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Widespread adoption of hydrogen-powered vehicles is more likely than traditional electric vehicles. This requires fuel cells to convert hydrogen and oxygen into the water safely. This is a significant implementation issue.
Researchers at the University of Colorado Boulder are addressing one aspect of this roadblock. They are developing new computational tools, models, and tools to understand better and manage the conversion process. Hendrik Heinz is an associate professor at the Department of Chemical and Biological Engineering and leads the effort with the University of California Los Angeles. His research team published new findings in Science Advances.
Fuel cell electric vehicles combine hydrogen and oxygen in a tank to produce electricity. They can be charged without plugging in and having water vapor. These and other features make them attractive for green and renewable energy transportation.
Heinz stated that the key to making these vehicles viable is to find a catalyst in the fuel cells that can “burn” hydrogen with oxygen under controlled conditions to ensure safe travel. Researchers are also looking for motivation with high efficiency, a long life span in acidic solutions, and near-room temperature. Although platinum is widely used, it hasn’t proven easy to predict the reactions and best materials for scaling up or under different conditions.
Researchers have struggled for decades to predict complex processes. However, Heinz stated that nanoplates, nanowires, and other nanostructures had significantly progressed. We have created models for metal nanostructures, oxygen, water, and metal interactions, which exceed current quantum methods’ accuracy by more than ten times. These models allow for the inclusion of dynamics and solvents and reveal quantitative correlations between oxygen accessibility at the surface and catalytic activities in the oxygen reduction process.
Heinz stated that the quantitative simulations developed by his team show the interaction of oxygen molecules with different barriers, such as molecular layers made of water on the platinum surface. These interactions can distinguish between a fast or slow follow-on reaction and must be controlled to ensure the process works efficiently. These reactions occur very quickly — water conversion takes approximately a millisecond per sq. nanometer — and happen on a minimal catalyst surface. His team has figured out how to predict how these variables interact in an intricate and complex “dance.”
The computational and data-intensive methods described in the paper can be used to create designer nanostructures that would maximize the catalytic efficiency and possible surface modifications to optimize the cost-benefit ratio of fuel cells further, Heinz added. Heinz and his collaborators are currently exploring the commercial implications of this aspect. Heinz is using the tools to help study more potential alloys and gain additional insights into the mechanics.
He said the tools in the paper, including the interface force field to make molecular dynamics simulations more accurate by order of magnitude, can be used for other catalysts and electrocatalysts to achieve similar breakthroughs.
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