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 C-2 oxygenates is desirable for electrocatalytic CO2 reduction. Copper catalyst has been considered as the most potential for reducing CO2 to C-2 products, but it still suffers from low C-2 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 C-2 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 C-2 intermediate to form an H bond, can further stabilize the OH group and facilitate the selection of C-2 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 C-2 oxygenates and inhibiting HER to achieve advanced electrocatalytic CO2 reduction.

Automated summary

By introducing a second metal and a functional ligand, a design strategy is proposed to achieve high selectivity of C-2 oxygenates and effectively inhibit the HER on the Cu(100) surface. This approach provides a new method to improve the electrocatalytic reduction of CO2.