The biggest challenge is to develop a low cost and readily available catalyst to replace expensive commercial Pt/C for efficient electrochemical oxygen reduction reaction (ORR). In this research, closo-[B₁₂H₁₂]²⁻ and 1,10-phenanthroline-iron complexes were introduced into the porous metal-organic framework by impregnation method, and further annealing treatment achieved the successful anchoring of single-atom-Fe in B-doped CN Matrix (FeN4CB). The ORR activity of FeN4CB is comparable to the widely used commercial 20 wt% Pt/C. Where the half-wave potential (E_1/2) in alkaline medium up to 0.84 V, and even in the face of challenging ORR in acidic medium, the E_1/2 of ORR driven by FeN4CB is still as high as 0.81 V. When FeN4CB was used as air cathode, the open circuit voltage of Zn-air battery reaches 1.435 V, and the power density and specific capacity are as high as 177 mW cm⁻² and 800 mAh g_Zn⁻¹ (theoretical value: 820 mAh g_Zn⁻¹), respectively. The dazzling point of FeN4CB also appears in the high ORR stability, whether in alkaline or acidic media, E_1/2 and limiting current density are still close to the initial value after 5000 times cycles. After continuously running the charge-discharge test for 220 h, the charge voltage and discharge voltage of the rechargeable zinc-air battery with FeN4CB as the air cathode maintained the initial state. Density functional theory calculations reveals that introducing B atom to Fe–N4–C can adjust the electronic structure to easily break O = O bond and significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.

最大的挑战是开发一种低成本且易于获得的催化剂，以替代昂贵的商业 Pt/C，以实现高效的电化学氧还原反应 (ORR)。本研究通过浸渍法将接近-[B ₁₂ H ₁₂ ] ^2-和1,10-菲咯啉-铁配合物引入多孔金属-有机骨架中，进一步退火处理实现了单原子-Fe的成功锚定在 B 掺杂的 CN 基体 (FeN4CB) 中。FeN4CB 的 ORR 活性与广泛使用的商业 20 wt% Pt/C 相当。其中碱性介质中的半波电位 ( E _1/2 ) 高达 0.84 V，即使面对酸性介质中具有挑战性的 ORR，E _1/2FeN4CB驱动的ORR仍然高达0.81 V。当FeN4CB作为空气阴极时，锌空气电池的开路电压达到1.435 V，功率密度和比容量高达177 mW cm ^-2和800 mAh g _Zn ^-1（理论值：820 mAh g _Zn ^-1）。FeN4CB的耀眼之处还表现在高ORR稳定性，无论是在碱性还是酸性介质中，E _1/25000次循环后极限电流密度仍接近初始值。连续进行220 h的充放电试验后，以FeN4CB为空气阴极的锌空气充电电池的充放电电压保持初始状态。密度泛函理论计算表明，将 B 原子引入 Fe-N4-C 可以调整电子结构，从而轻松破坏 O = O 键并显着降低定速步骤的能垒，从而提高 ORR 活性。