Hierarchical porous Fe/N/S-doped carbon with a high content of graphitic nitrogen (FeNS/HPC) has been successfully synthesized by a facile dual-template method. FeNS/HPC shows not only macropores resulting from the dissolution of the SiO template, but abundant mesopores were also obtained after removing the in situ generated FeO nanoparticles on the ultrathin (∼4 nm) carbon shell of the macropores. Moreover, micropores are produced during the thermal pyrolysis of the carbon precursors. With respect to the electrochemical performance in the oxygen reduction reaction (ORR), FeNS/HPC not only exceeds other prepared porous carbon materials completely but also shows higher onset potential (0.97 vs 0.93 V), half-wave potentials (0.87 vs 0.83 V), and diffusion current density (5.5 vs 5.3 mA cm) than those of Pt/C. Furthermore, FeNS/HPC also exhibits outstanding stability and methanol tolerance, making it a competent candidate for ORR. The following aspects contribute to its excellent ORR performance. (1) High content of graphitic N (5.1%) and codoping of pyridinic N species, thiophene-S, FeN, and graphitic carbon-encapsulated iron nanoparticles, providing highly active sites. (2) The hierarchical porous mesh structure with micro-, meso-, and macroporosity, accelerating the mass transfer and facilitating full utilization of the active sites. (3) The high specific surface area (1148 m g) of the graphitic carbon shell, assuring a large interface and rapid electron conduction for ORR.

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The pedestal of the rechargeable zinc–air battery (ZAB) is based on high‐performance bifunctional oxygen reduction/evolution reactions (ORR/OER) electrocatalysts. Herein, without any template or surfactant, in situ grown nitrogen‐doped carbon‐nanotube (NCNT)‐embedded with two phases of bimetal CoFe alloys and CoFe2O4 spinel oxide are constructed, using inexpensive materials of glucose, urea, and cobalt/iron acetates by programing the pyrolysis temperature. The obtained catalyst with optimal cobalt/iron acetates mass ratio (1:1) denoted as CoFe–CoFe2O4–NCNT not only exceeds Pt–Ru/C in terms of ORR half‐wave potentials [(0.88 vs 0.84 V versus reversible hydrogen electrode (RHE)] and limiting current densities (6.40 vs 5.40 mA cm−2), but also manifests superior OER activity with the potentials of (1.58 vs 1.67 V versus RHE) at 10 mA cm−2. Therefore, CoFe–CoFe2O4–NCNT exhibits a smaller ΔE value of (0.70 V versus RHE), surpassing that of Pt–Ru/C (0.85 V versus RHE) and shows excellent stability as well as outstanding methanol tolerance compared with the Pt–Ru/C commercial catalyst. In addition, CoFe–CoFe2O4–NCNT applied as a bifunctional air electrode in rechargeable ZAB displays a promising rechargeability performance with high‐discharge and low‐charge potentials and a relatively stable potential gap under 550 cycles, outperforming those of Pt–Ru/C.

Highly efficient and low‐cost bifunctional electrocatalysts for oxygen reduction and evolution reactions (ORR/OER) are central to new generation rechargeable metal–air batteries. Herein, hierarchical microspheres assembled by in situ generated Co4N nanoparticles (Co4N Nps)‐embedded nitrogen‐doped carbon nanotubes (Co4N@NCNTs) are constructed by a facile urea acid (UA)‐assisted pyrolysis of zeolitic imidazole framework (ZIF)‐67. In this strategy, the UA sharply decomposes at 440 °C to carbonaceous gases, which facilitate the nucleation of Co4N Nps for the catalytic growth of the NCNT microspheres structure from the intermediate ZIF‐67 polyhedrons. The as‐prepared Co4N@NCNTs exhibit high N content, abundant Co4N active species, high electron conductivity, and large specific area on a hierarchical micro‐mesoporous structure. Therefore, the Co4N@NCNTs not only exceed Pt/C in terms of ORR half wave potential (0.85 vs 0.83 V) and limiting current density (5.50 vs 5.20 mA cm−2), but also manifest comparable OER activity with Ru/C. In the rechargeable zinc–air battery test, the bifunctional Co4N@NCNTs show excellent performance with high discharge and low charge potentials and relatively stable voltage gap as long as 500 cycles, which greatly outperform those of commercial Pt–Ru/C.