For Abstract see ChemInform Abstract in Full Text.

Nanosized γ-MnOOH (manganite) has been synthesized by a new route via the reduction of KMnO4 with sucrose and MnSO4 in acidic medium under refluxing conditions for 4 and 6 h. Characterization of these manganite materials using XRD, FESEM, TEM, TGA, and IR were carried out. The obtained manganite samples using the new route were compared against a conventionally prepared one where synthesis involved the oxidation of MnSO4 with a H2O2 solution in a basic medium. Two new synthetic methods were developed, one involving addition of KMnO4 into a solution of both sucrose and MnSO4 while the other involved addition of KMnO4 solution into sucrose only followed by addition of MnSO4 (s). The latter method yielded smaller particles (up to 30 nm) than the former method (up to 80 nm) and the conventionally prepared manganite (up to 50 nm). The synthesized manganite materials exhibited promising characteristics when tested as electrocatalysts in the reduction of O2. The larger particles gave higher peak currents in CV. When incorporated in Yardney's medium-sized lithium-air battery, the larger particles gave higher specific capacity (up to 2.2 A·h/g), which corresponds to about a 38% increase in specific energy of the battery when compared to a battery where no manganite was incorporated.

Cryptomelane-type K-OMS-2 nanomaterials with high surface area are synthesized from a mixture of KMnO4 and Mn(OAc)2·4H2O powders at low temperature in a very short time (80°C, 1 h). The samples are characterized by XRD, SEM, and TEM. The materials exhibit nanorod morphologies with average diameters of about 10 nm and lengths of about 50 nm. They show improved catalytic activity for the oxidation of alcohols compared with the conventional K-OMS-2 materials. The fast, inexpensive, and environmentally friendly solvent-free synthesis method has the potential of being used in scaled-up syntheses of K-OMS-2 and other transition-metal-ion-substituted manganese oxide nanomaterials. -(DING, Y.-S.; SHEN, X.-F.; SITHAMBARAM, S.; GOMEZ, S.; KUMAR, R.; CRISOSTOMO, V. M. B.; SUIB*, S. L.; AINDOW, M.; Chem. Mater. 17 (2005) 21, 5382-5389; Dep. Chem., Univ. Conn., Storrs, CT 06269, USA; Eng.) -W. Pewestorf 01-014

A continuous flow microwave method has been developed for the synthesis of cryptomelane-type K-OMS-2 nanomaterials in a mixed aqueous−organic solvent system. The system is ideal for multikilogram synthesis of K-OMS-2 nanomaterials. The synthesized nanomaterials have crystallite sizes of about 1.8 nm with a surface area of 213 m2/g. X-ray diffraction (XRD), electron microscopy (SEM and TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), nitrogen sorption experiments, and potentiometric titrations have been used to characterize the nanomaterials. Kinetically, an increase in power has a direct relation to increase in temperature, and this has an effect on reaction rate. The synthesized materials show excellent results in the oxidation of 2,3,6-trimethylphenol.

A fast and single-step method was successfully developed toward synthesizing well-ordered organic-inorganic hybrid layered manganese oxide (LMO) nanocomposites and Keggin/organic ions intercalated into layered manganese oxide at room temperature in 1 day. The ordering of layered structures is highly dependent on pH and drying conditions. The Keggin/organic intercalated LMO shows improved thermal stability of the layered structure over that of hybrid LMO.