Exploring Ligand-Controlled C₂ Product Selectivity in Carbon Dioxide Reduction with Copper Metal–Organic Framework Nanosheets

The suitable choice of an electrocatalyst is crucial in controlling the selectivity of electrocatalytic CO₂ reduction products. Herein, we have explored the effect of different ligand environments in 2D metal-organic frameworks (MOFs), viz., copper naphthalenedicarboxylate (Cu-UNDC) and copper benzenedicarboxylate (Cu-UBDC). The change of ligand modulates the structure of the MOFs as well as the electronic environment around the copper center. The variation in the electronic structure and the coordination environment of the active Cu center changes the selectivity toward C₂ products. In the electrocatalytic process, Cu-UNDC produced 24.3% Faradaic efficiency (FE) for the C₂ products─far better than that of Cu-UBDC (13.2%). In contrast to electrocatalytic CO₂RR, in the presence of light, Cu-UBDC (26.2%) achieved a better FE for the C₂ products than Cu-UNDC (21.8%).