A Facile and Template-Free One-Pot Synthesis of Mn₃O₄ Nanostructures as Electrochemical Supercapacitors

In this paper, we report an effective, simple, and cost-effective strategy of electrochemical deposition to prepare hausmannite Mn₃O₄ thin films for the applications of supercapacitors. Various precursor concentrations and deposition durations were manipulated to tailor the surface morphologies of Mn₃O₄ nanostructures and to optimize their electrochemical performances. The Mn₃O₄ samples prepared at 0.05 M Mn(NO₃)₂ solution for 30 min delivered a large gravimetric specific capacitance of 210 F g⁻¹ at a current density of 0.5 A g⁻¹, and a good rate capability over other samples. This superior electrochemical performance may be attributed to the improved electrode conductivity with increased accessible area for electrolytes ions. Furthermore, a nanocomposite film based on Mn₃O₄/carbon foam was fabricated by utilizing the developed optimized conditions. The Mn₃O₄/carbon foam films exhibit an excellent specific capacitance with negligible degradation in retaining specific capacitance values up to 4000 cycles. These findings could further broaden the applications of hausmannite Mn₃O₄ in electrochemical energy storage electrodes.