Polyaniline (Pani) and polypyrrole (Ppy) half hollow spheres with different shell thicknesses were successfully synthesized by three steps process using polystyrene (PS) as the core. The PS core was synthesized by emulsion polymerization. Aniline and pyrrole monomers were polymerized on the surface of the PS core. The shells of Pani and Ppy were fabricated by adding different amounts of aniline and pyrrole monomers. PS cores were dissolved and removed from the core shell structure by solvent extraction. The thicknesses of the Pani and Ppy half hollow spheres were observed by FE-SEM and FE-TEM. The chemical structures of the Pani and Ppy half hollow spheres were characterized by FT-IR spectroscopy and UV-Vis spectroscopy. The shell thicknesses of the Pani half hollow spheres were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, while the shell thicknesses of the Ppy half hollow spheres were 16.0, 22.0, 27.0, and 34.0 nm. The shell thicknesses of Pani and Ppy half hollow spheres linearly increased as the amount of the monomer increased. Therefore, the shell thickness of the Pani and Ppy half hollow spheres can be controlled in these ranges.
Silica-manganese oxides with a core-shell structure were synthesized via precipitation of manganese oxides on the SiO 2 core while varying the concentration of a precipitation agent. Elemental analysis, crystalline property investigation, and morphology observations using low-and high-resolution electron microscopes were applied to the synthesized silica-manganese oxides with the core-shell structure. As the concentration of the precipitating agent increased, the manganese oxide shells around the SiO 2 core sequentially appeared as Mn 3 O 4 particles, Mn 2 O 3 +Mn 3 O 4 thin layers, and α-MnO 2 urchin-like phases. The prepared samples were assembled as electrodes in a supercapacitor with 0.1 M Na 2 SO 4 electrolyte, and their electrochemical properties were examined using cyclic voltammetry and charge-discharge cycling. The maximum specific capacitance obtained was 197 F g −1 for the SiO 2 -MnO 2 electrode due to the higher electronic conductivity of the MnO 2 shell compared to those of the Mn 2 O 3 and Mn 3 O 4 phases.
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