Researchers at the U.S. Department of Energy’s Brookhaven National Laboratory may have just discovered an efficient method of converting carbon dioxide (CO2) into a usable energy. The experts have identified a new electrocatalyst that converts CO2 to carbon monoxide (CO), which is a highly energetic molecule.
“There are many ways to use CO,” said co-author Eli Stavitski. “You can react it with water to produce energy-rich hydrogen gas, or with hydrogen to produce useful chemicals, such as hydrocarbons or alcohols. If there were a sustainable, cost-efficient route to transform CO2 to CO, it would benefit society greatly.”
Using single atoms of nickel as a catalyst, the researchers achieved what scientists have been trying to accomplish for years. Previous efforts were unsuccessful because a competing reaction called the hydrogen evolution reaction (HER) was dominant over the CO2 conversion reaction.
“Nickel metal, in bulk, has rarely been selected as a promising candidate for converting CO2 to CO,” said co-author Haotian Wang. “One reason is that it performs HER very well, and brings down the CO2 reduction selectivity dramatically. Another reason is because its surface can be easily poisoned by CO molecules if any are produced.”
But now, the experts have found that single atoms of nickel produce a different result.
“Single atoms prefer to produce CO, rather than performing the competing HER, because the surface of a bulk metal is very different from individual atoms,” said Stavitski.
Co-author Klaus Attenkofer added, “The surface of a metal has one energy potential–it is uniform. Whereas on a single atom, every place on the surface has a different kind of energy.”
The CO2 conversion reaction was also facilitated by the interaction of the nickel atoms with a surrounding sheet of graphene. By anchoring the atoms to graphene, the scientists managed to adjust them and inhibit HER.
Results of the investigation revealed that single atoms of nickel catalyzed the CO2 conversion reaction with a 97 percent success rate. According to the study authors, the reliability of nickel atoms as a catalyst in this conversion process is a major step toward recycling CO2 for usable energy.
“To apply this technology to real applications in the future, we are currently aimed at producing this single atom catalyst in a cheap and large-scale way, while improving its performance and maintaining its efficiency,” said Wang.
The study is published in the journal Energy & Environmental Science.