Ruthenium (Ru) is a valuable metal used in catalysts to speed up chemical reactions in many industrial processes. It can help improve efficiency and reduce the energy needed for chemical production. However, because it is rare and expensive, scientists are looking for ways to make better use of it.

One promising approach is to use individual ruthenium atoms instead of larger metal particles, allowing more of the metal to take part in chemical reactions. The challenge, however, is finding a way to include large numbers of these atoms in a single catalyst.

To address this challenge, researchers at Tohoku University, working with the University of Tsukuba, Kyoto University, and The University of Osaka, have developed a new method for producing ruthenium single-atom catalysts. The durable, highly selective catalyst can convert harmful carbon dioxide (CO₂) into formic acid, which is a valuable raw material for many industries.

The findings were published in Angewandte Chemie International Edition on September 3, 2026.

"Single-atom catalysts can make better use of valuable metals by allowing more atoms to take part in chemical reactions," explains Associate Professor Takeharu Yoshii from the Advanced Institute for Materials Science (WPI-AIMR), Tohoku University. "However, when large amounts of ruthenium are used, the atoms tend to stick together, making it difficult to keep them separated. We developed a new way to hold individual ruthenium atoms in place within a carbon material, even at high concentrations."

To create the catalyst, the researchers designed molecules with a more flexible structure than those used in earlier methods, allowing them to better accommodate ruthenium atoms. The team then heated them to form an organized, porous carbon material. Using this method, they achieved a ruthenium content of up to 11% by weight, compared with typically less than 2% in conventional ruthenium single-atom catalysts.

The researchers also tested how well the new catalyst could convert CO₂ into formic acid. It achieved over 99% selectivity, meaning that very few unwanted byproducts were formed. Even after repeated use, the catalyst maintained its high performance, with no signs of the metal atoms clumping together or damage to the carbon structure.

This method could help researchers develop more efficient catalysts while making better use of limited metal resources. Building on these findings, the team plans to explore whether the same approach could be used with other precious metals, such as platinum, palladium, and iridium.