Solvothermal synthesis of Mn₃O₄ nanoparticle/graphene sheet composites and their supercapacitive properties

Mn₃O₄ nanoparticle/graphene sheet (GM) composites were synthesized via a one-pot and low-cost solvothermal process in an ethanol solution. The as-prepared materials were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Results showed that the nanosized Mn₃O₄ particles had tetragonal hausmannite structure and were successfully loaded on the graphene sheets. Moreover, the electrochemical performances of GM composites produced by different mass percents of Mn²⁺/graphite oxide (GO) were evaluated by means of cyclic voltammetry and galvanostatic charge-discharge studies. The composite prepared with Mn²⁺/GO mass percent of 10: 90 showed a high specific capacitance of 245 F/g at 5 mV/s in the 6 M KOH solution and better long-term stability along with 81% of its initial capacitance after 1200 cycles at 0.5 A/g.