A new study from scientists at Yale University and the University of Missouri shows that catalysts made with manganese can efficiently convert carbon dioxide into formate. Manganese is widely available and low cost, making it an attractive alternative to expensive metals. Formate is considered a promising material for storing hydrogen, which could help power the next generation of fuel cells.

The research was published in the journal Chem. The lead authors are Yale postdoctoral researcher Justin Wedal and University of Missouri graduate research assistant Kyler Virtue. Senior authors include Yale professor Nilay Hazari and University of Missouri professor Wesley Bernskoetter.

Why Hydrogen Fuel Cells Matter

Hydrogen fuel cells work by turning chemical energy from hydrogen into electricity, similar to how a battery operates. Although the technology holds promise for clean energy, large-scale adoption has been limited by the difficulty and cost of producing and storing hydrogen efficiently.

"Carbon dioxide utilization is a priority right now, as we look for renewable chemical feedstocks to replace feedstocks derived from fossil fuel," said Hazari, the John Randolph Huffman Professor of Chemistry, and chair of chemistry, in Yale’s Faculty of Arts and Sciences (FAS).

Formate as a Hydrogen Carrier

Formic acid, the protonated form of formate, is already manufactured at an industrial scale. It is commonly used as a preservative, an antibacterial agent, and in leather tanning. Many scientists also see it as a practical source of hydrogen for fuel cells, provided it can be made in a sustainable and efficient way.

Today, most industrial formate production relies on fossil fuels, which limits its long-term environmental benefits. Researchers say a cleaner alternative would be to produce formate directly from carbon dioxide in the air. This approach would both reduce greenhouse gas levels and create a useful chemical product.

The Catalyst Challenge

Transforming carbon dioxide into formate requires a catalyst, and that has been a major obstacle. Many of the most effective catalysts developed so far depend on precious metals that are costly, scarce, and often toxic. More abundant metals tend to break down quickly, which reduces their ability to drive the chemical reaction.

How Manganese Outperformed Expectations

The research team developed a new strategy to overcome this problem. By redesigning the catalyst structure, they significantly extended the working lifetime of manganese-based catalysts. As a result, these catalysts performed better than most precious metal alternatives.

According to the researchers, the key improvement came from adding an extra donor atom to the ligand design (ligands are atoms or molecules that bond with a metal atom and influence reactivity). This change helped stabilize the catalyst and maintain its effectiveness.

"I’m excited to see the ligand design pay off in such a meaningful way," said Wedal.

Broader Implications for Clean Chemistry

The team believes this approach could be applied beyond carbon dioxide conversion. Similar design principles may improve catalysts used in other chemical reactions, potentially expanding the impact of the work.

Yale researchers Brandon Mercado and Nicole Piekut also contributed to the study. Funding for the research was provided by the U.S. Department of Energy’s Office of Science.