Sometimes one single thing makes the difference. For example, in the race to find alternative sources of energy, especially for transportation, hydrogen is seen as a potentially major source of fuel. Hydrogen is abundant in nature. It has a high energy output. It ‘burns’ cleanly. For most fuel cell and engine applications, hydrogen is created by catalyzing water, splitting water into its component elements H (hydrogen) and O (Oxygen). Therein lies a problem – the catalyst. The catalyst in this case is the material that when combined with electricity or some other chemical agent, facilities the breaking of the bonds between hydrogen and oxygen in water. Most common catalysts for the job are expensive, and the best – platinum – is very expensive. In laboratory tests or small scale demonstrations, using an expensive catalyst such as platinum is a relatively small item. But for hydrogen to be a serious contender as an alternative energy source, that’s talking global use and vast quantities. At that scale, the cost of the catalyst is very significant, even a deal-breaker.
That’s why a discovery by the U.S. Department of Energy Lawrence Berkeley National Laboratory (Berkeley Lab) of an inexpensive metallic catalyst could be very important.
The catalyst uses molybdenum, a relatively common and therefore relatively inexpensive metallic element. The key discovery was the precise form for molybdenum, called a molybdenum-oxo complex. Technically this is a high valence (bonding capacity) metal with the chemical name (PY5Me2)Mo-oxo, in short a complex molecule based on molybdenum. Because of its complex structure, this catalyst does not need additional acids or organic co-solvents to function. In fact, it can perform quite well in neutral buffered water, dirty water, and even sea water.
“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.”
[Source: Berkeley Labs]
Indeed, this catalyst is almost ideal. The IF part of this, however, is the long term stability of the catalyst; it may be very good but if it has to be replaced frequently, that could negate its cost advantage. The researchers indicate that more work is necessary on the ligand portion (the PY5Me2), the complex attached to the molybdenum, to make it more stable – without losing the reactive capability.
Is this, then, the missing piece from the final industrial production of hydrogen from water? Possibly; but it probably has a way to go from the lab to the production line. On the other hand, if it works well enough, adoption will come quickly and you’ll be hearing about new fuel cells that use it within a year or two.