A team of scientists from the University of Colorado Boulder and the US Department of Energy’s National Renewable Energy Laboratory (NREL) created fertiliser from sunlight in the hopes of improving agricultural practices and reducing the use of fossil fuels. Their study published on April 22 in the journal Science states that they used light energy to create ammonia, the main ingredient of fertilisers.
The key to harvesting light was combining the semiconductor nanocrystals of the compound cadmium sulphide with nitrogenase, a catalyst. These energise the sunlight’s electrons to transform the dinotrogen, a molecule made of two nitrogen atoms, into ammonia.
“Using light harvesting to drive difficult catalytic reactions has the potential to create new, more efficient chemical and fuel production technologies,” adds researcher Katherine Brown, a research scientist at NREL. “This new ammonia-producing process is the first example of how light energy can be directly coupled to enzymatic N2 (dinitrogen) reduction, meaning sunlight or artificial light can power the reaction.”
The researchers’ method is another way to convert nitrogen to be used by plants and animals. One entails a biological process where the most common gas in Earth’s atmosphere is secured by bacteria in the roots of several plants such as legumes. The nitrogenase then converts nitrogen into ammonia.
Another method is called the Haber-Bosch process. Apparently, it was an approach developed a century ago that transforms the dinitrogen into ammonia in a complicated process that involves very high heat and high pressures. However, this old method does more harm than good because it uses a lot of fossil fuels, subsequently releasing greenhouse gases that contribute to climate change.
The researchers believe that the discovery of the light-driven chemical process will transform the future for the better. They hope that the method will pave the way for improvements in current global agricultural techniques and lower reliance on fossil fuels.