"Wiring" Fe-N_x -Embedded Porous Carbon Framework onto 1D Nanotubes for Efficient Oxygen Reduction Reaction in Alkaline and Acidic Media

This study presents a novel metal-organic-framework-engaged synthesis route based on porous tellurium nanotubes as a sacrificial template for hierarchically porous 1D carbon nanotubes. Furthermore, an ultrathin Fe-ion-containing polydopamine layer has been introduced to generate highly effective FeN_x C active sites into the carbon framework and to induce a high degree of graphitization. The synergistic effects between the hierarchically porous 1D carbon structure and the embedded FeN_x C active sites in the carbon framework manifest in superior catalytic activity toward oxygen reduction reaction (ORR) compared to Pt/C catalyst in both alkaline and acidic media. A rechargeable zinc-air battery assembled in a decoupled configuration with the nonprecious pCNT@Fe@GL/CNF ORR electrode and Ni-Fe LDH/NiF oxygen evolution reaction (OER) electrode exhibits charge-discharge overpotentials similar to the counterparts of Pt/C ORR electrode and IrO₂ OER electrode.