Using solar-powered diamonds to turn CO2 into useful materials

German-based researchers believe that lab-grown diamonds are a good candidate for carbon capture, and might even turn air into fertiliser.

The researchers have shown that diamonds can use light to provoke chemical reactions. The process they are using requires much less energy than conventional reactions.

“These results are a great cause for optimism,” says lead author Dr Arsène Chemin, a postdoctoral researcher at the Helmholtz-Zentrum Berlin für Materialien und Energie, Germany.

“With diamond materials we have a new class of materials that can be explored and widely used.”

When provoked by the right type of light, diamonds can emit “solvated electrons”: free individual electrons in a liquid (or solution). These tiny particles are very good at performing a chemical reaction called “reduction”.

This is important, because turning CO2 into other substances (like methanol) is a reduction reaction, as is turning the nitrogen in the air into ammonia fertiliser.

In water, diamonds perform the opposite of the reduction reaction, called oxidation, meaning that reduction should be off the cards. Plus, the reaction was thought to need a higher energy light than visible light, like ultraviolet (UV). But previous research has shown that visible light still seemed to make diamonds release solvated electrons in water.

This research used four different chemical techniques, all types of spectroscopy, to figure out what was happening.

“Surprisingly, we found almost no difference in the photoemission of charges in liquid, regardless of whether the samples were oxidized or not,” says Chemin.

This means that diamonds can still perform reduction reactions in water. The researchers also showed that, with the right additives, they could use visible violet light to make diamonds turn CO2 into methanol, a useful industrial chemical.

While the results are highly experimental, the researchers believe they open the door to a new avenue of efficient diamond-based materials science.

The research is published in Small Methods.

Subscribe to our quarterly print magazine

Please login to favourite this article.