Synthesis and catalytic activity studies of α-MnO2 nanorodes, rutile TiO2 and its composite prepared by hydrothermal method

α-MnO2 exhibits an excellent catalytic activity in different chemical reactions, functions as enzyme alternative, as so-called artificial enzyme which is used in different applications such as industrial, environmental and biological applications (antibacterial activity). The current study, reports the synthesis of α-MnO2 and rutile TiO2 nanostructures using hydrothermal (autoclave) method by using precursors such as potassium permanganate (KMnO4) and titanium tetrachloride (TiCl4) respectively. The annealing of α-MnO2 was carried out between the temperature range 250-700°C. For the characterization of synthesized nanostructures i.e. surface and structure morphology was done through Atomic Force Microscope (AFM), X-ray diffraction (XRD), thermal analysis, Scanning Electron Microscopy (SEM), and molecular spectroscopic measurements. A novel colorimetric method was applied to study the catalytic activity for α-MnO2 which measured the gradual reduction in color density after reaction of KMnO4 solution or MnO2 nanoparticles with hydrogen peroxide (H2O2) at normal room temperature. The results indicated that α-MnO2 nanopowder showed the maximum activity at annealing temperature of 400 °C. The composite of MnO2−TiO2 in the ratio of 3:1 when annealed at 400 °C showed the decrease in catalytic activity in the decomposition reaction of H2O2 as compared to that of pure α-MnO2 nanopowder.