Synthesis and characterization of nano-manganese dioxide and titanium dioxide

Nano sized manganese dioxide was synthesized using hydrothermal and co-precipitation methods by the reduction of hydrogen peroxide and potassium permanganate in respective methods. The co-precipitation method of synthesis was expanded to synthesize nano sized Titanium Dioxide. Characterization of the synthesized material was carried out by Elemental Analysis, X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), Infra Red Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). SEM analysis showed that the MnO2 prepared by hydrothermal method is made of spherical nanoparticles with sizes ranging from 15 nm--30 nm and the MnO2 prepared by co-precipitation method showed nanospheres of 20 nm--100 nm with several nano disks incorporated in these sphere of about 5 nm--50 nm in diameter. X-ray revealed that the MnO2 prepared by hydrothermal shows two different transitions from amorphous MnO2 to crystalline Mn2O3 and Mn2O3- Mn2O 3 Bixbyte with substantial amount of unreacted PVP in it, which is lost when heated to higher temperatures which are supported by data from DTA and TGA. In co-precipitation only one transition is observed that is from amorphous MnO2 to crystalline Mn2O3 Bixbyte and traces of unreacted PVP. Titanium Dioxide synthesized using PVP led to uniform spherical nano particles of 20 nm--100 nm with some unreacted PVP. X-Ray analysis shows one transition from amorphous TiO2 to crystalline TiO 2 Anatase. The TiO2 prepared without PVP is poorly crystalline to X-rays and identified as Brookite when heated to higher temperature. The SEM micrographs of TiO2 without PVP did not show any uniformity in particle size and shape distribution and lost homogeneity. The results from our study suggest that the clean, uniform and homogeneous nanoparticles can be prepared using a simple, room temperature, non-expensive co-precipitation method using PVP.