Jaspal Singh; Kavita Sahu; Sini Kuriakose; Nishant Tripathi; D. K. Avasthi; Satyabrata Mohapatra
Abstract
Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, ...
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Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy and UV-visible absorption spectroscopy. X-ray diffraction studies showed that the as-deposited TiO2 thin films made up of anatase TiO2 nanoparticles transformed into anatase/ rutile mixed-phase TiO2 nanoparticles upon annealing. Field emission scanning electron microscopy and atomic force microscopy studies revealed growth of TiO2 nanoparticles from 16 nm to 29 nm upon annealing at 600 o C. The photocatalytic activities of the nanostructured TiO2 thin films were studied by monitoring photocatalytic degradation of methylene blue in water. Our results showed that the as-deposited nanostructured TiO2 thin films exhibited highly enhanced photocatalytic efficiency as compared to the annealed samples. The mechanism underlying the enhanced photocatalytic activity of nanostructured TiO2 thin film is tentatively proposed.
Jaspal Singh; Satyabrata Mohapatra
Abstract
Nanostructures of TiO2 were synthesized by a facile sol-gel method using pentanol as solvent. The effects of thermal annealing on the structural, optical and photocatalytic properties of as-synthesized TiO2 nanostructures have been studied using X-ray diffraction (XRD), atomic force microscopy (AFM), ...
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Nanostructures of TiO2 were synthesized by a facile sol-gel method using pentanol as solvent. The effects of thermal annealing on the structural, optical and photocatalytic properties of as-synthesized TiO2 nanostructures have been studied using X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and UV-visible absorption spectroscopy. XRD and Raman spectroscopy results revealed that the synthesized TiO2 nanostructures exist in anatase phase for annealing at temperatures up to 300 o C, while annealing at 600 o C led to the formation of TiO2 nanostructures in anatase/rutile mixed-phase. AFM studies revealed the presence of TiO2 nanorods, which showed a small decrease in aspect ratio upon annealing. The photocatalytic activity of nanostructured TiO2 samples was evaluated through sun light driven degradation of methylene blue (MB) dye in water. TiO2 nanorods in anatase/rutile mixed-phase in the sample annealed at 600 o C were found to exhibit the highest photocatalytic activity towards degradation of MB dye. The mechanism underlying the enhanced photocatalytic activity of TiO2 nanostructures in anatase/rutile mixed-phase is tentatively proposed.
Bandita Mohapatra; Reena Kaintura; Jaspal Singh; Sini Kuriakose; Satyabrata Mohapatra
Abstract
Stable aqueous dispersions with high concentration of silver nanoparticles were synthesized by a facile and green synthetic route by treating silver ions with aqueous Citrus limon extract, used as a reducing and capping agent. The formation and growth of silver nanoparticles, prepared by this simple ...
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Stable aqueous dispersions with high concentration of silver nanoparticles were synthesized by a facile and green synthetic route by treating silver ions with aqueous Citrus limon extract, used as a reducing and capping agent. The formation and growth of silver nanoparticles, prepared by this simple and convenient method, was monitored using UV-visible absorption spectroscopy. The effects of Ag concentration, Citrus limon extract concentration, in-situ and ex-situ pH variations upon NaOH addition on the structural, optical and plasmonic properties of the synthesized Ag nanoparticles were investigated. X-ray diffraction studies revealed the formation of Ag nanoparticles, whose morphology was studied using atomic force microscopy. UV-visible absorption studies revealed surface plasmon resonance (SPR) peak around 465 nm, confirming the presence of Ag nanoparticles. The SPR peak blue shifted along with significant enhancement in intensity with increase in Ag concentration and pH, due to the growth and increased aggregation of Ag nanoparticles. We have shown that addition of NaOH is a key to rapid biosynthesis of stable aqueous dispersions of high concentration of silver nanoparticles. This green synthetic route provides faster synthesis of silver nanoparticles with improved colloidal stability, which can be used in foods, cosmetics and biomedical applications.
