Highly efficient photocatalytic degradation of organic dyes by Cu doped ZnO nanostructures.

Copper doped ZnO nanostructures have been synthesized by a facile wet chemical method. Structural properties of as-synthesized nanomaterials have been studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy, while UV-visible absorption spectroscopy and Raman spectroscopy have been used to study their optical properties. Sunlight driven photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes in water was used to evaluate the photocatalytic activities of Cu doped ZnO nanostructures using UV-visible absorption spectroscopy. The results showed that there is an optimum Cu doping level which leads to the highly enhanced photocatalytic activity of Cu doped ZnO nanostructures, as compared to pure ZnO nanostructures. A mechanism for the enhanced photocatalytic activity of Cu-ZnO nanostructures is tentatively proposed. The enhanced photocatalytic activity of Cu-ZnO nanostructures is attributed to the combined effects of improved separation of photogenerated charge carriers due to optimal Cu doping in ZnO nanostructures and the formation of ZnO-CuO nanoheterojunctions.

Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO-CuO nanocomposites prepared by carbothermal evaporation method.

ZnO-CuO nanocomposite thin films were prepared by carbothermal evaporation of ZnO and Cu, combined with annealing. The effects of 90 MeV Ni(7+) ion irradiation on the structural and optical properties of ZnO-CuO nanocomposites were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-visible absorption spectroscopy and Raman spectroscopy. XRD studies showed the presence of ZnO and CuO nanostructures in the nanocomposites. FESEM images revealed the presence of nanosheets and nanorods in the nanocomposites. The photocatalytic activity of ZnO-CuO nanocomposites was evaluated on the basis of degradation of methylene blue (MB) and methyl orange (MO) dyes under sun light irradiation and it was observed that swift heavy ion irradiation results in significant enhancement in the photocatalytic efficiency of ZnO-CuO nanocomposites towards degradation of MB and MO dyes. The possible mechanism for the enhanced photocatalytic activity of ZnO-CuO nanocomposites is proposed. We attribute the observed enhanced photocatalytic activity of ZnO-CuO nanocomposites to the combined effects of improved sun light utilization and suppression of the recombination of photogenerated charge carriers in ZnO-CuO nanocomposites.

Facile synthesis of Ag-ZnO hybrid nanospindles for highly efficient photocatalytic degradation of methyl orange.

Highly photocatalytically active Ag nanoparticle decorated ZnO nanospindles were synthesized by a facile wet chemical method. The structural and optical properties of the as-synthesized materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) with energy dispersive X-ray spectroscopy, UV-visible absorption spectroscopy and Raman spectroscopy. The photocatalytic activity of these nanostructures was evaluated by analyzing sunlight driven degradation of methyl orange (MO) dye and it was observed that Ag nanoparticle modified ZnO nanospindles show significantly enhanced photocatalytic activity for degradation of MO, as compared to ZnO nanospindles. We attribute the observed enhanced photocatalytic activity of Ag nanoparticle decorated ZnO nanospindles to their improved sunlight utilization efficiency and the efficient suppression of recombination of photogenerated charge carriers due to the electron scavenging action of Ag nanoparticles and the interfacial electron transfers due to the Schottky junction between Ag nanoparticles and ZnO nanospindles.

Enhanced photocatalytic activity of Ag-ZnO hybrid plasmonic nanostructures prepared by a facile wet chemical method.

We report the synthesis of Ag-ZnO hybrid plasmonic nanostructures with enhanced photocatalytic activity by a facile wet-chemical method. The structural, optical, plasmonic and photocatalytic properties of the Ag-ZnO hybrid nanostructures were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV-visible absorption spectroscopy. The effects of citrate concentration and Ag nanoparticle loading on the photocatalytic activity of Ag-ZnO hybrid nanostructures towards sun-light driven degradation of methylene blue (MB) have been investigated. Increase in citrate concentration has been found to result in the formation of nanodisk-like structures, due to citrate-assisted oriented attachment of ZnO nanoparticles. The decoration of ZnO nanostructures with Ag nanoparticles resulted in a significant enhancement of the photocatalytic degradation efficiency, which has been found to increase with the extent of Ag nanoparticle loading.

Enhanced photocatalytic activity of Co doped ZnO nanodisks and nanorods prepared by a facile wet chemical method.

Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile wet chemical method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.

Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method.

Flower-like ZnO nanostructures were synthesized by a facile wet chemical method. Structural, optical and photocatalytic properties of these nanostructures have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV-vis absorption spectroscopy. SEM and TEM studies revealed flower-like structures consisting of nanosheets, formed due to oriented attachment of ZnO nanoparticles. Flower-like ZnO structures showed enhanced photocatalytic activity towards sun-light driven photodegradation of methylene blue dye (MB) as compared to ZnO nanoparticles. XRD, UV-vis absorption, PL, FTIR and TEM studies revealed the formation of Zn(OH)2 surface layer on ZnO nanostructures upon ageing. We demonstrate that the formation of a passivating Zn(OH)2 surface layer on the ZnO nanostructures upon ageing deteriorates their efficiency to photocatalytically degrade of MB.