Sunlight and wastewater nitrate to make ammonia

Engineers have created a solar-powered electrochemical reaction that not only uses wastewater to make ammonia—the second most-produced chemical in the world—but also achieves a solar-to-fuel efficiency that is 10 times better than any other comparable technology.

This technology has great potential for allowing on-demand synthesis of fertilizers and many manufactured products, like pharmaceuticals, and plastics, and on efforts to reduce greenhouse gases from fossil fuels.

Researchers have used nitrate, one of the most common groundwater contaminants, to supply Nitrogen and sunlight to electrify the reaction.

The system produces nearly 100% ammonia with nearly zero Hydrogen gas side reactions. The reaction needs no fossil fuels and produces no Carbon dioxide or other greenhouse gases, and it use the solar power.

The new method hinges on a cobalt catalyst, which is found that a rough Cobalt surface derived from oxidation worked best to create a reaction that was selective, meaning it converted nearly all the nitrate molecules to ammonia.

The process may simultaneously help correct for industrial waste and runoff water and rebalance the Nitrogen cycle, particularly in rural areas which may experience economic disadvantages or bear the greatest risk from high exposure to excess nitrate.