Facile synthesis of nickel doped walnut-like MnO2 nanoflowers and their application in supercapacitor

The hierarchical walnut-like nickel-doped MnO2 nanostructure was successfully synthesized via a simple hydrothermal method without using any template or surfactant. The samples are characterized by XRD, EDS, SEM, and TEM for its composition, structure/morphology. The results show that the novel walnut-like MnO2 nanoflowers are composed of many interleaving thin nanosheets. Meanwhile, the samples present ideal electrochemical behavior, such as high specific capacitance (153.6 F g−1 at 1 A g−1) and outstanding cycling stability (the capacitance even shows a retention of 103 % after 1000 cycles). These remarkable and excellent results prove the walnut-like MnO2 nanomaterial has a great potential of application in the future energy storage device.