Study distinguishes structure and function of catalytically active sites on copper that reduce CO₂

In the ongoing drive to remove greenhouse gases from the environment and put them to good use, researchers have known for years that copper catalysts in electrochemical cells can convert carbon dioxide to ethylene, alcohols, and other valuable compounds. What they don’t know are the atomic-level details than enable low-cost copper to do this carbon-coupling chemistry. These details could help design catalysts that provide higher yields of desired products.

By combining experiments, high-throughput computational screening, and quantum calculations, a team led by Jinlong Gong of Tianjin University has worked out the atomic structure of three types of active sites on a well-studied copper catalyst and distinguished sites that produce ethylene from ones the generate alcohols (Nat. Commun. 2021, DOI: 10.1038/s41467-020-20615-0).

These catalysts typically produce a range of products containing two or more carbons, explains Cao Thang Dinh of Queen’s University, who was not involved in the study. But better understanding of the active sites, he says, could help make a single product. These results provide the type of guidance needed for designing highly selective catalysts for CO₂ reduction, Dinh says.

The team analyzed binding energies and other properties of reaction intermediates at more than 150 types of catalyst surface sites. The results show that certain arrangements of copper atoms with square-like geometries drive the coupling reactions.

Probing further, they found that two distinct square arrangements catalyze production of ethylene. They also identified a third type of site that produces alcohols by hindering the ethylene pathway and stabilizing CH₃CHO intermediates that go on to form alcohols.

These results “will inspire the imagination of experimentalists,” says Kazunari Domen of the University of Tokyo. But it will be challenging to make catalysts with the desired activity and selectivity at an industrial scale, he says.