Two- and three-dimensional zinc oxide nanostructures and its photocatalytic dye degradation performance study

The zinc oxide (ZnO) nanostructures were synthesized using hydrothermal reaction technique at 180 degrees C with varying reaction time viz., 2, 4, 8 and 12 h and characterized with different spectroscopic/microscopic techniques. XRD indicate the formation of hexagonal phase of ZnO in all the prepared samples. The FESEM confirms the formation of hexagonal-shaped plate-like ZnO nanostructures having size in the range of 50 to 100 nm with the thickness of 10-15 nm, at 2 h reaction time. Further increase in the reaction time leads to increase in thickness of hexagonal ZnO plates resulting in formation of three-dimensional (3D) distorted spherical structures with facets. The photocatalytic activities were investigated by following degradation methylene blue (MB) dye. The ZnO prepared at 8 h of reaction time shows highest MB degradation rate, the apparent rate constant is 3.3 x 10(-2) +/- 0.1 x 10(-2) min(-1), almost five times more than 4 h reaction time.