Research on ORR and OER performance of Co based catalyst from ZIF-67

Effective bifunctional electrocatalysts for Oxygen reduction reaction and Oxygen evolution reaction (ORR and OER) are key for fuel cells and water electrolysis. Co-based dodecahedral bifunctional catalysts, rich in Co-N, pyridinic nitrogen, and metallic cobalt nanoparticles, were synthesized by pyrolysis of ZIF-67. The obtained ZIF-67–6 catalyst showed an onset potential of 0.90 V, a half-wave potential of 0.83 V (vs. RHE), a limiting diffusion current density of 5.24 mA cm⁻² for ORR, and an overpotential of 1.50 V (vs. RHE) at 10 mA cm⁻² for OER. These values are comparable to those of commercial 20 % Pt/C (0.89 V onset potential, 0.83 V half-wave potential, and 4.27 mA cm⁻² limiting diffusion current density) and IrO₂ (1.53 V overpotential at 10 mA cm⁻²). The catalyst maintained 92.11 % of its current density after polarizing at 0.80 V for 10,000 s. ZIF-67–6′s high performance and stability are attributed to the porous structure from MOF pyrolysis, the deposited cobalt nanoparticle, and the higher Co-N and the pyridinic nitrogen content. This work offers a practical method to produce nitrogen- and cobalt-rich bifunctional electrocatalysts with dodecahedral structures.