ZIF-67 Derived Cu-Doped Electrocatalyst for Oxygen Reduction Reaction

In the present study, the catalytic activity of copper-loaded cobalt-based metal–organic framework (ZIF-67) composites was studied for their electrochemical oxygen reduction reaction (ORR). The Cu-ZIF-67 composite was prepared by the solvothermal method. After pyrolysis under argon atmosphere at 700 °C, the composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The electrochemical activity of the composites was tested for ORR in 0.1 M alkaline media using the three-electrode system by cyclic voltammetry (CV), Tafel plots, and electrochemical impedance spectroscopy (EIS). The composites showed variable activity with a current density of 1.32 mA cm⁻² at 0.71 V (versus reversible hydrogen electrode (RHE)) onset potential for 70 wt% Cu-ZIF-67, 7.5 mA cm⁻² at 0.82 V (versus RHE) onset potential for 50 wt% Cu-ZIF-67, and 11.85 mA cm⁻² at 0.85 V (versus RHE) for 30% Cu-ZIF-67. The increasing ratio of the ZIF-67 effect can be attributed to the increased activity of ZIF-67 with the synergistic effect of Cu toward increased current density.