Search results for "Photocurrent"

Red Shift in the Light Absorption Threshold of Anodic TiO2 Films Induced by Nitrogen Incorporation

2014

Abstract Titanium foils were anodized in ammonium containing and ammonium free solutions in order to check the possibility of inducing nitrogen incorporation into anodic TiO 2 films. XPS spectra confirmed the presence of O-Ti-N bonds on the surface of the anodic films prepared in ammonium biborate electrolytes. In order to evidence the effect of nitrogen incorporation on the light absorption threshold, photoelectrochemical behavior of as-anodized and high temperature annealed films as a function of the anodizing electrolyte composition were investigated. A photocurrent tail at energies lower than the mobility gap of TiO 2 appeared for those films prepared in ammonium containing electrolytes…

Structural and Photocurrent Characterization of Anodic Oxides on Titanium

2010

The Influence of Thermal Treatment on the Electronic Properties of a-Nb2O5

2009

The effect of thermal treatments for 1h at 250{degree sign}C in air or under vacuum on the electronic structure of thick amorphous anodic niobia was characterized by electrochemical impedance, differential admittance (DA) and photocurrent spectroscopy (PCS). The analysis of anodized niobia has revealed that it behaves as a pure dielectric. The thermal treatment in air increases the value of the differential capacitance of the niobia sample. The effect is stronger when the thermal treatment is carried out in vacuum and can be cancelled out by reanodizing the oxide to the initial formation potential. In the case of thermally vacuum-treated sample, a behavior typical of semiconducting amorphou…

Photoelectrochemical study on anodic aluminum oxide films. Internal photoemission processes at the metal-oxide interface

1991

A photoelectrochemical investigation has been carried out on aluminum oxide films grown anodically at constant rate up to different thicknesses. Depending on the potential both anodic and cathodic photocurrents were observed at photon energies well below the optical bandgap expected for these layers. This finding is explained with the presence of internal photoinjection processes both for electrons and holes from the base metal into the oxide film. The analysis of the photocurrent spectra has given the threshold energies for both processes. The effect of the image force at the metal/oxide interface has been taken into account in order to derive the mobility gap of the films and the energeti…

Integration of a perovskite-based amplifier and photodetector system in rigid and solid substrates

2021

During the last years, organometallic lead halide perovskites (LHP) have been widely studied as outstanding materials for photovoltaics and photonics applications [1] . These emerging semiconductors are fabricated by cheap and straightforward solution process techniques on polycrystalline film of the compound CH 3 NH 3 PbX 3 (X=Cl, Br, I). Their outstanding properties of these films include large absorption coefficients above the bandgap, high electronic mobilities, high quantum yield of emission at room temperature or tunable band-gap with the composition [1] . In this work, we exploit the excellent light emitting and photodetection properties of CH 3 NH 3 PbI 3 thin films to integrate a w…

Synergistic effect between hydrodynamic conditions during Ti anodization and acidic treatment on the photoelectric properties of TiO2 nanotubes

2015

In the present work, the combined influence of controlled hydrodynamic conditions during Ti anodization and the acidic treatment with HClO4 on the photoelectric properties of mixed anatase/rutile TiO2 nanotubes has been studied. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FE-SEM), Confocal Raman Microscopy, electrochemical measurements (electrochemical impedance spectroscopy and Mott-Schottky analysis) and photoelectrochemical measurements. It has been observed that the use of hydrodynamic conditions increases the surface area of nanotubes, while acidic treatment enhances their conductivity. Besides, there is a clear synergistic effect between t…

Photoelectrocatalytic oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B3 by TiO2 nanotubes

2020

In this paper, the first photoelectrocatalytic (PEC) 3-pyridinemethanol oxidation to 3-pyridinemethanal and vitamin B-3 was investigated. To meet this aim, efficient nanotube structured TiO2 on a Ti plate as a photoanode was prepared by an anodic oxidation method in ethylene glycol and characterized by XRD, SEM, and photocurrent techniques. The effect of nanotube morphology, applied potential, Na2SO4 concentration, stirring speed of solution, and pH on the reaction activity and product selectivities were investigated. The TiO2 phase of all of the anodes was mainly the anatase one. The PEC activity, the intensity of the XRD peak and the photocurrent increased by increasing the nanotube lengt…

Control on the morphology and photoelectrocatalytic properties of ZnO nanostructures by simple anodization varying electrolyte composition

2021

Abstract Zinc oxide nanostructured electrodes were successfully synthesized by a simple method of anodization in different aqueous bicarbonate electrolytes. The influence of the anodization electrolyte composition (by adding ethanol or glycerol) on the morphology and the photoelectrocatalytic properties of the zinc oxide electrodes was studied, as well as the combined effect of anodizing under controlled hydrodynamic conditions. Field Emission Scanning Electron Microscope (FE-SEM) images of the ZnO electrodes showed that the addition of ethanol or glycerol to the anodization electrolyte resulted in changes in size and morphology of the nanostructures. Thus, ZnO nanowires, nanotubes, nanospo…

The influence of nitrogen incorporation on the optical properties of anodic Ta2O5

2012

Abstract Anodic oxides were grown on sputter-deposited Ta in different aqueous solutions. A photoelectrochemical investigation was performed in order to estimate the band gap of the films as a function of the anodizing bath composition and formation voltage, i.e. thickness. Photoelectrochemical results provided evidence of sub-band gap photocurrent for films formed in a bath containing ammonium ions at pH 9. Elemental depth profiles obtained by glow discharge optical emission spectroscopy revealed the presence of nitrogen species in the outer part of the anodic films, which is bonded to Ta according to XPS analysis. A mechanism of nitrogen incorporation is proposed in order to account for t…

Enhancement of visible light photoelectrocatalytic activity of ZnO(core)/TiO2(shell) composite by N-doping and decorating with Au0 nanoparticles

2017

Abstract The composites consisting of ITO-supported ZnO nanorods covered with TiO2 shell were doped with nitrogen and decorated with gold nanoparticles in order to improve their photocatalytic activity under visible light. N-doped TiO2 (TiO2(N)) was prepared under mild conditions through a simple sol-gel synthesis in the presence of NH4Cl. Such procedure results in formation of a highly porous shell of TiO2(N) on the ZnO nanorods. The gold nanoparticles (AuNPs) of the size 7–25 nm were grafted onto the surface of TiO2 as well as TiO2(N) by a photodeposition method from aqueous solution of [AuCl(4-x)(OH)x]− precursor at pH 6.7. The composition and microstructure of the prepared samples were …