Selective C-C Coupling by Spatially Confined Dimeric Metal Centers

Direct conversion of carbon dioxide (CO₂) to high-energy fuels and high-value chemicals is a fascinating sustainable strategy. For most of the current electrocatalysts for CO₂ reduction, however, multi-carbon products are inhibited by large overpotentials and low selectivity. Herein, we exploit dispersed 3d transition metal dimers as spatially confined dual reaction centers for selective reduction of CO₂ to liquid fuels. Various nitrogenated holey carbon monolayers are shown to be promising templates to stabilize these metal dimers and dictate their electronic structures, allowing precise control of the catalytic activity and product selectivity. By comprehensive first-principles calculations, we screen the suitable transition metal dimers that universally have high activity for ethanol (C₂H₅OH). Furthermore, remarkable selectivity for C₂H₅OH against other C₁ and C₂ products is found for Fe₂ dimer anchored on C₂N monolayer. The role of electronic coupling between the metal dimer and the carbon substrates is thoroughly elucidated.