Biosynthesized CuO nano-platelets: Physical properties & enhanced thermal conductivity nanofluidics

This contribution reports for the first time, room temperature biosynthesis of p-type CuO nanoparticles carried out using Callistemon viminalis’ flower extracts as a chelating agent in a process that is entirely green. Room temperature X-ray diffraction, attenuated IR total reflection spectroscopy, X-ray photoelectron and Raman spectroscopy investigations confirmed the formation of single phase Tenorite bcc monoclinic CuO nanocrystals post annealing in air, at 500 °C. Photoluminescence spectroscopy with UV emissions at 356 nm (3.47 eV) and broad visible emissions at 418 nm, 561 nm, and 664 nm, support the formation in air, at 200 °C, of CuO nanoparticles with high surface-to-volume ratios and defects. As a direct application, the biosynthesized CuO nanoplatelet-containing powder dispersed in de-ionized water showed an enhancement of the thermal conductivity from 6% to 34% and a significant stability of the PVP stabilized CuO-water nanofluid.     

Optimization and detailed stability study on Pb doped ceria nanocubes for enhanced photodegradation of several anionic and cationic organic pollutants

A series of Pb doped CeO₂ nanocubes with seven different Pb loadings (2–12 mol%) were synthesized via modified hydrothermal technique. The prepared samples were characterized by XRD, XPS, FT-IR, TGA, SEM, HR-TEM, EDS and UV–Vis DRS analysis. According to XRD analysis, the crystalline structure of synthesized pure CeO₂ and Pb-doped CeO₂ samples are cubic structure. The ceria nanocubes showed an increase in amount of oxygen vacancies with increasing the dopant concentrations. When the doping level of Pb is 6 mol%, the optical band gap of Pb-CeO₂ is smaller than that of pure CeO₂ nanocubes. The HR-TEM results confirms the cubic structure of 6% Pb-CeO₂ with average crystallite size of about 15 nm. The photocatalytic ability of Pb-CeO₂ catalysts were studied by degrading several anionic and cationic organic pollutants like methylene blue (MB), methylene orange (MO), methylene red (MR), rhodamine B (RhB), reactive blue 160 (RB160), salicylic acid (SA), coumarin and phenol. The 6% Pb-CeO₂ nanocubes shows better photocatalytic performance against anionic dyes especially for MB. To find the optimum condition for better photocatalytic performance of 6% Pb-CeO₂ nanocubes, the photocatalytic process was conducted in different initial reaction conditions like reaction temperature, catalytic dosage, dye concentration and pH of the reaction solution. The stability and recyclability of 6% Pb-CeO₂ photocatalyst was studied by XRD, FT-IR and EDS analysis after 5 cycles of MB degradation. The hydroxyl radical estimation and trapping experiments were conducted to observe the photocatalytic mechanism process in 6% Pb-CeO₂ nanocubes. The perfect doping concentration for better organic pollutant degradation by Pb-CeO₂ is found to be 6 mol% of Pb.     

Visible light driven photocatalytic activity of ZnO/CuO nanocomposites coupled with rGO heterostructures synthesized by solid-state method for RhB dye degradation

Metal oxide frame works along with carbon materials have been attracting tremendous attention of researches as the potential materials for energy and environmental remediation. In the present work heterostructures of (ZnO/CuO)/rGO ternary nanocomposites were synthesized by solid-state method. The crystalline structure of the nanoparticles was obtained from the XRD analysis. Optical band gap of the ZnO nanoparticles (3.1 eV) is tuned to 2.8 eV in the synthesized (ZnO/CuO)/rGO ternary nanocomposites. Field emission scanning electron microscope images of the (ZnO/CuO)/rGO ternary nanocomposites revealed formation of well-developed flowers like morphology of (ZnO/CuO) nanoparticles on rGO sheets. Photoluminescence spectroscopy analysis of (ZnO/CuO)/rGO ternary nanocomposites show enhancement in the electron-hole pair separation and thereby diminishing electron-hole pairs recombination rates effectively. In the present work, the photocatalytic activity of the ZC₃G₁₅ ternary nanocomposites show 99% and 93% of degradation efficiency respectively against RhB dye and 4-chlorophenol for 20 min under visible light irradiation. Thus, the simple solid-state method provides the effective ternary nanocomposites heterostructures light harvesting material for energy and environmental remediation.     

Defluoridation in aqueous solution by a composite of reduced graphene oxide decorated with cuprous oxide via sonochemical

The World Health Organization (WHO) has recommended the fluoride level in drinking water (1.5 mg/L) and defluoridation of water is an essential to remove of fluoride from contaminated water. Hence, the effective and rapid adsorbent Cuprous oxide-reduced graphene oxide (Cu₂O-RGO) composite was developed to overwhelm this concern. Sonochemical approach was adopted for the synthesis of desirable composite which was further characterized by XRD, FTIR, SEM, and EDS. The optimized composite (30 mg) shown the significant adsorption capacity of 34 mg/g of F⁻ solution (pH = 9), 70% removal of F⁻ solution from real experiment and Freundlich model was fitted than Langmuir and Temkin isotherms. The experimental results corroborate that adsorbent is the most effective for removal of fluoride from its polluted water.     

Preparation and Electrochemiluminescence of a Graphene Oxide/Selenium Nanocomposite

A novel amplification system for electrochemiluminescence (ECL) was developed by combining graphene oxide (GO) and Se nanoparticles, in which the chitosan (CHIT) was used as improver. Based on a series of experiments, the influencing factors and mechanism for ECL emission were determined. Under optimal conditions, the GO/Se nanocomposite produced an intense ECL emission and maintained long-term ECL stability. Significantly, the electrode modified with GO/Se nanocomposite was used to detect the biomolecule dopamine (DA), and showed a linear range from 0.1 to 100 µM, with a detection limit of 0.025 µM.     

Transmission and small angle scattering of 15 MeV electrons in silicon single crystals

Abstract

A novel technique for the study of structural damage incurred by single crystal silicon targets during ion implantation is described. The method is based upon copper-decoration of the vacancy rich damaged region, followed by radiochemical measurement of the resulting copper distribution. Utilizing neutron activation, sharply peaked radiocopper profiles are obtained, which are believed to represent the depth distributions of large, relatively immobile defects such as vacancy clusters, voids, or crystalline faults. A more efficient decoration of isolated vacancy-type defects is realized when Wu is employed as a radioisotopic tracer in the decoration step, however, the rapid diffusivity of these smaller species leads to less sharply defined radiocopper profiles. Both the neutron activation and radiotracer modifications of the technique yield damage profiles which are significantly shallower than the corresponding implanted impurity profiles.     

Atmospheric pressure chemical vapour deposition of fluorine‐doped tin(IV) oxide from fluoroalkyltin precursors

Perfluoroalkytin compounds R_(4−n)Sn(R_f)_n (R = Me, Et, Bu, R_f = C₄F₉, n = 1; R = Bu, R_f = C₄F₉, n = 2, 3; R = Bu, R_f = C₆F₁₃, n = 1) have been synthesized, characterized by ¹H, ¹³C, ¹⁹F and ¹¹⁹Sn NMR, and evaluated as precursors for the atmospheric pressure chemical vapour deposition of fluorine‐doped SnO₂ thin films. All precursors were sufficiently volatile in the range 84–136 °C and glass substrate temperatures of ca 550 °C to yield high‐quality films with ca 0.79–2.02% fluorine incorporation, save for Bu₃SnC₆F₁₃, which incorporated <0.05% fluorine. Films were characterized by X‐ray diffraction, scanning electron microscopy, thickness, haze, emissivity, and sheet resistance. The fastest growth rates and highest quality films were obtained from Et₃SnC₄F₉. An electron diffraction study of Me₃SnC₄F₉ revealed four conformations, of which only the two of lowest abundance showed close F Sn contacts that could plausibly be associated with halogen transfer to tin, and in each case it was fluorine attached to either the γ‐ or δ‐carbon atoms of the R_f chain. Copyright © 2005 John Wiley & Sons, Ltd.     

外源一氧化氮对镉胁迫下番茄幼苗叶绿体保护作用的光谱学分析

镉（Cd）是重要的重金属污染源，一氧化氮（NO）是近年来发现的一种普遍存在于生物界的信使分子，研究表明其参与了植物对Cd胁迫的应答反应调控。文章用硝普纳（SNP）作为NO供体，向番茄幼苗喷洒100mol&#183;L^-1SNP1d后加入50mol&#183;L^-1Cd处理7d，取完全展开叶片，提取叶绿体进行光谱学研究，分别测定了叶绿体室温吸收光谱、叶绿体低温荧光光谱和DCPIP电子传递效率等指标，研究外源NO缓解Cd对叶绿体毒性的影响。结果发现，CA对叶绿素a、叶绿素b和类胡萝b素含量都有不同程度的降低，NO处理缓解了CA的影响，使叶绿体室温吸收光谱的吸收率提高；CA导致686nm处峰（PSII）偏移4nrn，峰值降低33％，734nm处峰值降低23％，外源NO缓解了Cd对光合系统的影响，使得叶绿体低温荧光光谱在686和734nm的峰值分别仅下降17％和100o；以DCPIP为人工电子受体，Cd处理的叶绿体中DCPIP还原速率较慢，光合电子传递（H2O→DCPIP）速率降低1．5倍，外源NO处理显著缓解了Cd对电子传递链的抑制，使其光合电子传递速率恢复到对照的水平。该研究可为NO处理增强植物对Cd胁迫的抗性提供理论依据。     

Nanoclusters of TiO2 wetted with gold

We combined scanning tunneling microscopy and density functional theory to establish the structure-functionality relationship for nanometer-sized defects on TiO₂(1 1 0). Three-angstrom high topographically distinct dots are ascribed to stoichiometric TiO₂ nanoclusters with low coordination numbers. The under-coordinated O atoms of the nanocluster, with surface O atoms, provide exceptionally strong binding sites for Au nanoparticles. Our atomistic model elucidates a number of characteristics salient to low temperature CO oxidation by Au nanoparticles.     

Band bending at the conducting polymer/indium tin oxide interfaces with and without ultraviolet treatment

In this study, the effect of ultraviolet treatment on the band bending at the poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)/indium tin oxide (PEDOT:PSS/ITO) interfaces were researched. The authors suggested that ultraviolet treatment could lead to a reduction in the band bending at the PEDOT:PSS/ITO interface, owing to the removal of carbon contamination at the ITO surfaces and a decrease in the number of the trap-states at the PEDOT:PSS/ITO interface.