skip to content

CARES

 

eCO₂EP project leaders publish a perspective on the electrochemical synthesis of bulk intermediates from carbon dioxide

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).

 

Dinh et al. show that the use of very thin copper-catalyst layers in a gas diffusion electrode leads to efficient and selective electrochemical conversion of CO₂ to ethylene. Such a process could help to mitigate rising atmospheric CO₂ concentrations if the energy required for the conversion comes from renewable sources.

 

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 CO₂. 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 minimising 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 CO₂ conversion, but significant challenges remain. Separation of the product gases from the CO₂ feed (and/or liquid products from the electrolyte) has not yet been demonstrated. More globally, a cost-effective source of CO₂ would need to be identified.

Electrochemical conversion of CO₂ 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 eCO2EP project. 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 “CO₂ recycling technology” (Perathoner, S. and Centi, G. (2014) CO₂ recycling: a key strategy to introduce green energy in the chemical production chain. ChemSusChem, 7, 12741282).