Iron-Containing Porphyrins Self-Assembled on ZnO Nanoparticles as Electrocatalytic Materials for Oxygen Reduction

Nonprecious metal electrocatalysts (NPMEs) have been recognized as highly promising oxygen electroreduction catalysts, but improving their activity and stability in acidic electrolyte remains critical. Here, we integrated self-assembly technology induced by rotary evaporation with the hard-template method to synthesize Fe–N-codoped NPMEs with large specific surface areas and hierarchical pore structure. The presence of Fe3+ assisted complete removal of the ZnO hard template at a relatively low temperature, which is beneficial for both the in situ growth of micropores/mesopores within the carbon layers and the retention of more nitrogen-containing groups. The obtained Fe–N–C/ZnO porous carbon material exhibited outstanding oxygen reduction reaction catalytic activity, along with respectable electrochemical stability in a perchloric acid electrolyte. Applied in fuel cells, the electrocatalyst loading was reduced to 2.0 mg/cm2 because of increased mass transfer arising from the hierarchical porous structure and resulting in a power density of 700 mW/cm2.