Researchers have discovered a highly effective way of converting carbon dioxide, the most common greenhouse gas in Earth\'s atmosphere, into ethanol, an important industrial chemical that is used as a solvent in the synthesis of other organic chemicals, and as an additive to automotive gasoline.
Artistic rendering of electrocatalytic process for conversion of carbon dioxide and water into ethanol. Photo: Image by Argonne National Laboratory
A team of researchers, led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory in collaboration with Northern Illinois University, has discovered a new electrocatalyst that converts carbon dioxide (CO2) and water into ethanol with very high energy efficiency and selectivity for the desired final product and low cost.
The report on the discovery, first made in an NIU laboratory and studied in detail at Argonne, has been published in the scientific journal Nature Energy.
“With this research, we’ve discovered a new catalytic mechanism for converting carbon dioxide and water into ethanol,” said author Tao Xu, a professor in physical chemistry and nanotechnology from Northern Illinois University.
“The unique synthetic method for production of electrocatalysts developed in our NIU lab enables a crucial dynamic interaction between the catalytic metal atoms and the carbon substrate that can efficiently orientate the electrochemical reaction to produce a range of desired organic fuels,” he added.
Catalysts speed up chemical reactions and form the backbone of many industrial processes. They are essential in transforming heavy oil into gasoline or jet fuel.
At present, catalysts are involved in over 80 percent of all manufactured products.
The new catalyst consists of atomically dispersed copper on a carbon-powder support. It breaks down carbon dioxide and water molecules and selectively reassembles them into ethanol using an external electrical field.
The electrocatalytic selectivity, or “Faradaic efficiency,” of the process is over 90 percent, much higher than any other reported process. It can also operate stably over extended operation at low voltage.
“The process resulting from our catalyst would contribute to the circular carbon economy, which entails the reuse of carbon dioxide,” said study co-author and Argonne senior chemist Di-Jia Liu.
Because CO2 is a stable molecule, transforming it into a different molecule is normally energy intensive and costly.
However, according to Liu, “We could couple the electrochemical process of CO2-to-ethanol conversion using our catalyst to the electric grid and take advantage of the low-cost electricity available from renewable sources like solar and wind during off-peak hours.”
Because the process runs at low temperature and pressure, it can start and stop rapidly in response to the intermittent supply of the renewable electricity, the researchers said.
The research team took advantage of two DOE Office of Science User Facilities at Argonne — the Advanced Photon Source (APS) and Center for Nanoscale Materials (CNM) — as well as Argonne’s Laboratory Computing Resource Center (LCRC).
“Thanks to the high photon flux of the X-ray beams at the APS, we have captured the structural changes of the catalyst during the electrochemical reaction,’’ said co-author Tao Li, an assistant professor in the Department of Chemistry and Biochemistry at NIU and an assistant scientist in Argonne’s X-ray Science division.
The researchers emphasize the finding can shed light on ways to further improve the catalyst through rational design.
“We have prepared several new catalysts using this approach and found that they are all highly efficient in converting CO2 to other hydrocarbons,” said Liu. “We plan to continue this research in collaboration with industry to advance this promising technology.”
The research was supported by Argonne’s Laboratory Directed Research and Development (LDRD) fund provided by the DOE Office of Science and the DOE Office of Basic Energy Sciences.