pH effects on the electrochemical reduction of CO<sub>(2)</sub> towards C<sub>2</sub> products on stepped copper.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30604776.
- Also identified by DOI 10.1038/s41467-018-07970-9 and PMC identifier 6318338.
- 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
We present a microkinetic model for CO<sub>(2)</sub> reduction (CO<sub>(2)</sub>R) on Cu(211) towards C<sub>2</sub> products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C<sub>1</sub> vs C<sub>2</sub> activity arise from differences in their multi-step mechanisms. We find the depletion in C<sub>2</sub> products observed at high overpotential and high pH to arise from the 2<sup>nd</sup> order dependence of C-C coupling on CO coverage, which decreases due to competition from the C<sub>1</sub> pathway. We further demonstrate that CO<sub>(2)</sub> reduction at a fixed pH yield similar activities, due to the facile kinetics for CO<sub>2</sub> reduction to CO on Cu, which suggests C<sub>2</sub> products to be favored for CO<sub>2</sub>R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C<sub>2</sub> products.