Modification at Lattice Scale for an Optimized Optical Response of Alx(ZnO)1-x Nanostructures

We report the systematic changes of nano-scaled featur es and optical properties in a promising transparent oxide material, namely, Al x (x = 0, 1, 2 and 5%) doped ZnO 1-x (AZO). Electron microscopy investigations revealed the alterations at lattice scale depending on th e presence of Al-content in ZnO nanostructures. Lat- tice spacings of 0.26 and 0.28 nm oriented along the (0002) and (10 1 0) planes, respectively, were attributed to euhedral-and facetted-structures of hexagonal-ZnO. Th e AZO samples were furthe r characterized by XRD, SEM, UV-vis spectrophotometry, Raman spectroscopy and photoluminescence studies. It has been shown that at a dopant concentration of 2% Al in ZnO, an optimal balance could be achieved between microstruc- ture and optical properties

Synthesis of Novel Double-Layer Nanostructures of SiC–WOxby a Two Step Thermal Evaporation Process

A novel double-layer nanostructure of silicon carbide and tungsten oxide is synthesized by a two-step thermal evaporation process using NiO as the catalyst. First, SiC nanowires are grown on Si substrate and then high density W18O49nanorods are grown on these SiC nanowires to form a double-layer nanostructure. XRD and TEM analysis revealed that the synthesized nanostructures are well crystalline. The growth of W18O49nanorods on SiC nanowires is explained on the basis of vapor–solid (VS) mechanism. The reasonably better turn-on field (5.4 V/μm) measured from the field emission measurements suggest that the synthesized nanostructures could be used as potential field emitters

Synthesis and Characterization of ZnO Nanowire–CdO Composite Nanostructures

ZnO nanowire–CdO composite nanostructures were fabricated by a simple two-step process involving ammonia solution method and thermal evaporation. First, ZnO nanowires (NWs) were grown on Si substrate by aqueous ammonia solution method and then CdO was deposited on these ZnO NWs by thermal evaporation of cadmium chloride powder. The surface morphology and structure of the synthesized composite structures were analyzed by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The optical absorbance spectrum showed that ZnO NW–CdO composites can absorb light up to 550 nm. The photoluminescence spectrum of the composite structure does not show any CdO-related emission peak and also there was no band gap modification of ZnO due to CdO. The photocurrent measurements showed that ZnO NW–CdO composite structures have better photocurrent when compared with the bare ZnO NWs

Novel heterostructure of CdS nanoparticle/WO3 nanowhisker: Synthesis and photocatalytic properties

A novel heterostructure of CdS nanoparticles/WO3 nanowhiskers was synthesized using a simple two-step process; thermal evaporation and chemical bath deposition. First, WO3 nanowhiskers (NWs) were grown on a tungsten substrate by thermal evaporation of WO3 powder in a tube furnace at 1050 degrees C. Sequentially, CdS nanoparticles (NPs) were deposited on WO3 nanowhiskers by chemical bath deposition. CdS nanoparticles modified WO3 nanowhiskers showed enhanced visible light absorption compared to bare WO3 nanowhiskers. The photocatalytic activity was studied by the photodegradation of methylene blue. CdS NP/WO3 NW heterostructures showed remarkably enhanced photodecomposition efficiencies compared to bare WO3 nanowhiskers

Effect of Chelating Agents on the Structural, Optical, and Dye-Degradation Properties of Tungsten Oxide Nanoparticles

A simple co-precipitation method was used to create pure tungsten oxide (WO3) nanoparticles using phthalic acid, citric acid, and oxalic acid as chelating agents. The influences of chelating agents on the structural, morphological, and optical properties were investigated. X-ray diffraction (XRD) patterns of WO3 nanoparticles showed the existence of combined phase of anorthic-monoclinic for all the samples, and the crystalline size was found to be reduced while using oxalic acid. The vibrational band observed in the region around (500–800 cm−1) in the FTIR spectra indicates the formation of WO3 nanoparticles. SEM images revealed the formation of WO3 agglomerates. The energy-dispersive X-ray (EDX) spectra of the WO3 nanoparticles confirmed the purity of synthesized nanoparticles. The enhanced light-absorption ability of oxalic-acid-assisted WO3 nanoparticles are inferred from the decreased band gap energy in UV–vis absorption spectra. The PL spectra showed emission in both the UV and visible regions. The optimized reaction parameters for obtaining high catalytic efficiency are identified by varying the concentrations of oxidant, catalyst, and dye during the catalytic reaction. The synthesized WO3 nanoparticles exhibited better catalytic degradation of CV than MB and RB dyes even with the lesser quantity of catalyst material

Phase Transformation and Evolution of Localized Surface Plasmon Resonance in Cu_2–<i>x</i>S Thin Films Deposited at 60 °C

Cu_2–<i>x</i>S (0 ≤ x ≤ 1) thin films deposited at low temperatures (<95 °C) have rich polymorphs due to small differences in Gibbs free energy of formation, which is critical for understanding their fundamental properties. In this work, phase transformation from djurleite to covellite is obtained by simple chemical bath deposition (CBD) without using oxidizing/reducing agents. Cu_2–<i>x</i>S thin films synthesized using cetyltrimethylammonium bromide as a surfactant at 60 °C for different deposition time exhibit red shift in optical absorption due to quantum size effect and blue shift in localized surface plasmon resonance in the near-infrared region originating from increased copper vacancy. The surface morphology of the Cu_2–<i>x</i>S thin films is influenced by the surfactant, which in turn alters the optoelectronics properties. The preferential bonding between Cu and S is determined by hydrolysis of thioacetamide to release sulfides (S^2–) and disulfides (S₂^2–) and the kinetics to reduce Cu²⁺ to Cu⁺ leading to mixed phase formation and an increase in surface to volume ratio. Through X-ray photoelectron spectroscopy and X-ray absorption near edge structure analysis, it is confirmed that both Cu²⁺ and S^2– are reduced with time of deposition and form covellite Cu–S₂^2––Cu bonds

Optimization Control on Growth Morphology, Lattice Scale Features and Optical Response of Al-Incorporated ZnO Nano-Needles

A simple approach to synthesize zinc oxide nano-needles using aluminum incorporation at different concentrations (0, 0.5, 2, 5% Al) is reported and a detailed real and reciprocal space imaging is performed employing scanning as well as high resolution transmission electron microscopes which revealed the morphological alterations and provided a comprehensible representation of evolution of fascinating nanostructures, depending on Al-content in bare ZnO. Subsequently optical investigations were carried out by employing UV-Vis, PL and FT-IR spectroscopy inferred to a basis for significant structure-property correlation leading for 2% Al incorporation in ZnO matrix as the highest quality luminescent material