Researchers at the Massachusetts Institute of Technology (MIT) have uncovered why molybdenum-containing nitrogenase enzymes are more efficient at converting atmospheric nitrogen into ammonia—a breakthrough that could advance the development of low-energy ammonia production technologies.
Published in the journal Chem, the two studies show that while molybdenum does not directly bind nitrogen, it enhances the ability of nearby iron atoms to do so. This strengthens the crucial first step in breaking the strong nitrogen-nitrogen triple bond, enabling more efficient ammonia formation.
The researchers found that iron-sulfur clusters containing larger metals such as molybdenum or tungsten bind nitrogen more effectively than those containing smaller metals like vanadium, chromium, or iron.
A second study revealed that molybdenum improves electron sharing between metal atoms, allowing iron to transfer electrons more efficiently during nitrogen activation. This electronic cooperation lowers the energy required to initiate the reaction.
The findings provide new insights into biological nitrogen fixation and could help scientists engineer more efficient enzymes or design synthetic catalysts for ammonia production. Such technologies have the potential to reduce reliance on the energy-intensive Haber-Bosch process, which is currently used to manufacture most of the world’s ammonia for fertilisers.
The research was led by Daniel Suess, Associate Professor of Chemistry at MIT, and was supported by the U.S. Department of Energy, the National Science Foundation, and the National Institute of General Medical Sciences.
