Monometallic dual-atom two-dimensional phthalocyanine-based metal-organic framework for carbon dioxide...

Exploring efficient catalysts is key to promoting the practical application of electrochemical CO₂ reduction reaction (CO₂RR) technology. Herein, we designed 14 types of two dimensional conjugated metal-organic frameworks (2D c-MOFs), denoted as PcM-O₈-M, featuring monometallic dual-atom centers with N₄ and O₄ coordinations, and systematically studied their CO₂RR electrocatalytic performance using density functional theory (DFT) calculations. The monometallic dual-atom centers provide a feasible method for regulating both the metal atom and the coordination environment to enhance catalytic activity. Our results reveal that these 14 PcM-O₈-M exhibit robust thermodynamic and electrochemical stability, along with good conductivity. The CO₂RR mechanism at the MN₄ and MO₄ sites in PcM-O₈-M was analyzed through free energy diagrams. The optimal active site was identified by comparing the limiting potential (U_L) of the two active sites. Four PcM-O₈-M (M = Cr, Mo, Ru, and Rh) were selected from the 14 MOFs, demonstrating high catalytic activity and selectivity toward C1 products, with the U_L ranging from -0.47 V to 0 V. Additionally, a good volcano relationship between ΔG_*COOH and U_L was established. Machine learning analysis indicates that the atomic charge of the active site is the key intrinsic factor characterizing catalytic activity. Importantly, we identified an intrinsic descriptor φ, which correlates well with U_L. This work provides valuable insights for further exploring highly efficient CO₂RR electrocatalysts.