In the 18th of May issue of Science, the Professors Joel Ager (Lawrence Berkeley National Laboratory and Department of Materials Science and Engineering, University of California Berkeley) and Alexei Lapkin (Department of Chemical Engineering and Biotechnology, University of Cambridge) outlined their perspective on the prospects of using excess renewable grid electricity to convert carbon dioxide into commodity chemicals (DOI: 10.1126/science.aat7918).

The perspective was motivated by the report from the research group of Edward H. Sargent (University of Toronto), in the same issue, of an important breakthrough in the electrocatalytic conversion of carbon dioxide to ethylene (DOI: 10.1126/science.aas9100). The group was able to achieve a large increase in the rate of ethylene production, while retaining a high degree of selectivity, by maintaining optimal reaction conditions in a thin region with a high concentration of the reactant CO 2 . In this cell structure a very thin layer of copper catalyst was sandwiched between a highly basic electrolyte and a non-wetting gas diffusion electrode, such that the rate of carbon dioxide feed to the catalyst was commensurate with the rate of its consumption. As a result, the highly basic conditions favourable for ethylene were maintained while minimizing potential side reactions of carbon dioxide with the basic electrolyte.

The advance reported by the group of Sargent is an important step forward in the design of the electrochemical system for CO 2 conversion, but significant challenges remain. Separation of the product gases from the CO 2 feed (and/or liquid products from the electrolyte) has not yet been demonstrated. More globally, a cost-effective source of CO 2 would need to be identified.

Electrochemical conversion of CO 2 into ethylene and 1-propanol is the topic of the joint project between the Singapore research centres of the University of California Berkeley and University of Cambridge with National University of Singapore and Nanyang Technological University, the eCO 2 EP project (www.cares.cam.ac.uk/eco2ep). In this project the international team of investigators is attempting, for the first time, to scale this technology to a demonstration facility, and to solve the issues of integration of the individual elements: two electrocatalysts and product separation. This technology is seen as a likely future route to bulk chemical products under the scenario of large-scale use of renewable energy, known as “CO 2 recycling technology” (Perathoner, S. and Centi, G. (2014) CO 2 recycling: a key strategy to introduce green energy in the chemical production chain. ChemSusChem, 7, 1274–1282.)