Structural Reconstruction of a Cobalt- and Ferrocene-Based Metal−Organic Framework during the Electrochemical Oxygen Evolution Reaction

Metal-organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for oxygen evolution reaction (OER) due to their unique modular structures that present a hybrid between molecular and heterogeneous catalysts, featuring well-defined active sites. However, many fundamental questions remain open regarding the electrochemical stability of MOFs, structural reconstruction of coordination sites, and the role of in situ-formed species. Here we report structural transformation of a surface-grown MOF containing cobalt nodes and 1,1’-ferrocenedicarboxylic acid linkers (denoted as CoFc-MOF) during OER in alkaline electrolyte. Ex situ and in situ investigations of CoFc-MOF film suggest that the MOF acts as a pre-catalyst and undergoes a two-step restructuring process under operating conditions to generate a metal oxyhydroxide phase. The MOF-derived metal oxyhydroxide catalyst, supported on nickel foam electrodes, displays high activity towards OER with an overpotential of 190 mV at a current density of 10 mA cm^–2. While this study demonstrates the necessity of investigating structural evolution of MOFs in electrocatalysis, it also shows the potential of using MOFs as precursors in catalyst design.