Sustainable metal-air batteries demand high-efficiency, environmentally-friendly, and non-precious metal-based electrocatalysts with bifunctionality for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this research, novel functional carbon nanotubes with multi-active sites including well-dispersed single-atom iron throughout the walls and encapsulated ultrafine iron nanoparticles were synthesized as an electrocatalyst (Fe_NP@Fe-N-C) through one-step pyrolysis of metal-organic frameworks. High-resolution synchrotron powder X-ray diffraction and X-ray absorption spectroscopy were applied to characterize the unique structure of the electrocatalyst. In comparison to the commercial Pt/C and RuO₂ electrodes, the newly prepared Fe_NP@Fe-N-C presented a superb bifunctional performance with its narrow potential difference (E_gap) of 0.73 V, which is ascribed to the metallic Fe nanoparticles that boosts the adsorption and activation of oxygen on the active sites with an enhanced O₂ adsorption capacity of 7.88 cm³ g⁻¹ and synergistically functionalizes the iron atoms dispersed on the nanotubes. A rechargeable zinc-air battery based on Fe_NP@Fe-N-C exhibited a superior open-circuit voltage (1.45 V), power density (106.5 mW cm⁻²), and stable cycling performance. The green technique developed in this work for the fabrication of functional nanotubes raises the prospect of making more efficient electrocatalysts for sustainable energy cells.

可持续的金属空气电池需要高效、环保、非贵金属基电催化剂，其具有氧还原反应 (ORR) 和析氧反应 (OER) 的双功能。在这项研究中，通过一步热解金属，合成了具有多活性位点的新型功能性碳纳米管，包括在整个壁上分散良好的单原子铁和封装的超细铁纳米粒子作为电催化剂（Fe _NP @Fe-NC）。有机框架。应用高分辨率同步加速器粉末 X 射线衍射和 X 射线吸收光谱来表征电催化剂的独特结构。与商用 Pt/C 和 RuO ₂电极相比，新制备的 Fe _NP@Fe-NC 呈现出极好的双功能性能，其电势差（E_间隙）为 0.73 V，这归因于金属 Fe 纳米颗粒促进了活性位点上氧的吸附和活化，并增强了 O ₂吸附能力7.88 cm ³ g ^-1并协同功能化分散在纳米管上的铁原子。基于 Fe _NP @Fe-NC的可充电锌空气电池表现出优异的开路电压 (1.45 V)、功率密度 (106.5 mW cm ^-2)，以及稳定的循环性能。这项工作中开发的用于制造功能性纳米管的绿色技术为为可持续能源电池制造更高效的电催化剂提供了前景。