Nanoparticles of precious metals resembling precious stones shine as catalysts

A research team at Northwestern University has developed a new method for producing highly desirable catalysts from metal nanoparticles that can improve the quality of fuel cells, among other applications. The researchers also discovered that the method can take spent catalysts and recycle them into active catalysts.

Made mainly of precious metals, these coveted catalysts are shaped like gems. Each particle has 24 different faces that present atoms on the surface so as to make them more catalytically active than those available commercially.

The methodology uses base metal precursors and, using heat and stabilizing trace elements, rapidly transforms their form into highly catalytically active structures. Commercial products such as fuel cells, important sources of clean energy, depend on these catalysts.

The method is general. The study shows that it works with five monometallic nanoparticles and a library of bimetallic nanoparticles, covering seven different metals, including platinum, cobalt and nickel.

"Many of these precious metals are responsible for some of the most important chemical transformations used in the chemical, petroleum and fuel cell industries," said Chad A. Mirkin, professor of chemistry at George B. Rathmann of Weinberg. College of Arts. Science, who led the research.

"We can not only prepare commercially desirable catalysts, but also recycle used fuel cell catalysts in their most active forms.The catalysts slowly degrade over time and change," says Mirkin.

The study, which includes both simulations and experiments, will be published on September 13 in the journal Science.

The new catalysts are called high-facet facet nanoparticle catalysts – an optimal form for accelerating chemical reactions. The Mirkin team discovered that their platinum catalysts were 20 times faster than the low-index commercial form for the reaction to electrooxidation to formic acid (based on platinum content).

"Platinum in high-index facet form is different and better than in other forms of nanoparticles," said Chris Wolverton, co-author of the study and Jerome B. Cohen Chair Professor. in Materials Science and Engineering at the McCormick School of Northwestern Engineering.

"It's all about chemistry," said Mirkin, also director of the Northwestern International Nanotechnology Institute.

Mirkin's multidisciplinary team also includes Vinayak Dravid, Abraham Harris Professor of Materials Science and Engineering, at McCormick.

Catalysis contributes to more than 35% of the world's gross domestic product, according to the American Chemistry Council. The new catalysts can be mass-produced and without the use of ligands, which can compromise catalytic activity. The process of both creating new catalysts and recycling used catalysts is fast and scalable.

Mirkin said the technology might not be far from being used commercially. "This type of technology is ready to be extended and widely used in catalysis," he said.

the Science The document entitled "Regulating the Form of High-Faceted Nanoparticles by Disintegration". The first author is Liliang Huang, a graduate student from Mirkin's laboratory.