Defining precise shapes of catalytic nanoparticles challenging

GRA Eminent Scholar Younan Xia and his colleagues in the Georgia Tech-Emory Department of Biomedical Engineering are working to understand many aspects of catalytic nanoparticles.  Their latest research investigates how surface diffusion — how atoms move from one site to another on nanoscale surfaces — affects the final shape of the particles.

Understanding the surface diffusion process is important for a wide range of applications that use specific shapes to optimize the activity and selectivity of nanoparticles, including catalytic converters, fuel cell technology, chemical catalysis and plasmonics.  “We want to be able to design the synthesis to produce nanoparticles with the exact shape we want for each specific application,” Xia said.  Controlling the shape of nanoparticles is especially important in catalysis and other applications using expensive metals like platinum and palladium.

Because diffusion rate is determined by temperature, with higher temperatures allowing particles to move around faster, the investigators varied both the temperature of the process used to deposit atoms and the rate at which the atoms were deposited.  They found that the ratio of the deposition rate to the diffusion rate determines the final shape. “Unless the atomic reaction is at absolute zero, you will always have some diffusion,” said Xia.  “But if you can add atoms to the surface in the places that you want them faster than they can diffuse, you can control the final destination of the atoms.”    Read more here>