Single-crystal growth of MnOOH and beta-MnO2 microrods at lower temperatures

摘要

Single-crystal MnOOH microrods were prepared hydrothermally by reducing KMnO4 with NH4Cl at 150 degrees C for 24 h. After the subsequent heat treatment of the as-prepared MnOOH microrods at 350 degrees C for 10 h in air, single-crystal beta-MnO, inicrorods were obtained. which retained the similar morphologies of MnOOH inicrorods. The products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron inicroscopy (TEM). The influences of different reductants, the molar ratio between reaction materials, and temperature on the morphology and phase of the final products tinder hydrothermal conditions are discussed. The reaction temperature and reductant NH4Cl were crucial factors for the formation and morphologies of MnOOH microrods. Based on the experimental results and MnOOH crystal structure. a possible formation mechanism has been proposed on the growth of MnOOH inicrorods. (c) 2005 Elsevier Ltd. All rights reserved.