Sol-gel synthesis and Microstructure Characterization of NiO-TiO 2 Semiconductor

Abstract

NiO-TiO 2 is a fascinating p-n semiconducting binary metal oxide with unique electronic and optical properties. The NiO-TiO 2 has been synthesized using complicated preparation methods and expensive precursors that hamper their large-scale production. The present study reports the preparation of NiO-TiO 2 semiconductor with improved physicochemical properties. NiO-TiO 2 samples were prepared through one-pot sol-gel synthesis process followed by sintering of the as-synthesized materials at temperatures ranging from 600 to 1000 °C. The role of thermal treatment and NiO content on the microstructures was exquisitely studied. The microstructure of the NiO-TiO 2 samples was examined by Raman spectroscopy, XRD, XRF, SEM-EDAX, high resolution TEM, and UV-visible DRS analyses. It was revealed that the calcination temperature and the NiO content were crucial factors influenced the crystallization temperature, phase transformation, particle size and optical properties of the obtained NiO-TiO 2 systems. The incorporation of NiO in the TiO 2 microstructure generated photoactive materials with band gap energies ranging from 2.5 eV to 2.8 eV. NiTiO 3 system was observed in the calcined samples due to interaction of NiO and TiO 2 . Therefore, in order to synthesize NiO-TiO 2 semiconductors with appealing physico-chemical properties the selection of precursors and optimization of the preparation method and calcination temperature are very important. The current study hence elucidates a facile one- pot sol-gel approach to synthesize homogeneous binary metal oxide systems with controlled morphology and crystal structure in the absence of additives.