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 (COad) intermediates on active sites, which is conducive to C-C coupling or further reaction. The presence of hydroxyl adsorbates (OHad) changes the charge distribution on the catalyst surface and reduces the energy barrier of C-C coupling. However, the excessive OHad adsorption can occupy a large number of active sites, leading to a decrease in COad coverage. We unveiled that the combined co-acting effect of potassium ions and hydroxide ions co-regulated the COad adsorption energy and COad 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.