Partial etching of ZIF-67 nanosheets for the fabrication of S-FeOx/ZIF-67/NF electrodes enabling highly efficient oxygen evolution reaction at large current densities

Highly efficient and economical oxygen evolution reaction (OER) electrocatalysts are instrumental in the utilization and storage of renewable sources. Here, we introduce a straightforward method for the in situ growth of sulfur-doped iron oxide (S-FeO x ) and two-dimensional (2D) zeolitic imidazole framework-67 (ZIF-67) nanoarrays on three-dimensional (3D) nickel foam (NF), yielding a 3D S-FeO x /ZIF-67/NF electrocatalyst. The distinctive sheet-like structure and porous framework of S-FeO x /ZIF-67/NF significantly increase the electrochemical active surface area. The prepared S-FeO x /ZIF-67/NF exhibits outstanding electrocatalytic OER activity, achieving a remarkably low overpotential of 236 mV at a current density of 100 mA/cm 2 . Furthermore, S-FeO x /ZIF-67/NF demonstrates the capability to deliver industrial-level large current densities, requiring overpotentials of merely 291 and 334 mV to attain current densities of 500 and 1000 mA/cm 2 , respectively. Moreover, it maintains stable operation for over 80 h at a current density of 1000 mA/cm 2 , with the sheet-like structure remaining intact and no significant activity decay observed. This investigation offers a strategic approach for the systematic development and fabrication of OER electrocatalysts suitable for large current conditions.