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Multicomponent hybrid nanostructures exhibit multifunctional properties and synergistic performance which make them attractive materials for environmental applications. We have fabricated magnetic Au@CoFe2O4-ZnO hybrid plasmonic nanostructures using simple wet chemical route combined with photodeposition and studied their photocatalytic performance towards decomposition of synthetic dyes. XRD, FESEM and Raman were used to examine the structure and morphology of the prepared nanostructures and UV–visible spectroscopy was used for photocatalytic measurements. The solar-responsive photocatalytic decomposition of synthetic dyes MB and MO was examined and results displayed the outstanding performance of Au loaded CoFe2O4-ZnO nanostructures over CoFe2O4-ZnO photocatalysts. The prepared Au@CoFe2O4-ZnO hybrid nanostructures with higher Au loading, the sample CU3, effectively decolorized MB dye in only 20 min of sunlight exposure, achieving an apparent rate constant of 0.062 min−1. For MO dye, the sample CU3 achieved 96.6% degradation in 60 min with an apparent rate constant of 0.022 min−1. Mechanistic studies related to radicals responsible for the photodecomposition were discussed and results revealed that ⋅OH radicals and hot holes play major roles in photodecomposition of pollutants. Overall, Au decorated CoFe2O4-ZnO nanostructures prepared using facile photodecomposition route with excellent recyclability and effortless magnetic recovery represent a promising photocatalyst material and is highly suitable photocatalyst for environmental remediation applications. [ABSTRACT FROM AUTHOR]

We report facile biosynthesis of Ag–ZnO nanohybrids consisting of Ag nanoparticles decorated ZnO nanobullets prepared by decorating wet chemically synthesized ZnO nanobullets with Ag nanoparticles through bioreduction of Ag + ions with aqueous extract of Piper nigrum fruits. The prepared nanomaterials were well characterized by FESEM, TEM, HRTEM, EDX, XRD, XPS, PL and UV–vis spectroscopy. FESEM and TEM analyses on the nanohybrids revealed ∼18 nm Ag nanoparticles decorating ZnO nanobullets with average size ∼48 nm. XRD results revealed hexagonal wurtzite ZnO with 22.4 nm crystallite size and FCC Ag with 18.7 nm crystalline size. Ag–ZnO nanohybrids exhibited strong antibacterial action against Escherichia coli , Bacillus oceanisediminis and Pseudomonas entomophila and efficiently inhibited their growth at 100 μg/mL, 50 μg/mL and 125 μg/mL, respectively. The molecular basis of antibacterial action of Ag–ZnO nanohybrids against E. coli was investigated using different biochemical and molecular assays. Addition of antioxidant histidine suppressed the antibacterial action of Ag–ZnO nanohybrids towards E. coli due to its ROS scavenging action. Bradford assay results showed enhanced protein leakage from Ag–ZnO nanohybrids treated E. coli , while TBARS assay results confirmed lipid peroxidation triggered by ROS. SEM on Ag–ZnO nanohybrids treated E. coli confirmed significant damage to the cell wall leading to morphology change. The antibacterial activity of Ag–ZnO nanohybrids against E. coli is mainly due to the ROS-induced oxidative stress, which caused enhanced lipid peroxidation, cell wall damage leading to significant protein leakage and DNA fragmentation. [ABSTRACT FROM AUTHOR]

Spinel ferrite ZnFe2O4 nanostructures have been prepared as sunlight responsive photocatalysts via facile co-precipitation method. The structural, morphological, and optical responses were diligently characterized using XRD, Raman spectroscopy, FESEM, and UV–Vis absorption spectroscopy, respectively. FESEM studies revealed nanoparticles and porous-like nanoparticle aggregates, found to be of cubic spinel ZnFe2O4 from XRD and Raman studies. Crystallite size varied from 5 to 13.6 nm, whereas band gap changed from 1.89 to 1.95 eV with CTAB concentration variation. ZnFe2O4 nanostructures were employed for sunlight-assisted photodegradation of organic pollutants such as MB, MG, and MO dyes in water. The synthesized ZnFe2O4 nanoparticle aggregates with porous-like morphology with crystallite size of 9.2 nm showed superior photocatalytic response and decomposed 80.4% of MB dye in only 40 min. The superiority of the porous-like ZnFe2O4 nanoparticle aggregates was mainly ascribed to its optimal crystallite size, narrower band gap, and improved sunlight utilization efficiency. A plausible mechanism of photocatalytic oxidation of dye supported by scavenger studies has also been proposed. The synthesized ZnFe2O4 nanostructures have easy magnetic recycling property along with excellent photocatalytic capability and hold potential for the treatment of contaminated water. [ABSTRACT FROM AUTHOR]

[Display omitted] Rare earth doping in ZnO is an efficient way to improve the photocatalytic performance. In the present work, Er doped ZnO nanospindles and nanorods were prepared through a simple cost effective wet chemical approach and were thoroughly characterized by FESEM, XRD, Raman spectroscopy, UV–vis-DRS, UV–vis absorption and PL spectroscopy. Nanospindle and nanorod-like morphologies of the fabricated samples were revealed by FESEM. XRD analyses revealed hexagonal wurtzite structure of Er doped ZnO nanostructures and confirmed Er doping into ZnO. PL studies showed increased defect concentration in ZnO nanostructures doped with Er ions. The photodegradation ability of nanostructures was investigated using cationic and anionic dyes and photodecomposition rate of 0.042 min−1 was achieved for MB decolorization using 0.5 % Er doped ZnO sample upon 32 min of solar light illumination. The probable photodecomposition mechanism supported by in-situ radical trapping experiments and repeatability test have also been discussed and results suggest that Er doped ZnO photocatalyst exhibit potential for use as commercial solar-active photocatalysts. [ABSTRACT FROM AUTHOR]

Catalytic transformation of nitroaromatic compounds in wastewater using nanostructured catalysts is a promising method for wastewater treatment. Here, we report a systematic study on morphology-dependent catalytic activity of CuO nanostructures for efficient reduction of 4-nitrophenol (4-NP) in water. The morphology of CuO nanostructures was controllably varied from nanorods, nanosheets and hierarchical 3D flower-like structures by simply varying ammonia concentration in a simple wet chemical approach. Catalytic transformation of toxic 4-NP into useful 4-aminophenol by the prepared nanostructured CuO samples were investigated. The impact of morphology on the catalytic activity of nanostructured CuO catalysts was examined. It was observed that hierarchical 3D flower-like CuO catalysts show enhanced catalytic activity as compared to nanorods and nanosheets. The origin of this morphology-dependent catalytic activity of CuO nanostructures is discussed. [ABSTRACT FROM AUTHOR]

Cabbage-type morphology of cupric oxide (CuO) and cuprous oxide (Cu2O) nanostructures were synthesized via a simple and cost-effective chemical approach. HRTEM, FESEM, XRD, UV–Vis absorption and photoluminescence spectroscopies were used to identify the structural, optical, morphological and catalytic properties of the prepared nanostructures. Phase of the prepared copper oxide nanostructures was well controlled by changing the concentration of glucose. The prepared cabbage-type Cu2O nanostructures showed exceptionally improved catalytic performance towards the reduction of toxic 4-nitrophenol into useful 4-aminophenol as compared to cabbage-type CuO nanostructures. Cabbage-type Cu2O nanostructures completely transformed 4-NP into 4-AP in just 5 min with excellent rate constant (0.587 min−1). The observed excellent catalytic activity of prepared cabbage-type Cu2O nanostructures indicates their potential use in catalytic applications. [ABSTRACT FROM AUTHOR]

Hybrid plasmonic nanostructures consisting of Ag nanoparticles decorated TiO nanorods with highly enhanced photocatalytic activity were synthesized by a facile wet chemical method. The structural, optical, plasmonic and photocatalytic properties of the synthesized Ag-TiO hybrid nanostructures were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible absorption spectroscopy. The photocatalytic activities of the as-synthesized Ag-TiO hybrid nanostructures were evaluated by studying sun light-driven photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes in water. The results showed that Ag-TiO hybrid nanostructures exhibit highly enhanced photocatalytic activity towards degradation of MB and MO dyes and the photocatalytic efficiency increased with increase in Ag nanoparticle loading. The mechanism underlying the highly enhanced photocatalytic activity of Ag-TiO nanohybrids is proposed. We attribute the observed enhanced photocatalytic activity of Ag-TiO hybrid nanostructures to the efficient separation of photogenerated charge carriers in TiO due to the electron scavenging action of Ag nanoparticles and the improved sun light utilization by the plasmonic nanohybrids originating from the surface plasmon resonance (SPR) absorption of Ag nanoparticles. [ABSTRACT FROM AUTHOR]

Nanocomposite thin films of Ag-SnO 2 were synthesized by simple thermal evaporation based vapor deposition method combined with thermal annealing. The morphological, structural, optical and plasmonic properties of the nanocomposite thin films were studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV–visible absorption spectroscopy. UV–visible absorption studies revealed surface plasmon resonance (SPR) peak at 421 nm confirming the presence of Ag nanoparticles in the nanocomposites. The annealed Ag-SnO 2 nanocomposites exhibited enhanced CO gas sensing properties including high sensitivity, fast response-recovery and good selectivity towards CO gas. A tentative mechanism for the enhanced CO gas sensing properties of Ag-SnO 2 nanocomposites is proposed. [ABSTRACT FROM AUTHOR]

Solar-driven highly efficient photocatalytic decomposition of toxic organic contaminants using magnetically separable α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO ternary hybrid nanodiscs is reported. α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO ternary hybrid nanostructures were synthesized by microwave-assisted co-precipitation and simple co-precipitation methods and well characterized by XRD, micro-Raman, FESEM and UV–vis spectroscopy. FESEM micrographs revealed nanodiscs in case of microwave-assisted co-precipitation whereas nanoparticles and their aggregates were formed under co-precipitation combined with calcination. XRD and Raman studies confirmed the hybrid nature of prepared α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO nanostructures. Photocatalytic performance of α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO hybrid nanostructures was investigated by carrying out the photodegradation of organic dyes MB and MG under solar light illumination. The prepared α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO ternary hybrid magnetic nanodiscs decomposed MB and MG dyes in only 32 and 24 min, respectively. α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO hybrid nanodiscs showed excellent photocatalytic performance together with reusability and easy magnetic separation demonstrating its suitability for solar-driven photocatalytic water purification applications. In-situ scavenger studies showed •OH radicals are the main active radicals in solar-driven photocatalysis by α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO nanodiscs. The tentative mechanism of growth of α-Fe 2 O 3 /ZnFe 2 O 4 /ZnO ternary hybrid nanodiscs and the photocatalytic mechanism are discussed. [ABSTRACT FROM AUTHOR]

This study has been endeavoured to investigate the potential of magnetically separable CoFe 2 O 4 –ZnO hybrid nanostructures towards the complete mineralization of organic pollutants. Facile co-precipitation method was performed to obtain CoFe 2 O 4 –ZnO nanostructures, which were well characterized. The structure, composition and morphology of the materials were confirmed via XRD, Raman, FESEM, TEM and HRTEM which revealed the successful formation of CoFe 2 O 4 –ZnO heterojunctions with particle-like morphology having size in range of 10.4–27.6 nm. The optical properties were studied using PL and DRS whereas UV–visible spectroscopy was utilized for examining photocatalytic performance. The photodegradation property of the prepared nanophotocatalysts was assessed by the decomposition of organic dyes and results showed that CoFe 2 O 4 –ZnO nanostructures exhibit highly enhanced performance over pristine CoFe 2 O 4 due to the high light utilization ability and heterojunction formation which delays the charge carrier recombination and improves the photodecomposition capability. Additionally, the novel photocatalyst recycled well up to four consecutive degradation cycles and photocatalytic mechanism supported by scavenger experiments was also proposed. This study provides sunlight responsive magnetically separable CoFe 2 O 4 –ZnO photocatalyst which efficiently achieves the goal of rapid purification wastewater. [ABSTRACT FROM AUTHOR]

We report on the effects of 8 MeV Si 3+ ion irradiation on the structural, morphological and optical properties of nanostructured SnO 2 thin films, prepared by a simple thermal evaporation method. The structural and morphological evolution of nanostructured SnO 2 thin films upon MeV ion irradiation was studied by X-ray diffraction (XRD) and atomic force microscopy (AFM), while the optical properties of the thin films were characterized by Raman spectroscopy and photoluminescence spectroscopy (PL). XRD studies revealed the presence of nanocrystals of orthorhombic SnO 2 and cubic Sn in the as-deposited thin films. AFM studies revealed growth of SnO 2 nanoparticles in the films upon MeV ion irradiation. PL studies on the 8 MeV Si ion irradiated nanostructured SnO 2 thin films revealed strong enhancement in the intensity of UV and visible emissions from SnO 2 nanostructures. [ABSTRACT FROM AUTHOR]

• Au/SnO 2 thin films were prepared by sputtering combined with thermal evaporation • FESEM and AFM studied revealed nanoparticles in the SnO 2 and Au/SnO 2 films. • Nanocrystalline SnO 2 , Au, Sn and Au-Sn alloy were revealed by XRD analysis. • PL studies revealed that Au decoration of SnO 2 film led to enhanced UV emission. We report significantly enhanced photoluminescence from hybrid nanostructured Au/SnO 2 thin films due to surface plasmons excited in Au nanoparticles decorating SnO 2 nanostructured thin film. Nanostructured thin films with Au nanoparticles decorated SnO 2 nanostructures were prepared by sputter deposition of ultrathin Au films following thermal evaporation of SnO 2 film. The effects of deposition of ultrathin film of Au nanoparticles on the morphology, structure and optical response of nanostructured SnO 2 film were investigated. Nanocrystalline SnO 2 , Au, Sn and Au-Sn alloy were revealed by XRD analysis. PL studies revealed that Au nanoparticle decoration of nanostructured SnO 2 film led to highly enhanced UV emission. The mechanism of strong enhancement of PL from nanostructured SnO 2 film is tentatively proposed. The coupling of excitonic emission from SnO 2 nanostructures and excited surface plasmons in Au nanoparticles led to the observed strong PL enhancement. The hybrid nanostructured Au/SnO 2 thin films with strong UV emission are promising for designing efficient optical and photoelectrical devices. [ABSTRACT FROM AUTHOR]

Nanostructured thin films of Cu 2 O–CuO with improved photocatalytic and catalytic activities were developed by RF magnetron sputtering. Thickness-dependent optical, structural, morphological, photocatalytic and catalytic performance of the Cu 2 O–CuO films were investigated using field emission scanning electron microscopy (FESEM), XRD, AFM, RBS, UV–Vis absorption, PL and X-ray photoelectron spectroscopy. FESEM analyses showed nanoparticles which increased in size from 7 to 13 nm with increase in sputter deposition time and were confirmed to be of Cu 2 O–CuO from Raman and XPS studies. Increase in thickness of Cu 2 O–CuO thin film from 7 to 50 nm led to increase in surface roughness, decrease in band gap and reduction in PL intensity. Cu 2 O–CuO thin films showed thickness-dependent enhanced photocatalytic and catalytic activities towards degradation of methylene blue, methyl orange and 4-nitrophenol from water. The enhanced light utilization capability, suppressed charge recombination and small crystallite size of the developed nanostructured Cu 2 O–CuO thin films are the key factors responsible for their enhanced photocatalytic and catalytic performance. [ABSTRACT FROM AUTHOR]

Nanostructured thin films of CuO were deposited on silica glass substrates using reactive DC magnetron sputtering technique. Microstructural, morphological, optical, catalytic and photocatalytic properties of the prepared CuO thin films were examined using FESEM, AFM, Rutherford backscattering spectrometry, XRD, XPS, UV–Vis absorption and PL spectroscopy. FESEM showed nanostructures in the thin films, which were confirmed to be of monoclinic CuO by XRD analysis. Substrate temperature variation (40 °C, 100 °C and 300 °C) was found to significantly alter the optical, morphological, photocatalytic and structural properties of the CuO nanostructured thin film coatings. FESEM and AFM analyses showed decrease in size of nanostructures and surface roughness increase with increase in substrate temperature. Increase in UV–Vis absorbance and PL intensity of CuO thin films with decrease in crystallite size were noticed as the substrate temperature was increased. The prepared nanostructured CuO thin films exhibited highly enhanced photocatalytic activities and degraded dyes (MB and MO) in water in just 40 min under solar exposure and catalytic transformation of 4-nitrophenol (4-NP) took place in just 15 min. The developed CuO nanostructured thin film coatings are very promising for large scale, practical and advanced catalytic reduction of toxic 4-NP and photocatalytic applications in solar driven water purification. [ABSTRACT FROM AUTHOR]

Nanocomposite thin films of SnO 2 –ZnO were prepared by carbothermal evaporation of mixture of Sn and ZnO without using any catalyst. The nanocomposite thin films were irradiated with 8 MeV Si 3+ ions at room temperature to fluence varying from 1 × 10 14 to 1 × 10 15 ions/cm 2 . Effects of MeV ion irradiation on the structural and optical properties of SnO 2 –ZnO nanocomposites were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy, Photoluminescence spectroscopy (PL) and Raman spectroscopy. XRD studies revealed the presence of Sn, SnO 2 and ZnO nanostructures in the as-deposited films. FESEM studies on the irradiated samples revealed the formation of ZnO nanosheets. A tentative growth mechanism underlying the formation of ZnO nanosheets is proposed. Ion irradiation resulted in a significant enhancement in the UV and defect emissions from ZnO and SnO 2 nanostructures in the nanocomposite. [ABSTRACT FROM AUTHOR]

• ZnFe 2 O 4 /ZnO hybrid nanostructures were synthesized by facile co-precipitation. • ZnFe 2 O 4 /ZnO hybrid nanostructures exhibited excellent photocatalytic performance. • ZnFe 2 O 4 /ZnO hybrid nanostructures degraded organic pollutants in only 24 min. • Mechanism of superior photocatalytic activity of ZnFe 2 O 4 /ZnO nanostructures is proposed. [Display omitted] ZnFe 2 O 4 /ZnO heterojunction photocatalysts have been fabricated via simple co-precipitation method and systematically characterized. The structural and morphological analyses using XRD, Raman and FESEM confirmed the formation of ZnFe 2 O 4 /ZnO hybrid nanostructures. The optical properties were analysed via UV–vis DRS, PL and UV–vis absorption spectroscopy. UV–vis DRS studies showed band gap variation from 1.91 to 2.07 eV. The visible light-driven photodegradation activity of the synthesized products was explored by decomposing toxic pollutants in water and the results showed that ZnFe 2 O 4 /ZnO hybrid nanostructures exhibit superior photodegradation performance over pristine ZnFe 2 O 4 nanostructures. The improved photocatalytic performance of ZnFe 2 O 4 /ZnO nanostructures is ascribed to efficient sunlight utilization ability and suppression of recombination of photoinduced charge carriers due to p-n nanoheterojunction formation. In addition, photodegradation mechanism supported with scavenger experiments has been proposed. Besides the excellent photoactivity, ZnFe 2 O 4 /ZnO hybrid nanostructures are outstandingly stable, recyclable and thereby exhibit an enormous potential for large scale photocatalytic applications. [ABSTRACT FROM AUTHOR]