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.
Keywords: CO2RR; conductivity; electrocatalysis; metal-organic frameworks; methanol.
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