Mn3O4 nanoparticles anchored to multiwall carbon nanotubes: a distinctive synergism for high-performance supercapacitors

Abstract

Modified hydrothermal route (MHT)-evolved Mn₃O₄ nanoparticles of ∼60 nm diameter were anchored onto a conductive multiwalled carbon nanotubes (MWCNTs) backbone (again under MHT) to produce an energy storage composite. To obtain the benefits of a low cost and stable MWCNT/Mn₃O₄ composite as a supercapacitor, cyclic voltammetry (CV) and galvanostatic charge–discharge measurements (GCD), as well as cycling stability and electrochemical impedance studies (EIS) have been performed. The electrochemical measurements reveal the suitability of the as-synthesized MWCNT/Mn₃O₄ composite as an electrode material with a highest specific capacitance of 441 F g⁻¹ at 2 mV s⁻¹ scan rate, which is 1.4 times higher than the specific capacitance (312 F g⁻¹ at a scan rate of 2 mV s⁻¹) of the bare Mn₃O₄ nanoparticle. MWCNT/Mn₃O₄ shows an excellent rate capability, outstanding long-term cyclic stability (98% capacity retention after 1000 consecutive cycles) and better power density and energy density. Due to the synergistic effect operating between the pseudocapacitor Mn₃O₄ nanoparticle and the conductive MWCNT, the capacitive performance of the composite electrode was considerably improved, and we perceive that the composite effect could have benefit in terms of supercapacitor application. These interesting improved material properties of the as-synthesized material indicate that the material is a suitable candidate for use in future energy storage applications.