Tricycloquinazoline-Based 2D Conductive Metal-Organic Frameworks as Promising Electrocatalysts for CO₂ Reduction

2D conductive metal-organic frameworks (2D c-MOFs) are promising candidates for efficient electrocatalysts for the CO₂ reduction reaction (CO₂ RR). A nitrogen-rich tricycloquinazoline (TQ) based multitopic catechol ligand was used to coordinate with transition-metal ions (Cu²⁺ and Ni²⁺ ), which formed 2D graphene-like porous sheets: M₃ (HHTQ)₂ (M=Cu, Ni; HHTQ=2,3,7,8,12,13-Hexahydroxytricycloquinazoline). M₃ (HHTQ)₂ can be regarded as a single-atom catalyst where Cu or Ni centers are uniformly distributed in the hexagonal lattices. Cu₃ (HHTQ)₂ exhibited superior catalytic activity towards CO₂ RR in which CH₃ OH is the sole product. The Faradic efficiency of CH₃ OH reached up to 53.6 % at a small over-potential of -0.4 V. Cu₃ (HHTQ)₂ exhibited larger CO₂ adsorption energies and higher activities over the isostructural Ni₃ (HHTQ)₂ and the reported archetypical Cu₃ (HHTP)₂ . There is a strong dependence of both metal centers and the N-rich ligands on the electrocatalytic performance.