Search results for "RAMAN"
showing 10 items of 1328 documents
Surface plasmon subwavelength optics.
2003
International audience; Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons- in particular their interaction with light-can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.
Novel tree-like WO3 nanoplatelets with very high surface area synthesized by anodization under controlled hydrodynamic conditions
2016
In the present work, a new WO3 nanostructure has been obtained by anodization in a H2SO4/NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disk Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FESEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area exposed to the electrolyte, leading to an outstanding enhancement of its photoelectrochemical activity. Obtained results show that the size of nanostructures and the percentage of electrode surface covered by…
Influence of electrolyte temperature on the synthesis of iron oxide nanostructures by electrochemical anodization for water splitting
2018
[EN] Iron oxide nanostructures are an attractive option for being used as photocatalyst in photoelectrochemical applications such as water splitting for hydrogen production. Nanostructures can be obtained by different techniques, and electrochemical anodization is one of the simplest methods which allows high control of the obtained morphology by controlling its different operational parameters. In the present study, the influence of the electrolyte temperature during electrochemical anodization under stagnant and hydrodynamic conditions was evaluated. Temperature considerably affected the morphology of the obtained nanostructures and their photoelectrochemical behavior. Several techniques …
Degradation of Diazinon based on photoelectrocatalytic technique using enhanced WO3 nanostructures: Mechanism and pathway
2021
[EN] In this work, a resistant and toxic pesticide called diazinon was degraded through the photoelectrocatalysis (PEC) technique using tungsten oxide (WO3) nanostructures, applying an external bias of 1VAg/AgCl and simulated solar illumination. For this, WO3 nanostructures have been synthesized using electrochemical anodization in 0.05 M hydrogen peroxide and 1.5 M of different acidic electrolytes: H2SO4, CH4O3S or HNO3. Morphology, composition and crystallinity of the samples were evaluated through Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and Raman Spectroscopy. Then, the photoelectrochemical properties of the samples were analyzed by Photo-Elect…
Template Electrochemical Growth and Properties of Mo Oxide Nanostructures
2014
This work is aimed at studying the growing process of nanostructures electrodeposited from molybdate aqueous solutions at different pH values into pores of polycarbonate membrane templates. The challenging issue was the opportunity to investigate a rather complex deposition process in a confined ambient, where electrochemical conditions are quite different from those usually established for deposition on a flat substrate. Nanostructures were grown from a bath containing Mo7O246– (NH4)6Mo7O24·4H2O) at different concentrations (50–100 g/L), at a constant cathodic current density of 2 mA/cm2 (electrodeposition area ∼8 cm2). Nanostructured deposit was characterized by XRD, EDS, Raman, XPS, and …
Fast-Response Single-Nanowire Photodetector Based on ZnO/WS 2 Core/Shell Heterostructures
2018
This work was supported by the Latvian National Research Program IMIS2 and ISSP project for Students and Young Researchers Nr. SJZ/2016/6. S.P. is grateful to the ERA.Net RUS Plus WATERSPLIT project no. 237 for the financial support. S.V. is grateful for partial support by the Estonian Science Foundation grant PUT1689.
Electrochemical formation of novel TiO2-ZnO hybrid nanostructures for photoelectrochemical water splitting applications
2020
[EN] In this study, hybrid ZnO-TiO2 nanostructures have been synthesised by means of a simple electrochemical anodisation of titanium and subsequently ZnO electrodeposition. The influence of Zn(NO3)(2) concentration and temperature during the electrodeposition process was evaluated. Different techniques were used to analyse the synthesised nanostructures, notably Field Emission Scanning Electron Microscopy (FE-SEM) with Energy-dispersive X-ray spectroscopy (EDX) and Confocal Microscopy with Raman spectroscopy coupled with an Atomic Force Microscope. Photoelectrochemical water splitting tests were also performed at the hybrid nanostructures. According to the results, the photoelectrochemical…
Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers
2016
In the race towards two-dimensional electronic and optoelectronic devices, semiconducting transition metal dichalcogenides (TMDCs) from group VIB have been intensively studied in recent years due to the indirect to direct band-gap transition from bulk to the monolayer. However, new materials still need to be explored. For example, semiconducting TMDCs from group IVB have been predicted to have larger mobilities than their counterparts from group VIB in the monolayer limit. In this work we report the mechanical exfoliation of ZrX2 (X = S, Se) from bulk down to the monolayer and we study the dimensionality dependence of the Raman spectra in ambient conditions. We observe Raman signal from bul…
Mg and In Codoped p-type AlN Nanowires for pn Junction Realization.
2019
Efficient, mercury-free deep ultraviolet (DUV) light-emitting diodes (LEDs) are becoming a crucial challenge for many applications such as water purification. For decades, the poor p-type doping and difficult current injection of Al-rich AlGaN-based DUV LEDs have limited their efficiency and therefore their use. We present here the significant increase in AlN p-doping thanks to Mg/In codoping, which leads to an order of magnitude higher Mg solubility limit in AlN nanowires (NWs). Optimal electrical activation of acceptor impurities has been further achieved by electron irradiation, resulting in tunnel conduction through the AlN NW p-n junction. The proposed theoretical scenario to account f…
The structural properties of GaN/AlN core-shell nanocolumn heterostructures.
2010
International audience; The growth and structural properties of GaN/AlN core-shell nanowire heterostructures have been studied using a combination of resonant x-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy experiments. For a GaN core of 20 nm diameter on average surrounded by a homogeneous AlN shell, the built-in strain in GaN is found to agree with theoretical calculations performed using a valence force field model. It is then concluded that for an AlN thickness up to at least 12 nm both core and shell are in elastic equilibrium. However, in the case of an inhomogeneous growth of the AlN shell caused by the presence of steps on the sides of the …