2D Undulated Metal Hydrogen-Bonded Organic Frameworks with Self-Adaption Interlayered Sites for Highly Efficient C–C Coupling in the Electrocatalytic CO₂ Reduction

Highly crystalline 2D metal hydrogen-bonded organic frameworks (2D-M-HOFs) including 2D-Cu-HOF and 2D-Ni-HOF were designed and synthesized. The 2D-M-HOF with flexible ligands leads to the formation of the self-adaption interlayered sites, which facilitate the C–C couple and overcome the limitations of the coadsorption of multiple intermediates in the electrocatalytic CO₂ reduction reaction. The undulated 2D-Cu-HOF exhibits outstanding activity and selectivity for electrocatalytic reduction of CO₂ to C₂ products with a total Faradaic efficiency of 82.1% (48.2% for C₂H₅OH and 33.9% for C₂H₄) at −1.2 V vs. RHE.