Directional Design of the Pyridine Ligand Functional Block to Improve the Electrocatalytic Nitrate Reduction Performance of the Co-MOFs

The electrocatalytic nitrate reduction reaction (NITRR) holds great promise for producing high-value-added ammonia (NH₃). The development of highly efficient catalysts will be one of the key factors for achieving nitrate reduction to synthesize ammonia. In this study, three cobalt-based metal-organic frameworks (Co-MOFs) based on different ligands with varying electron-donating properties (bpta = 3,5-bis(4-pyridyl)-1,2,4-triazolyl, bpt = 2,5-bis(4-pyridyl)-1,3,4-thiadiazole, dpb = 4-di(4-pyridyl)benzene) are synthesized. Experimental results demonstrate that the Co-bpta-btc exhibits the highest NITRR activity, achieving an NH₃ yield of up to 10.3 mg h^-1 mg_cat^-1 (at -1.0 V vs RHE) and a Faradaic efficiency (FEs) of 83.3% (at -0.8 V vs RHE). The enhanced performance can be attributed to stronger electronic interactions and improved charge transfer capabilities facilitated by the electron-donating nature of the bpta ligand. This work enhances the catalytic activity of the electrocatalyst by adjusting the organic ligands, providing a new idea for designing green and efficient catalysts for electrochemical nitrogen reduction reactions.