Unveiling co-acting effects of potassium and hydroxide ions on carbon dioxide reduction reaction selectivity

The interfacial microenvironment plays a crucial role in influencing the absorption of important reaction intermediates and the resulting selectivity for carbon dioxide reduction reaction (CO₂RR) (Xu et al., 2022) [1]. In this paper, the influence effects of potassium and hydroxide ions on CO₂RR of Cu-based catalysts are comprehensively investigated using in-situ Raman spectroscopy and theoretical calculation. The results showed that potassium ions improved the binding strength of CO adsorbates (CO_ad) intermediates on active sites, which is conducive to C-C coupling or further reaction. The presence of hydroxyl adsorbates (OH_ad) changes the charge distribution on the catalyst surface and reduces the energy barrier of C-C coupling. However, the excessive OH_ad adsorption can occupy a large number of active sites, leading to a decrease in CO_ad coverage. We unveiled that the combined co-acting effect of potassium ions and hydroxide ions co-regulated the CO_ad adsorption energy and CO_ad coverage on Cu-based catalysts, leading to the modulation of the products selectivity. This work provides new insights for understanding the effect of interfacial microenvironment on the catalytic performance of CO₂RR catalytic systems.