Hydrothermal Synthesis of MnO<sub>2</sub> Microspheres and Their Degradation of Toluene
Meijuan Lu, Yulian Ma, Danping Li, Min Jiang, Chenglong Yu
Abstract
High Resolution Image Download MS PowerPoint Slide Various urchin-like MnO 2 materials were obtained with a facile hydrothermal method through controlling the Mn precursor, reaction time, and reaction temperature. The property of MnO 2 materials was characterized by scanning electron microscopy, X-ray diffraction, and H 2 temperature-programmed reduction. The results showed that the Mn precursor could significantly impact the morphology of as-prepared MnO 2 . When the precursor was Mn(CH 3 COO) 2 ·4H 2 O, the MnO 2 morphology consisted of tennis-like microspheres assembled by nanorods. While the precursor was MnCl 2 ·4H 2 O, the sample morphology was a chestnut shell, and the samples were sea urchin microspheres, as the precursor was MnSO 4 ·H 2 O. At the same time, the morphology of MnO 2 was affected by hydrothermal time and temperature. The nanoneedles on the microsphere surface gradually lengthened with increasing hydrothermal time and hydrothermal temperature, until nanowires were formed. MnO 2 crystallinity was also influenced by hydrothermal temperature. It was γ-MnO 2 as the temperature was 50 and 80 °C while evolved to be α-MnO 2 and β-MnO 2 when the temperature increased to 140 °C. As MnO 2 (MnO 2 -1 h, MnO 2 -2 h, MnO 2 -4 h, and MnO 2 -6 h) was prepared to degrade toluene, all the samples could completely catalyze toluene at the temperature of 225 °C. However, the MnO 2 -4 h showed the best catalytic effect at a lower temperature.