Rational Construction of Co₄(μ-O)₆(COO)₆ SBU-Based MOFs through Mixed-Ligand Strategy to Enhance Electrocatalytic Oxygen Evolution Performance

Metal-organic frameworks (MOFs) are increasingly becoming an important choice for developing robust and efficient electrocatalysts; therefore, exploring the relationship between the structure, catalytic activity, and stability of MOFs is of great significance. MOFs <b>1</b>-<b>3</b> with different spatial configurations are designed and synthesized based on linear pyridine ligands, tetragonal carboxylic acid ligands, and triangular carboxylic acid ligands, while MOF <b>4</b> displays a three-dimensional (3D) supramolecule assembled through a mixed-ligand strategy. Compared with MOFs <b>1</b>-<b>3</b>, MOF <b>4</b> has the lowest overpotential of 106 mV (at 10 mA·cm^-2) and a Tafel slope of 80.9 mV·dec^-1, as well as sturdy long-term stability in the process of oxygen evolution reaction (OER). The presence of dense metal clusters and μ₃-O promotes the optimal catalytic performance of MOF <b>4</b>. Density functional theory (DFT) calculations of MOF <b>4</b> demonstrate that the process from O* to OOH* is the rate-determining step. This investigation further reveals the relationship between MOF structural composition and electrocatalytic OER performance and provides an effective strategy for the assembly of MOF-based electrocatalysts.