Journal of Advances in Nanomaterials

7

Authors: Yongkui Huang, Zhiyuan Yang, Shuijin Yang, Yulin Xu

H3PW12O40/SiO2 was prepared by a sol-gel method, and sensitized by H2O2 solution. Their photocatalytic effects on degradation of organic dyes were investigated under simulated natural light irradiation. Degradation of methyl orange was used as a probe reaction to explore the influencing factors of the photodegradation reaction. After used continuously for five times, the catalytic activity of the photocatalyst is not any lower. The photodegradation of methyl orange, methyl red, methyl violet, rhodamine B, malachite green and methylene blue were also tested, and the degradation rate of dyes can reach 84.6 %~98.3 %. It was found that the photodegradation reaction belongs to the first-order kinetic reaction.

9

Authors: Praveen Kumar Singh, Soumya Mukherjee, Chandan Kumar Ghosh, Saikat Maitra

TiO2 nanoparticles were synthesized by sol-gel method from titanium tetra isopropoxide. Influence of heat treatment on structural and morphological properties of TiO2 nanoparticles was investigated by XRD and SEM. Spectral properties of the nanoparticles were investigated using FTIR, Raman spectroscopy, PL spectroscopy and UV–visible absorption spectroscopy. XRD analysis revealed the formation of mixed anatase and ruitle phase in the synthesized powder at 550oC and existence of only rutile phase at 750 and 900oC. The lattice parameters, crystallite sizes, volume of the unit cell, density and surface area of TiO2 nanoparticles were determined from XRD analysis. SEM analysis showed that the prepared nanoparticles were in the nano regime, nearly spherical and larger agglomerated at lower temperature. EDX analysis showed that the TiO2 composition obtained was near stoichiometric at lower temperature and the proportion of oxygen vacancy increased with the increase in temperature. The presence of Ti-O and Ti-O-Ti bonds was confirmed by FTIR spectra. PL spectroscopy showed that the change in surface states and presence of anatase and rutile phases of TiO2 were also responsible for exhibiting the change in PL intensity. UV–visible absorption spectra showed the shifting of absorption edge towards the higher wavelength with the increase in temperature while the corresponding energy band gap of semiconductor nanoparticles decreased. Change in Raman spectra with the increase in temperature was observed due to anatase to rutile phase transformation and with the increase in the particle size.

13

Authors: Nidhi Shah, Karan Bhangaonkar, Dipak V. Pinjari, Shashank T. Mhaske

CeO2/ZnO composite nanoparticles are synthesized by using in-situ precipitation method, without any stabilizers, via conventional i.e. non-ultrasound (NUS) and ultrasound-assisted processing technique (US). The structure, morphology, particle size and % weight loss of the synthesized nanoparticles were analyzed by using X-ray powder diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) to establish the formation of core shell type nanomaterials with an average particle size under 15 nm. The effectiveness of the synthesized core shell morphology of CeO2/ZnO (catalyst) for the photocatalytic degradation of Rhodamine B (RhB) dye has also been investigated. It has been observed that the catalysts prepared by sonochemical method exhibit higher photocatalytic activity as compared to the catalysts prepared by the conventional method. It was also found that the ultrasound-assisted technique is an energy efficient method as it saves more than 80% of energy along with a substantial reduction in reaction time, as compared to conventional synthesis technique.