Emergent chiroptical properties in supramolecular and plasmonic assemblies

2021 ◽  
Author(s):  
N. S. Shahana Nizar ◽  
Meleppatt Sujith ◽  
K. Swathi ◽  
Cristina Sissa ◽  
Anna Painelli ◽  
...  
Keyword(s):  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Comprehensive Description ◽  
Chiroptical Properties ◽  
Uv Visible

This tutorial provides a comprehensive description of the origin of chiroptical properties of supramolecular and plasmonic assemblies in the UV–visible region of the electromagnetic spectrum.

scholarly journals Photocatalytic degradation of Phenol, Catechol and Hydroquinone over Au-ZnO nanomaterials

2019 ◽  
pp. 24-32
Author(s):  
Julie Joseane Murcia Mesa ◽  
Jonny Alberto García Arias ◽  
Hugo Alfonso Rojas Sarmiento ◽  
Oswaldo Eliecer Cárdenas González
Keyword(s):  
Photocatalytic Activity ◽  
Phenolic Compounds ◽  
Physicochemical Properties ◽  
Catalytic Reaction ◽  
Phenol Degradation ◽  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Zno Nanomaterials ◽  
Target Molecules ◽  
Uv Visible

Au-ZnO nanomaterials were tested in photodegradation reactions performed under UV-Visible light; Phenol,  Catechol and Hydroquinone were selected as target molecules, and it was found that Hydroquinone is the most sensitive molecule to be degraded under illumination. The Au addition significantly increases the photocatalytic activity of ZnO in the degradation of the phenolic compounds and the Au content is an important factor influencing the physicochemical properties of the nanomaterials synthesized and therefore the effectiveness of the photocatalytic treatment. The highest effectiveness in the phenolic compounds elimination was achieved by using ZnO modified by the addition of 2 wt.% of gold, this is due to the highest absorption of this material in the visible region of the electromagnetic spectrum. By HPLC analyzes, it was determined that the degradation route of the phenolic compounds depends on the photocatalyst employed in the catalytic reaction and on the substrate to be degraded, thus, Phenol degradation takes place by formation of more intermediate compounds than the observed in Catechol or Hydroquinone photodegradation.

scholarly journals Electronic, Structural, and Optical Structure of Mono-Doped and Co-Doped (210) TiO2 Brookite Surfaces for Application in Dye-Sensitized Solar Cells—A First Principles Study

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3918
Author(s):  
Ratshilumela S. Dima ◽  
Lutendo Phuthu ◽  
Nnditshedzeni E. Maluta ◽  
Joseph K. Kirui ◽  
Rapela R. Maphanga
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
Dye Sensitized Solar Cells ◽  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Doped Tio2 ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Co Doped ◽  
Optical Structure

Titanium dioxide (TiO2) polymorphs have recently gained a lot of attention in dye-sensitized solar cells (DSSCs). The brookite polymorph, among other TiO2 polymorphs, is now becoming the focus of research in DSSC applications, despite the difficulties in obtaining it as a pure phase experimentally. The current theoretical study used different nonmetals (C, S and N) and (C-S, C-N and S-N) as dopants and co-dopants, respectively, to investigate the effects of mono-doping and co-doping on the electronic, structural, and optical structure properties of (210) TiO2 brookite surfaces, which is the most exposed surface of brookite. The results show that due to the narrowing of the band gap and the presence of impurity levels in the band gap, all mono-doped and co-doped TiO2 brookite (210) surfaces exhibit some redshift. In particular, the C-doped, and C-N co-doped TiO2 brookite (210) surfaces exhibit better absorption in the visible region of the electromagnetic spectrum in comparison to the pure, S-doped, N-doped, C-S co-doped and N-S co-doped TiO2 brookite (210) surfaces.

Hydrothermal Synthesis of Nanosized Titania Photocatalysts Using Novel Water-Soluble Titanium Complexes

2007 ◽  
Vol 124-126 ◽  
pp. 723-726 ◽  
Author(s):  
Makoto Kobayashi ◽  
Koji Tomita ◽  
Valery Petrykin ◽  
Shu Yin ◽  
Tsugio Sato ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Single Phase ◽  
Visible Region ◽  
Water Soluble ◽  
No Oxidation ◽  
Nano Particles ◽  
Titanium Complexes ◽  
Uv Visible

Highly crystalline titania nano-particles were synthesized by hydrothermal method using novel stable water-soluble titanium complexes. It was confirmed that single phase anatase, rutile and brookite, which can be rarely synthesized as a single phase, can be obtained by varying the ligand in the complex and pH of the aqueous solution. TEM observations and BET specific surface area measurements had shown that these samples consisted of nanosized particles of 5~200 nm and had high specific surface areas of 25~150 m2/g. According to UV-visible diffuse reflectance spectra, these titania samples absorbed light in the visible region (λ > 400 nm). Photocatalytic activities in NO oxidation reaction exhibited by synthesized titania powders under the irradiation by UV- visible light were higher than the activity of the commercial TiO2 photocatalyst P25 (Degussa). Especially, under illumination by only visible light of above 510 nm wavelength, photocatalytic activity of the obtained specimens exceeded that of P25 more than four times. We also clearly demonstrated that single phase brookite had high photocatalytic activity for NO oxidation.

Eco-Friendly Green Synthesis of MgO Nanoparticles from Zingiber Officinale(Ginger) Root Extract and its Antibacterial Application

2021 ◽  
Vol 9 (VI) ◽  
pp. 4219-4222
Author(s):  
R. D. More
Keyword(s):  
Green Synthesis ◽  
Pathogenic Bacteria ◽  
Visible Region ◽  
Cost Effective ◽  
Zingiber Officinale ◽  
Band Gap Energy ◽  
Root Extract ◽  
Mgo Nanoparticles ◽  
Medicinal Value ◽  
Uv Visible

In this study preparation of MgO nanoparticles using Zingiber officinale (ginger) aqueous root extract by using green method. The green synthesis approaches are recognized by many scientists due to its cost effective, simple, eco-friendly. The stability and reduction of Mg+2 ions to MgO nanoparticles were characterized by UV-Visible spectroscopic analysis. From UV-Visible spectroscopy, higher band gap energy of 7.8 eV is obtained in the near visible region at the wavelength of 300 nm. The Zingiber officinale (ginger) root extract act as reducing agent for stabilization of particle size as well as medicinal value result showed a significant antibacterial activity against pathogenic bacteria, E.Coli.and S.aureus. The present investigation deals with the green synthesis of MgO nanoparticles and its antibacterial effect on selected bacteria.

Photoreduction of Dye with Noble Metal Gold Permeated with Metal Oxide Titania

2020 ◽  
Vol 20 (6) ◽  
pp. 3896-3901 ◽  
Author(s):  
Jyoti Bansal ◽  
A. K. Hafiz ◽  
Shailesh Narain Sharma
Keyword(s):  
Metal Oxide ◽  
Noble Metals ◽  
Irradiation Time ◽  
Visible Region ◽  
Visible Absorption ◽  
Photo Degradation ◽  
Sunlight Irradiation ◽  
Tunable Bandgap ◽  
Photo Response ◽  
Uv Visible

Photoactive degradation of textile malachite green (MG), methylene blue (MB) dyes has been permeated on metal oxide TiO2 nanoparticles under sunlight. Semiconductor photocatalysis is a promising method for removal of toxic chemicals from wastewater produced by industry. Due to tunable bandgap, TiO2 among various semiconductor studied mostly. Large band gap (UV active) and recombination of exciton in TiO2 less active in photo degradation. Noble metals such as gold nanoparticles deposited on TiO2 surface increased the optical activity and to shift optical response to visible region. Degradation detail has been carried out by characterisation such as XRD, UV-Vis, PL, TEM, and SEM for MG and MB textile dyes under sunlight irradiation. UV-visible absorption spectra and PL spectra shows that photo-response of as prepared sample is extended from UV to visible region. PL intensity decreases with increases in concentration of Au nanoparticles, decreases in intensity in optical spectra of Au–TiO2 composites shows that charge transfer process dominates. Au–TiO2 plays an essential role in enhancing photocatalytical activity. Decolorization optimization depends on catalyst concentration, Dye concentration, light intensity and, irradiation time.

scholarly journals Homeopathic Potencies May Possess an Electric Field(-like) Component: Evidence from the Use of Encapsulated Solvatochromic Dyes

Homeopathy ◽  
2019 ◽  
Vol 109 (01) ◽  
pp. 014-022
Author(s):  
Steven J. Cartwright
Keyword(s):  
Electric Field ◽  
Bathochromic Shift ◽  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Experimental Conditions ◽  
Fundamental Identity ◽  
Spectral Changes ◽  
Absorbance Change ◽  
Solvatochromic Dyes ◽  
Brooker’S Merocyanine

Background Homeopathic potencies have been shown to interact with a range of solvatochromic dyes to produce spectroscopic changes in the visible region of the electromagnetic spectrum. Furthermore, the nature of the changes observed under different experimental conditions is beginning to limit the number of possible hypotheses that can be put forward regarding the fundamental identity of potencies. Aims and Methods The present study uses β-cyclodextrins to encapsulate solvatochromic dyes of widely varying structures. The purpose of this approach is to de-couple the primary dye–potency interaction from any subsequent aggregation effects. Results Despite large differences in molecular structure between dyes, results show that potencies affect all dyes according to the same fundamental principles. Specifically, positively and negatively solvatochromic dyes collectively respond in opposite and complementary ways to potencies in accordance with the differential stabilisation of their excited and ground electronic states. Under the conditions of encapsulation, positively solvatochromic dyes display a bathochromic shift of, on average, 0.4 nm with a 2% absorbance change, and negatively solvatochromic dyes display a hypsochromic shift of, on average, 0.2 nm with a 1% absorbance change. This behaviour is only ever seen in two situations—where solvent becomes more polar or where an electric field is applied to solutions of dyes. Conclusions The conditions used in this and previous studies to investigate the interaction of potencies with solvatochromic dyes preclude increased polarity of solvent as being responsible for the observed effects and that an explanation in which potencies carry an electric field (or electric field-like) component is by far the more likely. From the magnitude of the spectral changes induced in the dye Brooker's merocyanine by Arsenicum 10M, an estimate of the strength of the postulated electric field of 1.16 × 107 V/m can be made, which is comparable with the potential difference across cell membranes.

Au Nanostructure-Decorated TiO2 Nanowires Exhibiting Photoactivity Across Entire UV-visible Region for Photoelectrochemical Water Splitting

Nano Letters ◽  
2013 ◽  
Vol 13 (8) ◽  
pp. 3817-3823 ◽  
Author(s):  
Ying-Chih Pu ◽  
Gongming Wang ◽  
Kao-Der Chang ◽  
Yichuan Ling ◽  
Yin-Kai Lin ◽  
...  
Keyword(s):  
Water Splitting ◽  
Visible Region ◽  
Photoelectrochemical Water Splitting ◽  
Tio2 Nanowires ◽  
Uv Visible

Functional helquats: helical cationic dyes with marked, switchable chiroptical properties in the visible region

2015 ◽  
Vol 51 (9) ◽  
pp. 1583-1586 ◽  
Author(s):  
Paul E. Reyes-Gutiérrez ◽  
Michael Jirásek ◽  
Lukáš Severa ◽  
Pavlína Novotná ◽  
Dušan Koval ◽  
...  
Keyword(s):  
Visible Region ◽  
Cationic Dyes ◽  
Styryl Dyes ◽  
Chiroptical Properties

Helically chiral styryl dyes with large ECD in the visible region are introduced.

Al-Au Heterogeneous Dimer-trimer Nanostructure for SERS

2020 ◽  
Vol 10 (1) ◽  
pp. 21-28
Author(s):  
Jyoti Katyal
Keyword(s):  
Field Distribution ◽  
Enhancement Factor ◽  
Extinction Spectrum ◽  
Visible Region ◽  
Field Enhancement ◽  
Spherical Shape ◽  
Resonance Wavelength ◽  
Time Step ◽  
Plasmonic Material ◽  
Uv Visible

: Tunability in resonance wavelength and the enhancement of the electromagnetic field intensities around the surface are two unique properties which make metal as a plasmonic material. A theoretical investigation on the LSPR and field enhancement for heterogeneous dimer–trimer metallic nanostructure by constituting Al and Au as two different plamsonic materials has been studied. Since electrons in Al exhibit free behavior for LSPR of Au, therefore, they influence the electric field magnitude generated by Au LSPR. Methods: The electromagnetic simulations reported in this paper were performed using the FDTD Solutions (version 7.5.1), a product of Lumerical Solutions Inc., Vancouver, Canada. We adopted a cubic Yee cell of 1 nm side and a time step Δt= 1.31•10-18 s, bounded by Courant condition. Results: The extinction spectrum shows LSPR peak over UV-visible region for isotropic nanostructure which shifts to NIR region for anisotropic shape nanostructure. The spherical shape hetero dimer nanostructure shows enhancement factor ~ 3.9 X 105 whereas it increases to ~ 6.2 X 106 for anisotropic shape at 610 nm. The field distribution corresponding to the trimer nanostructure reveals a large dipolar field distribution on each of the three nanoparticles, oscillating approximately in-phase. The spherical shape Al-Au-Al shows enhancement factor ~ 8.5 X 106 at 571 nm. The anisotropic shape increase the enhancement factor to ~ 2.4 X 107 at peak wavelength 700 nm i.e. tuning the plasmon wavelength towards NIR region. Conclusion: The tunability in plasmon wavelength and field enhancement factor has been evaluated for heterogeneous nanostructure over wider spectrum range i.e. DUV-Visible-NIR using Au-Al dimer and trimer nanostructure. The isotropic shape Au-Al hetero nanostructure shows larger enhancement in the UV-visible region, whereas the anisotropic shape nanostructure contributes towards the NIR region.

scholarly journals Preparation of Fe-DopedTiO2Nanotubes and Their Photocatalytic Activities under Visible Light

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Honghui Teng ◽  
Shukun Xu ◽  
Dandan Sun ◽  
Ying Zhang
Keyword(s):  
Visible Light ◽  
Visible Region ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Photocatalytic Activities ◽  
Ultrasonic Assisted ◽  
Uv Visible

Fe-doped TiO2nanotubes (Fe-TNTs) have been prepared by ultrasonic-assisted hydrothermal method. The structure and composition of the as-prepared TiO2nanotubes were characterized by transmission electron microscopy, X-ray diffraction, and UV-Visible absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of MO under visible light. The UV-visible absorption spectra of the Fe-TNT showed a red shift and an enhancement of the absorption in the visible region compared to the pure TNT. The Fe-TNTs were provided with good photocatalytic activities and photostability and under visible light irradiation, and the optimum molar ratio of Ti : Fe was found to be 100 : 1 in our experiments.

Sign in / Sign up

Export Citation Format

Share Document