Direct Cation Stabilization Effects of CO Dimerization for Boosting C₂ Pathways of CO₂ Reduction on Noble Metal Surfaces

The carbon dioxide reduction reaction (CO₂RR) is one of the most promising solutions for realizing carbon neutralization via converting the emitted CO₂ into value-added chemicals. The C-C coupling step for CO dimerization is the rate-determining step for C₂ pathways, which have not been thoroughly investigated. Herein, the direct cation stabilization effects on CO dimerization for *OCCO formation on the representative Cu(100) and Pt(100) surfaces are investigated. Density functional theory calculations show that the presence of alkali metal ions plays a vital role in promoting the coupling of *CO monomers on both metal surfaces, where Cu shows a stronger stabilization effect. More importantly, a strong linear correlation (R² ≈ 0.9) between the dimer stabilization energy and the reaction energy is revealed for the first time, which is a promising indicator for the selectivity of C₂ pathways. Further investigations on electronic structures reveal that the promoting effect on *OCCO formation is strongly related to the negative charges of the molecules, in which the negative charge accumulation is favored by the directional electron transfer due to the chemisorption of *OCCO on Cu(100) surface. This work offers insights into the understanding of C-C coupling reactions for CO₂RR mechanisms.