Year: 2026
Type: preprint
Abstract: Cation effect is essential to obtain selectivity towards carbon dioxide (CO 2 ) reduction reaction (CO 2 RR) over the hydrogen evolution reaction (HER) in acidic media. Selectivity towards CO 2 RR has been largely attributed to the coordination between alkali cations and CO 2 -derived intermediates. Here, we provide a different perspective by demonstrating that tetraethylammonium (Et 4 N + ), a weakly coordinating cation, can also effectively suppress the HER in acidic media, favoring CO 2 RR on both Ag and Cu electrodes. The generation of both C 1 and C 2+ products on Cu indicates that the direct participation of alkali cations as co-catalyst is not a prerequisite for CO 2 activation or C-C coupling. We find that CO 2 RR is independent of the bulk pH in the presence of 1 M Et 4 N + , as evidenced by similar selectivity across acidic, neutral, and alkaline media. In addition, rigorous impurities control reveals that millimolar-levels of triethylammonium chloride (Et 3 NHCl) substantially promote HER on Cu catalyst, hence calling for careful impurity control. Overall, this work reveals the use of Et 4 N + as an valuable platform to investigate the effects of cations or impurities for CO 2 RR.
Source: ChemRxiv
Institution: École Polytechnique Fédérale de Lausanne
Language: English
Field: Energy
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W7213223189