Mesoporous Polymer for Metal Ion Adsorption and Its Calcined Product for Oxygen Reduction Reaction

The development of efficient functional materials for environmental and energy applications remains a significant challenge. Herein, we report a novel emulsion‐assisted oxidative polymerization strategy for synthesizing mesoporous poly(diaminonaphthalene) (PDAN) with uniform morphology and well‐defined mesopores. This method overcomes the rapid and uncontrolled polymerization kinetics associated with conventional oxidative routes, enabling the formation of small spherical nanoparticles with ordered mesopores. The resulting PDAN exhibits exceptional metal ion adsorption performance, particularly for Fe ³⁺ , demonstrating both high capacity and rapid kinetics that significantly surpass those of many previously reported polymer adsorbents. Moreover, the adsorbed Fe ³⁺ serves as a precursor for preparing nitrogen‐doped mesoporous carbon embedded with Fe ₃ C nanoparticles (NCs‐Fe) through direct pyrolysis. The form of the iron species is the critical determinant of its oxygen reduction reaction (ORR) performance. The optimized NCs‐Fe catalyst demonstrates outstanding ORR activity, featuring a half‐wave potential of 0.88 V versus RHE, surpassing commercial 20 wt% Pt/C. When applied in zinc–air batteries, it delivers a high power density of 120 mW cm ⁻² and excellent cycling stability. This work presents a closed‐loop material design that integrates efficient metal ion capture with the fabrication of high‐performance ORR electrocatalysts.