A new Mn x O y /carbon nanorods derived from bimetallic Zn/Mn metal–organic framework as an efficient oxygen reduction reaction electrocatalyst for alkaline Zn-Air batteries

In this work, nanorods like bimetallic Zn/Mn metal–organic-frameworks (MOFs) are proposed as the precursor for preparing Mn x O y /porous carbon composite as a high-performance catalyst. The synthesis conditions, including the ratio of Zn:Mn and reaction time, are systematically investigated. The optimized sample has nanorods like morphology with a length of 200 nm and a diameter of 50 nm. Electrochemical tests show that the initial potential of the optimized Mn x O y /porous carbon composite is 0.896 V( vs. reversible hydrogen electrode, RHE), the half-wave potential is 0.763 V ( vs. RHE), and the kinetic current is 0.962 mA cm −2 (0.8 V). It has higher stability and selectivity than commercial Pt/C. The results reveal that the existence of Zn grain refinement occurs in Mn x O y /carbon nanomaterials and increases its pore structure. The obtained material possesses a large electrochemical active area, indicating the higher exposed active sites and enhanced catalytic performance. Besides, the assembled Zn-air battery with Mn x O y /porous carbon composite as cathode catalyst exhibits a power density of 0.14 W cm −2 , close to that of commercial Pt/C. This work provides adequate data for further study of bimetallic MOF-derived materials as high-performance ORR catalysts.