Co-based Bifunctional Electrocatalyst with Sturdy Three-Dimensional Frame Construction for Oxygen Reduction and Oxygen Evolution Reactions

Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles. The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived Co-N-C materials, which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions. The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80% after 25,000 s of continuous operation. It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.