Sini Kuriakose

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

Summary 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.

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

Summary 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.

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

Summary ZnO–CuO nanocomposite thin films were prepared by carbothermal evaporation of ZnO and Cu, combined with annealing. The effects of 90 MeV Ni7+ 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.