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Alloy Could Produce Hydrogen Fuel Using Sunlight
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."
Gallium nitride (GaN) is used to make blue LED chips, typically vacuum deposited on top of sapphire wafers. While it is a very good semiconductor, it is an order of magnitude more expensive than silicon wafers. Unless there is a huge breakthrough in mass manufacturing cheap GaN wafers, it will be much cheaper to use silicon solar cells to generate electricity and electrolyze water with it.
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...
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