Fine Particles
Unusual Nanometer-Sized Nsutite from Mn(ClO4)2·6H2O-(C2H5)4NOH-CsMnO4–H2O Basic Systems
2003 年 36 巻 10 号 p. 1222-1226
詳細
2003 年 36 巻 10 号 p. 1222-1226
Nanometer-sized manganese oxides materials are one of the focuses for scientists in this field and novel properties may be found, due to quantum confinement effects. The most widely used cathode materials in primary alkaline batteries nsutite (γ-MnO2) is often described as an intergrowth of pyrolusite and ramsdellite tunnel structures. Our research concerns the preparation, structures, and properties of nanometer-sized nsutite with the longest diameter sizes of about 30–40 nm from Mn(ClO4)2·6H2O-(C2H5)4NOH-CsMnO4–H2O basic systems, instead of traditional nsutite synthesized in the acidic environments. Flat perfect crystal surfaces of nanometer-sized nsutite characterized by FESEM show that there are pure and fewer cation vacancies defects on the surface of the frameworks, further proved by IR, TG, and BET methods. The CV experiment results showed that the currents at –240 mV, corresponding to the homogeneous reduction from Mn4+ to Mn3+, were twice of traditional samples from acidic environments, due to the small particle size, fewer cation vacancies, and larger numbers of Mn4+ ions on the surfaces.
