Nitrogen is an ubiquitous small-molecule gas that can be transformed into the agricultural fertiliser ammonia. Plants perform the chemical reduction of atmospheric nitrogen to ammonia as a matter of course, but for humans to do that in an industrial setting requires subjecting nitrogen to massive amounts of energy under high pressure. "The current process for reducing nitrogen to ammonia is done under extreme conditions", says Robert J. Hamers with reference to the so-called
Haber-Bosch process. "There is an enormous barrier you have to overcome to get your final product". Hamers is professor of chemistry at the
University of Wisconsin-Madison.
Breaching that barrier more efficiently and reducing the huge amounts of energy used to convert nitrogen to ammonia - by some estimates, 2 percent of the world’s electrical output - has been a grail for the agricultural chemical industry. Now, that goal may be on the horizon, thanks to a technique devised by Hamers and his colleagues and published in the journal Nature Methods.
Like all chemical reactions, the reduction of nitrogen to ammonia involves moving electrons from one molecule to another. Using hydrogen-coated diamond illuminated by deep ultraviolet light, the Wisconsin team was able to induce a ready stream of electrons into water, which served as a reactant liquid that reduced nitrogen to ammonia under temperature and pressure conditions far more efficient than those required by traditional industrial methods. So, diamond can facilitate the reduction of nitrogen to ammonia under ambient temperatures and pressures.
The technique devised by Hamers and his colleagues, he notes, still has kinks that need to be worked out to make it a viable alternative to traditional methods. The use of deep ultraviolet light, for example, is a limiting factor.
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Source: University of Wisconsin-Madison