Alloy Could Produce Hydrogen Fuel Using Sunlight 360
intellitech writes "Using state-of-the-art theoretical computations, a University of Kentucky-University of Louisville team demonstrated that an alloy formed by a 2 percent substitution of antimony (Sb) in gallium nitride (GaN) has the right electrical properties to enable solar light energy to split water molecules into hydrogen and oxygen, a process known as photoelectrochemical (PEC) water splitting. When the alloy is immersed in water and exposed to sunlight, the chemical bond between the hydrogen and oxygen molecules in water is broken (abstract). Because pure hydrogen gas is not found in free abundance on Earth, it must be manufactured by unlocking it from other compounds. Thus, hydrogen is not considered an energy source, but rather an 'energy carrier.' Currently, it takes a large amount of electricity to generate hydrogen by water splitting. As a consequence, most of the hydrogen manufactured today is derived from non-renewable sources such as coal and natural gas. The team says the GaN-Sb alloy has the potential to convert solar energy into an economical, carbon-free source for hydrogen."
Re:So, no current needed? (Score:3, Interesting)
GaN is expensive (Score:5, Interesting)
Efficiency? (Score:5, Interesting)
Does the paper talk about the efficiency of this solution vs Photovoltaic panels and electrolysis? If the hydrogen and oxygen would be split over a large area (say a roof or larger), how would the gasses be collected? It sounds like an interesting result, but not so practical in application...
Re:So, no current needed? (Score:5, Interesting)
Why, particularly? I would guess that which one would be "better" would be a calculation that combines ease of access, cost, aesthetics, and ROI. Often, operations done at large scale can be done more efficiently than in a distributed fashion. Other times, the cost of distribution can offset this interent efficiency.
We don't yet know which one is "better" - the market is still merging.
One area that I'd personally love to see more solar panels is over parking lots. Nothing quite beats the misery of walking out of a nice, 75 degree mall into the blistering, 100-degree heat in the summer time, only to sit down in your 160 degree car, cursing and swearing at all that damned free energy the sun packed into your car.
But cover that parking lot with a lattice of solar panels so I'm getting into a merely hot 95 degree car while all that energy is used to power the A/C at the mall I just got out of, that would be swell.
There's also a new nickel catalyst process (Score:3, Interesting)
2 weeks ago this same source reported on research at the PNWNL [sciencedaily.com] that uses a Nickel catalyst for a 1000x improvement over the platinum catalyst process now used, for example, on the ISS.
Re:Efficiency? (Score:5, Interesting)
It sounds like an interesting result, but not so practical in application...
What's worse that this: based on the abstract [aps.org], all they did is to theoretically compute the composition required to lower the bandgap from 3.8 eV to a 2eV required to split the water. Since not yet realized in practice, lots of other things are not (yet) known:
1. efficiency (including the problem of keeping off the recombination of H and OH that most probably result)
2. stability to corrosion
would be the first two to pop into my mind.
Gallium - probably too expensive (Score:4, Interesting)
It uses gallium, which also makes great solar cells, more efficient than anything else. But the cost of gallium solar cells is so high that they're only used on spacecraft. They're about 3x more efficient than silicon solar cells, and 300x more expensive.