The effect of replacing linker with carboxylic acid ligands on the oxygen evolution performance of metal-organic frameworks

Metal-organic frameworks (MOFs) are versatile platforms for developing various applications, owing to their structural diversity and functional tunability. The catalytic performance of metal-organic frameworks (MOFs) can be improved by introducing defects using monocarboxylate ligands, but the role of these ligands remains unclear. Herein, we show how doping MOFs with electron-withdrawing or electron-donating monocarboxylate ligands affects their oxygen evolution reaction (OER) performance. We further demonstrate that ferrocene derivatives as doped ligands can significantly enhance the OER performance of MOFs, owing to the strong synergistic effects between ferrocene derivatives and MOFs. Different from other doping MOF, ferrocene derivatives doped MOFs (1,1'-Fc-Ni-BDC) exhibit remarkable electrocatalytic activity with a low overpotential of 387 mV at 10 mA cm−2, and possess good electrochemical stability. Density functional theory (DFT) calculations reveal that the active sites are not on ferrocene derivatives, but rather on MOFs, and that ferrocene derivatives facilitate the formation of OER intermediates. Our findings provide new insights into the role of ligands in modulating the OER performance of MOFs. This work offers a new perspective to develop efficient MOF-based electrocatalysts by introducing electronegative metallocene ligands.