Add a sprinkling of copper atoms for a hydrogen-rich syngas

Scientists have developed a new recipe for creating synthesis gas mixtures, or syngas, which involves sprinkling a pinch of copper atoms atop a gold surface. The new material supports a room-temperature electrochemical reaction that can convert carbon dioxide and water into syngas, a mixture of carbon monoxide and hydrogen that is an important precursor in the production of chemicals and synthetic fuels.

According to the researchers, syngas can be converted downstream into small molecules, like ethanol, or larger hydrocarbons, such as those in gasoline, by fermentation or thermochemistry. Designing a material and a process that can easily control the composition of syngas would be an important step in reducing the environmental impacts of these industrial processes.

The scientists report their new recipe in a paper in the Journal of the American Chemical Society. The study was led by Peidong Yang, senior faculty scientist at the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) Materials Sciences Division, and Edward Sargent, professor at the University of Toronto’s Department of Electrical and Computer Engineering.

“We know of no other single electrocatalyst that combines high production rates with such wide-ranging syngas composition control,” said Yang, who is also a professor of chemistry at the University of California, Berkeley. “Many processes that utilize syngas require different compositions of gas, so we wanted to create a family of electrocatalysts that can be easily tunable.”

The researchers found they could control the amount of carbon monoxide and hydrogen generated by the electrocatalyst by simply adjusting the amount of copper atoms layered onto a nanostructured gold surface.

“The copper changes the strength with which CO₂ binds with the surface,” explained study lead author Michael Ross, a postdoctoral researcher in Yang’s lab. “A nanostructured surface that is primarily gold yields mostly carbon monoxide. To produce a mixture that is more hydrogen-rich, we add more copper.”

The researchers used X-ray photoelectron spectroscopy techniques at Berkeley Lab’s Molecular Foundry to quantify the amount of copper required on the gold electrocatalyst to produce different syngas mixtures. For example, a one-atom-thick layer of copper covering the gold surface can produce a two-to-one mixture of hydrogen to carbon monoxide. When the gold is left unadulterated, the hydrogen-to-carbon monoxide mix is one-to-10, demonstrating a wide flexibility in syngas output.

“If these electrocatalysts could be scaled up to work in industrial reactors, we could make syngas using renewably generated electricity and CO₂,” said Ross. “Syngas is currently being converted into methanol, diesel fuel and other useful chemicals all over the world. This could make the production of these chemicals much more sustainable.”

This story is adapted from material from the Lawrence Berkeley National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.