ZIF‐8‐Derived N‐Doped Hierarchically Porous Carbon‐Supported Mn Nanoparticles Toward Oxygen Reduction for Zn–Air Batteries

The development of cost‐effective, high‐performance oxygen reduction reaction (ORR) electrocatalysts is pivotal for advancing energy conversion technologies such as metal–air batteries and fuel cells. Herein, we report a facile and efficient strategy to synthesize Mn nanoparticles loaded on N‐doped hierarchically porous carbon framework (Mn/N‐C) through utilizing ZIF‐8 as a carbon/nitrogen precursor and MnCl 2 ·4H 2 O as the Mn source. The synthesis integrates mechanical grinding with an NaCl‐assisted pyrolysis process, where molten NaCl acts as a dynamic template and intercalation agent to prevent structural collapse during carbonization, thereby creating a 3D porous architecture with coexisting micro‐, meso‐, and macropores. Physicochemical characterization reveals that the Mn/N‐C‐2 sample exhibits a high specific surface area (1770 m 2 /g), abundant defects, and uniform dispersion of Mn nanoparticles within the N‐doped carbon matrix. Electrochemical evaluations demonstrate that Mn/N‐C‐2 catalyst possesses a higher half‐wave potential ( E 1/2 ) of 0.836 V and a larger limiting current density ( J L ) of 5.54 mA/cm 2 , surpassing other control samples and most reported Mn‐based catalysts and comparable to that of commercial Pt/C. When integrated into Zn–air batteries (ZABs), Mn/N‐C‐2‐based ZABs deliver an open‐circuit voltage of 1.49 V and a peak power density of 150.51 mW/cm 2 , outperforming benchmark Pt/C‐based counterparts. This work offers a cost‐effective electrocatalyst for ORR and can be used instead of noble metals in ZABs.