WashU engineer seeks new catalysts from 2-D materials

Electrochemical systems, such as fuel cells, depend on catalysts to increase the rate of the chemical reactions. A team of engineers and materials scientists at Washington University in St. Louis and the University of Illinois at Chicago (UIC), plan to find new, highly efficient catalysts based on 2-D materials, which could have a revolutionary impact in energy-related systems, such as in the conversion of carbon dioxide, a greenhouse gas, into energy-rich fuels.

Rohan Mishra

Rohan Mishra, assistant professor of mechanical engineering & materials science at WashU, received a four-year, $361,177 grant from the National Science Foundation to design these materials working in collaboration with Amin Salehi-Khojin, a mechanical engineer, and Robert Klie, a materials physicist, both at UIC. The grant is part of the Materials Genome Initiative launched by President Barack Obama in 2011 as a multi-agency initiative to create policy, resources and infrastructure that support U.S. institutions to discover, manufacture and deploy advanced materials efficiently and cost-effectively.

“Electrocatalysts are used in reducing carbon dioxide to carbon monoxide or into a hydrocarbon fuel, or to reduce oxygen for subsequent use in fuel cells or in lithium-air batteries,” said Mishra, a materials scientist in the School of Engineering & Applied Science. “We believe this will have applications in numerous areas.”

Currently, precious materials including platinum and silver nanoparticles are used as catalysts but are too costly for widespread commercial use. In 2004, researchers discovered graphene, sparking discovery of a variety of new 2-D materials that Mishra said are simply a sheet of atoms.

“My collaborators at UIC have recently discovered that when they take a particular class of 2-D materials called transition metal dichalcogenides and put them in ionic liquid, they get up to a 1,000-fold increase in catalytic activity,” Mishra said. “However, our goal is to understand within four years what makes certain 2-D materials such highly efficient catalysts and use this knowledge to design new 2-D materials and alloys that can lead to further improvement in catalytic activity. The eventual goal is to make them close to commercial catalysts with the hope that we won’t need platinum in cars working on fuel cells.”

Mishra will rapidly screen available and hypothetical 2-D materials using quantum-mechanical electronic structure calculations run on the world’s 12th most powerful supercomputer, the Stampede2 at the Texas Advanced Computing Center, to determine which might be promising candidates. Then, Salehi-Khojin will synthesize the best candidates and measure their catalytic activity. Klie will then characterize the synthesized materials at the atomic scale using sophisticated electron microscopes. Mishra will then feed the atomic structure of the materials, their activity and their electronic structure back to the supercomputers to build a machine-learning model with the goal of accurately predicting catalysts.

“We can’t synthesize and test each of the available 2-D materials and their alloys – that would take decades,” he said. “This is a closed-loop way of developing and discovering new materials using desirable properties from the atomic scale.”

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