25 July 2020
A solid approach to carbon recycling
Published online 2 September 2019
Efficient conversion of carbon dioxide into pure liquid fuels can be achieved by using solid electrolytes, instead of liquid.
The ability to convert carbon dioxide (CO2) back into valuable fuels using renewable energy could lead to a sustainable, carbon-neutral energy cycle. However, industry requires new methods of electrocatalysis to achieve such complicated CO2 reduction reactions in an energy-efficient manner. Researchers in the USA and Saudi Arabia have demonstrated a promising approach that uses solid electrolytes in place of liquids.
Liquid electrolyte systems are well established for CO2 reduction, but the resulting liquid fuels tend to be mixed with salts, which must be separated via further energy-intensive processes. Inspired by recent developments in solid-state batteries, a team of researchers, led by Haotian Wang at Rice University in the USA, chose to investigate the potential of solid electrolytes to produce pure products from CO2.
They showed that their electrocatalytic system, containing a solid bismuth catalyst, could continuously convert CO2 into pure, highly concentrated formic acid for more than 100 hours with no degradation in the catalyst. They then incorporated a copper catalyst in their system to produce other electrolyte-free fuels including acetic acid, ethanol and n-propanol.
“Given the wide variety of solid electrolytes available, we expect the approach could be extended to the production of other liquid fuels, and to other electrocatalytic reactions,” says Wang’s postdoctoral researcher, Chuan Xia, who wrote the team’s paper published in Nature Energy. “This may shift the current energy and chemical industry away from fossil fuel dependence into renewable sources like solar and wind.”
Xia, C. et al. Continuous production of pure liquid fuel solutions via electrocatalytic CO2 reduction using solid-electrolyte devices. Nat. Energy https://doi.org/10.1038/s41560-019-0451-x (2019).