Synergistic Effect of Metal Doping and Tethered Ligand Promoted High-Selectivity Conversion of CO₂ to C₂ Oxygenates at Ultra-Low Potential

Effectively controlling the selectivity of C₂ oxygenates is desirable for electrocatalytic CO₂ reduction. Copper catalyst has been considered as the most potential for reducing CO₂ to C₂ products, but it still suffers from low C₂ selectivity, high overpotential, and competitive hydrogen evolution reaction (HER). Here, we propose a design strategy to introduce a second metal that weakly binds to H and a functional ligand that provides hydrogen bonds and protons to achieve high selectivity of C₂ oxygenates and effective suppression of HER on the Cu(100) surface simultaneously. Seven metals and eleven ligands are screened using first-principles calculations, which shows that Sn is the most efficient for inhibiting HER and cysteamine (CYS) ligand is the most significant in reducing the limiting potential of ^*CO hydrogenation to ^*CHO. In the post C−C coupling steps, a so-called “pulling effect” that transfers H in the CYS ligand as a viable proton donor to the C₂ intermediate to form an H bond, can further stabilize the OH group and facilitate the selection of C₂ products toward oxygenates. Therefore, this heterogeneous electrocatalyst can effectively reduce CO₂ to ethanol and ethylene glycol with an ultra-low limiting potential of −0.43 V. This study provides a new strategy for effectively improving the selectivity of C₂ oxygenates and inhibiting HER to achieve advanced electrocatalytic CO₂ reduction.