Search results for "Photoelectrochemical"
showing 10 items of 38 documents
Structural Studies of Titanium Oxide Multilayers
2005
Multilayers of titanium oxide on conductive glasses (silica, covered with indium/tin and tin oxides) were obtained by different methods (from suspension, by sol–gel, by vacuum sputtering). X-ray diffraction and positron annihilation depth-resolved characterization of these samples are presented. The data allow us to determine optimal deposition parameters, in order to obtain the anatase phase, important in practical applications in photoelectrochemical cells.
Original Approach to Synthesize TiO2/ZnO Hybrid Nanosponges Used as Photoanodes for Photoelectrochemical Applications
2021
[EN] In the present work, TiO2/ZnO hybrid nanosponges have been synthesized for the first time. First, TiO2 nanosponges were obtained by anodization under hydrodynamic conditions in a glycerol/water/NH4F electrolyte. Next, in order to achieve the anatase phase of TiO2 and improve its photocatalytic behaviour, the samples were annealed at 450 degrees C for 1 h. Once the TiO2 nanosponges were synthesized, TiO2/ZnO hybrid nanosponges were obtained by electrodeposition of ZnO on TiO2 nanosponges using different temperatures, times, and concentrations of zinc nitrate (Zn(NO3)(2)). TiO2/ZnO hybrid nanosponges were used as photoanodes in photoelectrochemical water splitting tests. The results indi…
Influence of annealing atmosphere on photoelectrochemical response of TiO2 nanotubes anodized under controlled hydrodynamic conditions
2021
[EN] The influence of three annealing atmospheres (air, nitrogen and argon) and the use of controlled hydrodynamic conditions (from 0 to 5000 rpm) on morphological, structural, chemical and photoelectrochemical properties of TiO2 nanotubes have been evaluated. For this purpose, different characterization techniques have been used: Field Emission Scanning Electron Microscopy, Raman Confocal Laser Spectroscopy, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Incident Photon-to-electron Conversion Efficiency measurements, ultraviolet-visible absorption spectra, Mott-Schottky analysis and photoelectrochemical water splitting tests. According to the results, it can be concluded that both hy…
Segregation of copper oxide on calcium copper titanate surface induced by Graphene Oxide for Water splitting applications
2020
Abstract Photoelectrochemical cells (PEC) are promising devices for hydrogen production via sunlight energy. One of the important challenges in this area is to design photoactive electrodes able to absorb visible light. A good photoelectrochemical behavior depends on the presence of surface active sites to photogenerate current at the lower possible potential for water splitting. Recent investigations in this field are focusing on perovskite materials such as CaCu3Ti4O12 (CCTO) as visible light active electrode due its outstanding structure in which CCTO encloses in its structure a visible light absorbance component (CuO). The presence CuO on the material surface is mainly responsible for t…
The effect of hydration layers on the anodic growth and on the dielectric properties of Al2O3 for electrolytic capacitors
2014
Hydrous films were grown on high purity and cubicity Al foils for electrolytic capacitors in deionized water, ethylene glycol - deionized water and in glycerol - deionized water for different immersion times. According to the X-ray diffraction patterns the hydration treatment allowed to grow a pseudo boehmite layer on Al surface whose morphology is appreciably affected by the bath composition. Capacitance measurements and photoelectrochemical findings suggest that a more compact barrier layer forms during the immersion in alcohol containing solutions. The hydration in water allowed to save energy and to prepare more blocking oxide films. The beneficial effect of hydration in hot water on th…
Synergistic Use of Electrochemical Impedance Spectroscopy and Photoelectrochemical Measurements for Studying Solid State Properties of Anodic HfO2
2017
Within the past years, intense research has been carried out on HfO2 as high k material, promising candidate to replace SiO2 as gate dielectric in CMOS based devices (1), and as metal oxide for resistive random access memory (ReRAM) (2). For both technological applications compact, uniform and flat oxides are necessary, and a detailed understanding of their physical properties as a function of the fabrication conditions is strongly. Hafnia performance can be significantly influenced by carrier trapping taking place at pre-existing precursors states (induced by oxygen vacancies, interstitial ions, impurities acting as dopants), or by self-trapping in a perfect lattice, where the potential we…
Photoelectrochemical removal of chlorfenvinphos by using WO3 nanorods: Influence of annealing temperature and operation pH
2019
[EN] A visible-light driven photoelectrochemical degradation process has been applied to a solution polluted with the organophosphate insecticide chlorfenvinphos. Different WO3 nanosheets/nanorods have been used as photoanodes. These nanostructured electrodes have been fabricated by anodization of tungsten and, subsequently, they have been subjected to a thermal treatment (annealing). The combined influence of annealing temperature (400¿°C and 600¿°C) and operation pH (1 and 3) on the photoelectrocatalytic behavior of these nanorods has been examined through a statistical analysis. Morphological, structural and photoelectrochemical characterizations have also been carried out. The chlorfenv…
Physicochemical characterization and photoelectrochemical analysis of iron oxide films
2013
Iron oxide films with a nanoporous structure were grown by anodizing sputter-deposited Fe in a fluoride containing ethylene glycol solution and annealed under air exposure at different temperatures. X-ray diffraction and Raman spectroscopy allowed to identify the presence of hematite and/or magnetite after thermal treatment for films annealed at T ≥ 400 °C under air exposure. According to GDOES compositional depth profiles, the thermal treatment sensitively reduced the amount of fluoride species incorporated into the film during the anodizing process. A band gap value of ~2.0 eV was estimated for all the investigated layers, while a flat band potential dependent on both the growth condition…
Enhancement of calcium copper titanium oxide photoelectrochemical performance using boron nitride nanosheets
2020
International audience; Photoelectrochemical water splitting under visible light has attracted attention for renewable hydrogen production. Despite prevalent investigations, many challenges still hindered an efficient energy conversion, such as enhancing the reaction efficiency in visible light. Thus controlling the photoelectrode materials is an essential step in designing new materials for water splitting. CaCu3Ti4O12 (CCTO) has received great attention as photocatalyst under solar light due to its combined band gap as result of the presence in its structure of TiO2 active in UV light and CuO active under visible light. In this work, a cubic CCTO with different amount of exfoliated hexago…
Aqueous synthesis of Z-scheme photocatalyst powders and thin-film photoanodes from earth abundant elements
2018
Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP 2017/8