Hydrothermal etching preparation and growth process of γ- MnOOH with novel hexagram morphology

Well-defined single crystal gamma-MnOOH with novel hexagram morphology was prepared by hydrothermal treating a suspension of ethyl acetate and KMnO4 at 200 degrees C for 48 h, and its formation process had been investigated on the basis of XRD, FESEM, TEM, HRTEM, and SAED analyses. In keeping hydrothermal treatment temperature and reaction time, ethyl acetate played an important role in controlling the crystal phase and morphology of the obtained materials, which was used as both reducing agent and etchant. It hydrolyzed into acetic acid and ethanol slowly and caused an acidic reaction environment accompanied with hydrothermal reaction. The acetic acid was adsorbed on the lateral of gamma-MnOOH with multiple branched nanorods, which caused a soft etching process and the lateral of the multiple branched nanorods became sharper and thinner and finally transformed into gamma-MnOOH with hexagram morphology. The prepared gamma-MnOOH with novel hexagram morphology is expected to be used for a fundamental study in surface science and for potential applications such as adsorbent, electro-catalyst, sensing and so on. (C) 2015 Elsevier Masson SAS. All rights reserved.