Modulating CO2 electroreduction pathways through controlled ionomer arrangement on catalyst surfaces via solvent dispersion

Public summary

* A universal and novel approach for fine-tuning the product distribution of CO2 electroreduction is presented.

* The dispersion solvent of the catalyst ink influences ionomer configuration.

* Ionomer configuration within the catalyst layer affects the binding of intermediates in CO2 electroreduction.

* Faradaic efficiency for multicarbon products can reach 90.5% at a current density of 800 mA cm−2.

Abstract

Ionomers play a vital role in the preparation of electrodes for CO2 electroreduction, and controlling the ionomer configuration on the catalyst surface offers an effective strategy for adjusting the surface microenvironment of the electrode, thereby influencing the distribution of CO2 electroreduction products. In this study, we demonstrate that Nafion, a commonly used ionomer, exhibits distinct aggregation behaviors in solvents with different dielectric constant (ε) values. These differences in aggregation result in varied Nafion arrangements on the catalyst surface, which in turn affect the binding of ∗CO and ∗H intermediates, enabling control over product distribution. For example, over a Cu nanosheet catalyst at 800 mA cm−2, the Faradaic efficiency for multicarbon products increases from 67.5% to 90.5% simply by changing the dispersion solvent from low-ε dimethyl sulfoxide to moderate-ε isopropanol. This work introduces a novel approach for fine-tuning CO2 electroreduction product distribution through manipulation of the dispersion solvent without requiring modifications to the catalyst or ionomer.