▎ 摘　　要

The development of active, inexpensive, and durable nonprecious-metal electrocatalysts to replace high-cost Pt-based catalysts towards the commercialization of fuel cell technology is the focus in recent years. In this regard, we report a facile one-pot hydrothermal synthesis of self-assembled manganese sulfide on graphene layers (MnS/G), and is recognized as a nonprecious-metal catalyst for the efficient oxygen reduction reaction (ORR) in an alkaline medium. The phase purity and surface morphologies are investigated by using X-ray diffraction and scanning electron microscopic techniques, respectively. Optimized MnS/G with 50% Mn exhibited excellent ORR properties with onset and half-wave potentials of 0.83 and 0.71 V vs.RHE, respectively. While evaluating the durability, only a 90 mV negative shift in its half-wave potential is observed after 5000 repeated potential cycles, which is also ascertained for up to 48 h of operation at a constant potential by using a chronoamperometric technique with 28% degradation in the current. The optimized material is utilized as a cathode catalyst in fabricating membrane electrode assembly for performance evaluation in an anion exchange membrane fuel cell. A peak power density of 12 mW cm(-2) is realized in H-2-O-2 feeds under ambient temperature and pressure; thus, it looks as an alternative non-preciousmetal catalyst for fuel cell applications.