Hydrogen from Acidic Water

Friday, February 10 2012

A technique for creating a new molecule that structurally and chemically replicates the active part of the widely used industrial catalyst molybdenite has been developed by researchers at Berkeley Lab. This technique holds promise for the creation of catalytic materials that can serve as effective low-cost alternatives to platinum for generating hydrogen gas from water that is acidic.

Christopher Chang and Jeffrey Long, chemists who hold joint appointments with Berkeley Lab and the University of California (UC) Berkeley, led a research team that synthesized a molecule to mimic the triangle-shaped molybdenum disulfide units along the edges of molybdenite crystals, which is where almost all of the catalytic activity takes place. They used a pentapyridyl ligand known as PY5Me₂ to create the molybdenum disulfide molecule. Since the bulk of molybdenite crystalline material is relatively inert from a catalytic standpoint, molecular analogs of the catalytically active edge sites could be used to make new materials that are much more efficient and cost-effective catalysts.

“Using molecular chemistry, we’ve been able to capture the functional essence of molybdenite and synthesize the smallest possible unit of its proposed catalytic active site,” says Chang. “It should now be possible to design new catalysts that have a high density of active sites so we get the same catalytic activity with much less material.”

Says Long, “Inorganic solids, such as molybdenite, are an important class of catalysts that often derive their activity from sparse active edge sites, which are structurally distinct from the inactive bulk of the molecular solid. We’ve demonstrated that it is possible to create catalytically active molecular analogs of these sites that are tailored for a specific purpose. This represents a conceptual path forward to improving future catalytic materials.”

(Berkeley Lab)