Ruthenium is widely used to accelerate chemical reactions, but its scarcity and cost make efficient use of the metal an important research goal. One approach is to disperse ruthenium as individual atoms, allowing a larger proportion of the metal to participate in reactions than in larger particles.
Researchers at Tohoku University, working with the University of Tsukuba, Kyoto University and The University of Osaka, have developed a method for producing high-density ruthenium single-atom catalysts. The material can convert carbon dioxide into formic acid, a raw material used by several industries. The findings were published in Angewandte Chemie International Edition.
The main challenge was preventing ruthenium atoms from joining together when larger amounts of the metal were incorporated into the catalyst. The team designed molecules with a more flexible structure, which could accommodate the atoms more effectively. Heating these molecules produced an organized, porous carbon material that held the ruthenium atoms apart.
Using this process, the researchers achieved a ruthenium concentration of up to 11% by weight. The source article says conventional ruthenium single-atom catalysts typically contain less than 2%.
Tests showed that the catalyst converted carbon dioxide into formic acid with more than 99% selectivity, indicating that very few unwanted byproducts were generated. Its performance remained high after repeated use, with no observed clumping of the ruthenium atoms or damage to the carbon structure.
The researchers say the approach could support more efficient use of limited supplies of valuable metals. They plan to investigate whether the same strategy can be applied to other precious metals, including platinum, palladium and iridium.
Sources: Phys.org.