Operando Raman spectroscopy uncovers hydroxide and CO species enhance ethanol selectivity during pulsed CO<sub>2</sub> electroreduction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38734726.
- Also identified by DOI 10.1038/s41467-024-48052-3 and PMC identifier 11088695.
- 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
Pulsed CO<sub>2</sub> electroreduction (CO<sub>2</sub>RR) has recently emerged as a facile way to in situ tune the product selectivity, in particular toward ethanol, without re-designing the catalytic system. However, in-depth mechanistic understanding requires comprehensive operando time-resolved studies to identify the kinetics and dynamics of the electrocatalytic interface. Here, we track the adsorbates and the catalyst state of pre-reduced Cu<sub>2</sub>O nanocubes ( ~ 30 nm) during pulsed CO<sub>2</sub>RR using sub-second time-resolved operando Raman spectroscopy. By screening a variety of product-steering pulse length conditions, we unravel the critical role of co-adsorbed OH and CO on the Cu surface next to the oxidative formation of Cu-O<sub>ad</sub> or CuO<sub>x</sub>/(OH)<sub>y</sub> species, impacting the kinetics of CO adsorption and boosting the ethanol selectivity. However, a too low OH<sub>ad</sub> coverage following the formation of bulk-like Cu<sub>2</sub>O induces a significant increase in the C<sub>1</sub> selectivity, while a too high OH<sub>ad</sub> coverage poisons the surface for C-C coupling. Thus, we unveil the importance of co-adsorbed OH on the alcohol formation under CO<sub>2</sub>RR conditions and thereby, pave the way for improved catalyst design and operating conditions.