Structural reconstruction of cobalt and ferrocene-based metal-organic framework during 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 suggests 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 the current density of 10 mA cm–2. While this study demonstrates the necessity of investigating structural evolution of MOFs in electrocatalysis, it also shows potential of using MOFs as precursors in catalyst design.