Low coordination number copper catalysts for electrochemical CO<sub>2</sub> methanation in a membrane electrode assembly.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34006871.
- Also identified by DOI 10.1038/s41467-021-23065-4 and PMC identifier 8131708.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The electrochemical conversion of CO<sub>2</sub> to methane provides a means to store intermittent renewable electricity in the form of a carbon-neutral hydrocarbon fuel that benefits from an established global distribution network. The stability and selectivity of reported approaches reside below technoeconomic-related requirements. Membrane electrode assembly-based reactors offer a known path to stability; however, highly alkaline conditions on the cathode favour C-C coupling and multi-carbon products. In computational studies herein, we find that copper in a low coordination number favours methane even under highly alkaline conditions. Experimentally, we develop a carbon nanoparticle moderator strategy that confines a copper-complex catalyst when employed in a membrane electrode assembly. In-situ XAS measurements confirm that increased carbon nanoparticle loadings can reduce the metallic copper coordination number. At a copper coordination number of 4.2 we demonstrate a CO<sub>2</sub>-to-methane selectivity of 62%, a methane partial current density of 136 mA cm<sup>-2</sup>, and > 110 hours of stable operation.