Researchers at the Oak Ridge National Laboratory have successfully converted carbon dioxide, a greenhouse gas, into ethanol using nanotechnology.
The scientists developed an electrochemical process that uses tiny spikes of carbon and copper to convert carbon dioxide into ethanol. Adam Rondinone, lead author of the study, said the original intent of the experiment was to produce methanol and not ethanol.
“We discovered somewhat by accident that this material worked,” Rondinone said in a statement. “We were trying to study the first step of a proposed reaction when we realized that the catalyst was doing the entire reaction on its own.”
The team was able to apply voltage to a catalyst made of carbon, copper and nitrogen to trigger a chemical reaction that essentially reverses the combustion process.
The catalyst used consisted of copper nanoparticles embedded in carbon spikes, which avoids the use of expensive or rare metals like platinum that often make many catalysts economically impractical.
“By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want,” Rondinone added. “They are like 50-nanometer lightning rods that concentrate electrochemical reactivity at the tip of the spike.”
With the help of the catalyst, which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent.
“We’re taking carbon dioxide, a waste product of combustion and we’re pushing that combustion reaction backwards with very high selectivity to a useful fuel,” Rondinone said. “Ethanol was a surprise—it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.”
Along with the technique being relatively cheap, it also can operate at room temperature in water, meaning it can be “turned on and off” without much additional energy wasted.
With that in mind, the researchers believe the approach could be scaled up for industrially relevant applications. For example, the process could be used to store excess electricity generated from variable power sources like wind and solar.
Ethanol is used in a variety of products including, antibacterial hand sanitizer gels, as an antidote for methanol, alcoholic beverages, engine fuel and rocket fuel.
Along with Rondinone, the study was co-authored by ORNL’s Yang Song, Rui Peng, Dale Hensley, Peter Bonnesen, Liangbo Liang, Zili Wu, Harry Meyer III, Miaofang Chi, Cheng Ma and Bobby Sumpter. The study, which is published as “High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode” can be viewed here.