Ferrocene unit substitution in nickel(<scp>ii</scp>) porphyrin(2.1.2.1) induces an extremely low oxygen evolution reaction overpotential

This study reports the synthesis, characterization, structure and the oxygen evolution reaction (OER) performance of ferrocene-substituted nickel(II) porphyrin(2.1.2.1) complexes. The Ni-3 complex, functionalized with two ferrocene units, demonstrates exceptional OER activity, achieving an overpotential of 280 mV at 10 mA cm^-2 in alkaline media. This enhancement is ascribed to the electron-rich ferrocene moieties, which act as efficient electron-transfer mediators during catalysis. DFT calculations corroborate these findings, revealing a theoretical overpotential of 0.79 eV for the dual-ferrocene-substituted catalyst. These results underscore the critical role of ferrocene in lowering the overpotential of molecular OER catalysts.