Manganese oxide(III)/carbon hybrids with interesting morphologies as improved active materials for supercapacitors

Mn2O3/C hybrids with almond-like, peach-like and peanut-like morphologies are fabricated via hydrothermal method followed by annealing in air at ambient pressure. Their physical properties and morphologies are characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), Brunauer-Emrnett-Teller (BET), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Almond-like Mn2O3/C (Mn2O3/C-ALL) and peach-like Mn2O3/C (Mn2O3/C-PCL) hybrids are highly porous with large-sized mesopores. In contrast, peanut-like Mn2O3/C (Mn2O3/C-PNL) is composed of densely packed slender nanofibers. The results show Mn2O3 and carbon have homogeneous contact accounting for high conductivity. In 1.0 M Na2SO4 aqueous electrolyte, Mn2O3/C-PCL has the highest specific capacitance of 158.8 F g(-1) at 1.0 A g(-1), compared to Mn2O3/C-ALL (105.1 F g(-1)) and Mn2O3/C-PNL (77.5 F g(-1)). Furthermore, the capacitance retention of Mn2O3/C-PCL achieves 48.8% upon a 50-fold increase in current density. Finally, the Mn2O3/C-PCL displays an impressive long-term cycle stability of 90.6% specific capacitance retention after 10,000 cycles at 1.0 A g(-1). Therefore, this work highlights the importance of morphology in Mn2O3/C hybrids design to obtain high performance supercapacitor materials. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.