New Haven, Conn. — The road to a more sustainable planet may be partially paved with manganese.

According to a new study by researchers at Yale and the University of Missouri, chemical catalysts containing manganese — an abundant, inexpensive metallic element — proved highly effective in converting carbon dioxide into formate, a compound viewed as a potential key contributor of hydrogen for the next generation of fuel cells.

The new study appears in the journal Chem. The lead authors are Yale postdoctoral researcher Justin Wedal and Missouri graduate research assistant Kyler Virtue; the senior authors are professors Nilay Hazari of Yale and Wesley Bernskoetter of Missouri.

Like a battery, a hydrogen fuel cell converts chemical energy from hydrogen into electricity. One challenge for widespread use of such technology is developing cost-efficient ways to produce and store hydrogen.

“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).

Formic acid, the protonated form of formate, is a commodity chemical produced at an industrial scale for use as a preservative, antibacterial agent, and tanning agent. It is also viewed by many researchers as a likely source of hydrogen for fuel cells — if it can be produced sustainably and effectively.

Currently, industrial formate production involves the use of fossil fuels, and is thus not considered a sustainable option in the long-term. A more planet-friendly approach, researchers say, is to create formate from atmospheric carbon dioxide, essentially removing greenhouse gas and converting it into a useful product.

But to do this, a catalyst is required. And therein lies the challenge for researchers. Many of the effective potential catalysts in development are based on precious metals, which are expensive, less abundant, and have high toxicity. On the other hand, metal catalysts that are more abundant, more sustainable, and less expensive have tended to be less effective since they decompose rapidly, which limits their ability to convert carbon dioxide into formate. Hazari’s team offers a new approach.

The researchers were able to extend the catalytic lifetime of manganese-based catalysts to such a degree that their effectiveness outpaced most of the precious metal catalysts. The key innovation, they said, was to stabilize the catalysts by adding another donor atom into the ligand design (ligands are atoms or molecules that bond with a metal atom and influence reactivity).

“I’m excited to see the ligand design pay off in such a meaningful way,” said Wedal. The researchers also said their approach may be broadly applied to other catalytic transformations, beyond the conversion of carbon dioxide to formate.

Yale’s Brandon Mercado and Nicole Piekut are co-authors of the study. Funding for the research came from the U.S. Department of Energy’s Office of Science.