Scalable Synthesis of Fe/N-Doped Porous Carbon Nanotube Frameworks for Aqueous Zn-Air Batteries.

Aqueous Zn-air batteries are emerging to be ideal next-generation energy-storage devices with high safety and high energy/power densities. However, the rational design and fabrication of low-cost, highly efficient, and durable electrocatalysts on the cathode side remain highly desired. Herein, template-assisted, scalable Fe-implanted N-doped porous carbon nanotube networks (Fe-N-CNNs) have been synthesized based on an environmentally friendly template hydroxyapatite nanowires (HAP NWs). Thanks to the hierarchical meso/micropores, high specific surface area, and abundant active sites, the optimized Fe-N-CNNs exhibit excellent oxygen reduction activity. Furthermore, the Zn-air batteries based on the Fe-N-CNNs cathode deliver a high discharge voltage of 1.27 V at a current density of 20 mA cm-2 and a large peak power density of 202.2 mW cm-2 . More far-reaching, this HAP-based template strategy opens a new avenue toward the mass production of efficient, cost-effective electrocatalysts, and the Fe-N-CNNs with hollow interiors are expected to extend their other potential uses in energy storage, molecular sieves, adsorbents, and biomedical engineering.