researcher Max Garcia-Melchor, graduate students Sang Chul Lee, Yezhou Shi, Matteo Monti and Zixuan Guan, and Professor of Materials Science and Engineering Robert Sinclair. From SLAC, researchers include former staff scientist Aleksandra Vojvodic and Assistant Professor of Materials Science and Engineering and faculty scientist William C. Chueh.
This new study found that it was possible to enhance the ability of a common industrial catalyst to store oxygen — a crucial function of the catalyst — just by stretching or compressing the catalyst a small amount, thereby improving its overall performance (catalysts work to accelerate reactions between chemical substances). The industrial catalyst used in this study was cerium oxide, also known as ceria.
“The oxygen storage capacity of ceria is critical to its effectiveness as a catalyst,” Vojvodic told Stanford News. “The theoretical expectation based on previous studies is that stretching ceria would increase its capacity to store oxygen, while compressing would lower its storage capacity.”
However, this new study disproves the traditional predictions surrounding stretching and compressing ceria by showing that compressing the catalyst actually improves its ability to store oxygen instead of diminishing it.
Using nanotechnology, the research team applied enormous pressure — 10,000 times the pressure of the Earth’s atmosphere — to microscopic films of ceria. The researchers found that when the molecules stretched and compressed under pressure, not only did the films exhibit no physical malformations from the stress, but the oxygen-storing capacities of the films had improved.
“We discovered that the strained films exhibited a fourfold increase in the oxygen storage capacity of ceria,” Gopal explained. “It doesn’t matter if you stretch it or compress it. You get a remarkably similar increase.”
These findings have wide-ranging implications for the future of industrial catalysts. Ceria is used in products ranging from self-cleaning ovens to solar water splitters to vehicle exhaust systems.
“Ceria stores and releases oxygen as needed, like a sponge,” Chueh said. “We discovered that stretching and compressing ceria by a few percent dramatically increases its oxygen storage capacity. This finding overturns conventional wisdom about oxide materials and could lead to better catalysts.”
Contact Sarah Wishingrad at swishing ‘at’ stanford.edu