A simple one step approach to preparation of γ-MnOOH multipods and β-MnO2 nanorods
ABSTRACT Multipod-like γ-MnOOH and rod-like β-MnO2 nanocrystals are synthesized by oxidization of manganese sulphate hydrate (MnSO4·H2O) using sodium chlorate (NaClO3) as an oxidizing agent in a simple hydrothermal reaction system in the absence of any templates, catalysts, or organic reagents. The powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to characterize the as-prepared products. Based on the results of XRD and SEM, multipod-like γ-MnOOH can be transformed into rod-like β-MnO2 nanocrystals via one step synthetic route by simply increasing the reaction time while other conditions are kept constant. And a possible transfer mechanism via a nucleation–dissolution–anisotropic growth–recrystallization process is presented.
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ABSTRACT: Ag-doped MnO2 pseudocapacitor electrodes with dendrite and foam-like structures were successfully produced for the first time using an electrodeposition method employing structure-directing agents, i.e., sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) acting through micelle formation at solid-liquid interfaces. Doping silver with MnO2 enhanced their electronic conductance. Controlling pseudocapacitor electrode morphologies with surfactants accelerated ion transport. The specific capacitance values of the Ag-doped MnO2 films produced with SDS and CTAB, measured in 0.5 M Na2SO4 at a scan rate of 5 mV s(-1) were 551 and 557 F g(-1), respectively. These values are about 2.7-fold higher than that of the pure MnO2 film and about 1.4-fold higher than that of the Ag-doped MnO2 film made without using surfactants.Journal of Solid State Electrochemistry 01/2012; 16(8):2623-2629. · 2.28 Impact Factor