Molybdenum-Based Catalyst Could Produce Sustainable Fuel and Chemicals

Molybdenum (Mo) is the critical component in an electrochemical hydride transfer catalyst that was examined by the King Abdullah University of Science and Technology (KAUST) researchers. The molybdenum-based catalyst brings sustainable fuel and chemicals one step closer to being an actual reality.

For a long time, platinum has been the catalyst of choice for electrochemical hydride transfer, a chemical process that has the potential to create valuable chemicals or carbon-free fuels. However, the use of this technology is severely limited by the fact that platinum is a precious metal that is both scarce and expensive.

Magnus Rueping and his team have demonstrated that molybdenum, a more abundant and affordable metal, has the potential to replace platinum in this process. Molybdenum sulfide and other molybdenum-based catalysts have successfully shown promise for hydride transfer electrocatalysis, but the reason for their high activity, and in particular the role molybdenum plays in it, remains a mystery.

A team of KAUST catalyst scientists image

(Photo source: Anastasia Serin, KAUST)

To see the molybdenum sulfide electrocatalyst in action in real-time, the researchers used a method called electron paramagnetic resonance spectroscopy (EPR). Bau adds, "To our surprise, we were able to capture it as it was happening throughout the process. We were able to capture the active state of the catalyst. Mo3+ binds directly to the hydrogen."

"The direct involvement of molybdenum ions in hydride transfer may result in better catalysts. If we can demonstrate a cohesive theory of how molybdenum is responsible for hydride transfer activity, we can focus on improving molybdenum so that it can replace platinum and also develop new molybdenum catalysts as a cheaper alternative to platinum," Bau added.

One potential use of this catalyst is to electrochemically split water molecules to produce hydrogen, which can be stored and transported as a fuel. The researchers have also demonstrated that the catalyst has great potential for improving enzymatic biocatalysts for the production of green chemicals.

Enzymes often cooperate with the naturally occurring energy-carrying molecule NADH to catalyze reactions in cells. However, the price of NADH makes it impractical for industrial biocatalysis. But molybdenum hydride produced by electrochemical methods proved to be quite effective in regenerating NADH in situ in biochemical reaction flasks.

Model of molybdenum sulfides during H2 evolution image

(Photo source: KAUST Team)

Professor Magnus Rueping from the KAUST research team said, "We were surprised by the efficiency of the process, which produces pure NADHt while avoiding by-products. Our findings of molybdenum-based catalyst open up possibilities for the realization of sustainable fuel and chemicals through enzymatic production."

Journal Reference: Bau, J. A., et al. (2022), “Mo3+ hydride as the common origin of H2 evolution and selective NADH regeneration in molybdenum sulfide electrocatalysts”. Nature Catalysis. doi:10.1038/s41929-022-00781-8.