The Potential of Cations for Carbon Dioxide Electroreduction

The electrochemical reduction of carbon dioxide (eCO2R) allows both the reduction of anthropogenic greenhouse gas emissions and the storage of intermittent renewable energy. While modeling studies have focused on the catalyst for at least two decades, recently the electrolyte–electrode interface has attracted significant attention, especially metal cations. In this Perspective, we propose simple rules to predict the extent of cation effects on eCO2R and water reduction depending on the transition metal catalyst, which we later extend to the case of alkali cation-induced surface dissolution. First, we highlight the difficulty of activating (eCO2R) and the crucial boost that cations provide for late transition metals. Then we re-interpret state-of-the-art results in terms of a unique descriptor, i.e., cation-induced electrostatic potential. Finally, we suggest a possible qualitative explanation for cation effects in cathodic dissolution and mention strategies to overcome cation-induced salt formation. The final Outlook lists directions that the modeling field should follow, i.e., either simplicity (Computational Cation Electrode) or complexity (Multiscale models), showing the potential of simulations toward the understanding of novel electrochemical processes (i.e., eCO2R in organic cations).