Understanding the CO₂ Reduction Selectivity toward Ethanol on Single Atom Doped Cu/Cu₂O Catalysts: Insights from Bader Charge as a Descriptor

In the CO₂ reduction reactions (CO₂RR), the product selectivity is strongly dependent on the binding energy differences of the key intermediates. Herein, we systematically evaluated the CO₂RR reaction pathways on single transition metal atom doped catalysts TM₁Cu/Cu₂O by density functional theory (DFT) methods and found that *CO is more likely to undergo C-O bond cleavage rather than be hydrogenated on TM₁Cu/Cu₂O (TM = Sc, Ti, V, Cr, Mn, Fe, Co), which facilitates C₂₊ production with a low-energy pathway of OC-C coupling, while it prefers to be hydrogenated to form CHO on TM₁Cu/Cu₂O (TM = Ni, Cu). The defects of Cu in TM₁Cu/Cu₂O were confirmed to enhance the production of ethanol. Furthermore, we established a scaling relationship between binding free energies of the key intermediates with the Bader charges of the active sites TM on TM₁Cu/Cu₂O and defective TM₁Cu/Cu₂O surfaces. This relationship facilitates a rational and efficient design of Cu/Cu₂O-based catalysts.