Facile Synthesis of Thiophene-Based MOF-Derived Bimetallic ZnM Sulfides (M═Fe, Co, Ni) for Electrocatalytic Oxygen Reduction and Zinc Air Batteries

Transition metal sulfides (TMSs) have emerged as promising catalysts for the oxygen reduction reaction (ORR), yet achieving activity comparable to Pt-based benchmarks remains challenging. Herein, we present an in situ MOF-carbonization strategy to prepare transition metal-doped ZnS nanoparticles embedded in N, S-codoped carbon nanorods (M─ZnS/NSCNR, M═Fe, Co, Ni). Structural characterization confirms successful dopant integration into ZnS lattices within hierarchical carbon substrates, yielding enhanced defect density and optimal porosity. Furthermore, electrochemical evaluation reveals Fe─ZnS/NSCNR's exceptional ORR performance in 0.1 M KOH, exhibiting a half-wave potential of 0.897 V and limiting current density of 5.20 mA cm −2— surpassing both Pt/C and Co/Ni analogues. In zinc-air batteries, it can achieve a peak power density of 132.1 mW cm −2 , specific capacity of 685.6 mAh g Zn −1 , and minimal voltage gap (0.96 V) during 70 h cycling. DFT calculations show that transition metal doping effectively modulates the ZnS electronic structure by adjusting the position of the d-band center (d ε ). The Fe-doped ZnS model exhibits a well-balanced d ε value (−1.34 eV) and reduced OOH * adsorption barrier (0.62 eV), leading to enhanced ORR activity. This work establishes a scalable route for designing noble metal-free, MOF-derived ORR catalysts with superior activity-durability characteristics for advanced energy technologies.