Synthesis, growth mechanism and photocatalytic properties of nickel oxide (NiO) nanoflower: a hydrothermal process

The present report explores the synthesis strategy of flower like Nickel Oxide (NiO) nanostructures from nanosheets as their building blocks in the presence of citric acid as surfactant. An easy and inexpensive hydrothermal technique was designed for the synthesis of NiO nanoparticles. The structural, morphological and compositional analyses were done by the techniques such as X-ray Diffraction, Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray Analysis respectively and growth mechanism of the NiO nanostructure was also dealt in detail. Diffraction pattern confirms that the prepared NiO is belongs to the face cantered cubic structure. The average crystalline size was obtained by Debye Scherrer formula and the values (8 nm, 9 nm, 7 nm and 7.5 nm for NiO nanoflowers synthesized with 0.5 g, 1 g, 1.5 g and 2 g of citric acid respectively) are comparable with the size obtained by the Williamson Hall plot method. Morphological analysis confirms the formation of nanosheets constituted floral microspheres with a diameter ranging from 750 nm to 850 nm. Elemental analysis proves the presence of Ni and O and its purity. The 750 nm sized, regularly arranged NiO nanoflowers were subjected to photocatalytic degradation of Methylene Blue (MB) and Rhodamine 6G (Rh 6G) under Ultra Violet irradiation and bestow the effective degradation efficiency (76.5% and 92.6% respectively). The photodegradation mechanism was discussed based on the position of conduction and valence bands.