A team of researchers from the Lawrence Berkeley National Laboratory and the University of California, Berkeley, has discovered a catalyst metal 70 times cheaper than platinum for use in electrolysis systems, to generate hydrogen from water.
Hydrogen is by far the best fuel in the universe, but unfortunately it doesn’t exist in nature freely so it can be collected. Water, on the other hand, has plenty of hydrogen and burning that hydrogen results in having water produced again – hence its cleanliness.
“Our new proton reduction catalyst is based on a molybdenum-oxo metal complex that is about 70 times cheaper than platinum, today’s most widely used metal catalyst for splitting the water molecule,” said Hemamala Karunadasa, one of the co-discoverers of this complex. “In addition, our catalyst does not require organic additives, and can operate in neutral water, even if it is dirty, and can operate in sea water, the most abundant source of hydrogen on earth and a natural electrolyte. These qualities make our catalyst ideal for renewable energy and sustainable chemistry.”
The molybdenum-oxo complex that Karunadasa, Chang and Long discovered is a high valence metal with the chemical name of (PY5Me2)Mo-oxo. In their studies, the research team found that this complex catalyzes the generation of hydrogen from neutral buffered water or even sea water with a turnover frequency of 2.4 moles of hydrogen per mole of catalyst per second.
Jeffrey Long, a co-author of the paper describing their work, says, “This metal-oxo complex represents a distinct molecular motif for reduction catalysis that has high activity and stability in water. We are now focused on modifying the PY5Me ligand portion of the complex and investigating other metal complexes based on similar ligand platforms to further facilitate electrical charge-driven as well as light-driven catalytic processes. Our particular emphasis is on chemistry relevant to sustainable energy cycles.”
Plants also dissociate water during photosynthesis, through a process called “hydrogenase”. This one, though, is hard to mimic technologically and the enzymes involved are unstable and easily deactivated when removed from their native environment. Platinum costs some $2,000 an ounce, and that is the reason fuel cells are so expensive. Finding a cheap water splitting catalyst would greatly increase the chances that fuel cells will survive through time.