Researchers in Switzerland have developed a catalyst to encourage solar-driven electrochemical reduction of CO2 to fuels and chemicals, a development that could help close the anthropogenic carbon cycle.
Electrolysis can be used to split carbon dioxide into oxygen and carbon monoxide, which can then be transformed into liquid fuels. Current CO-forming catalysts, however, are either not selective enough or too expensive to be industrially viable.
Now, scientists at EPFL have developed an Earth-abundant catalyst based on copper-oxide nanowires modified with tin oxide.
A solar-driven system set up using this catalyst was able to split CO2 with an efficiency of 13.4 per cent. The work is published in Nature Energy, and is expected to help efforts to synthetically produce carbon-based fuels from CO2 and water.
The catalyst, developed by PhD student Marcel Schreier and colleagues, is made by depositing atomic layers of tin oxide on copper oxide nanowires. Tin oxide is said to suppress the generation of side-products, which are commonly observed from copper oxide catalysts, leading to the sole production of CO in the electroreduction of CO2.
According to EPFL, the catalyst was integrated into a CO2 electrolysis system and linked to a triple-junction solar cell (GaInP/GaInAs/Ge) to make a CO2 photo-electrolyser.
The system uses the same catalyst as the cathode that reduces CO2 to CO and the anode that oxidises water to oxygen through a process called oxygen evolution reaction. The gases are separated with a bipolar membrane.
The system was able to selectively convert CO2 to CO with an efficiency of 13.4 per cent using solar energy. The catalyst also reached a Faradaic efficiency of up to 90 per cent.
“This is the first time that such a bi-functional and low-cost catalyst is demonstrated,” Schreier said in a statement. “Very few catalysts – except expensive ones, like gold and silver – can selectively transform CO2 to CO in water, which is crucial for industrial applications.”