Impedance behaviour of anodic TiO2 films prepared by galvanostatic anodisation and powerful pulsed discharge in electrolyte
authors Poznyak, SK; Lisenkov, AD; Ferreira, MGS; Kulak, AI; Zheludkevich, ML
nationality International
journal ELECTROCHIMICA ACTA
author keywords Anodic films; Titanium dioxide; Pulsed discharge; EIS; Photocurrent
keywords PHASE ELEMENT BEHAVIOR; OXIDE-FILMS; PASSIVE FILMS; GROWTH-RATE; ELECTROCHEMICAL CHARACTERIZATION; PHOTOELECTROCHEMICAL BEHAVIOR; SEMICONDUCTING-FILMS; EIS CHARACTERIZATION; TITANIUM ELECTRODES; CORROSION BEHAVIOR
abstract Anodic titania films were prepared on titanium by novel powerful pulsed discharge technique which confers extremely high rates of the film growth. Electrochemical impedance spectroscopy (EIS) has been used as a main method to study the structure and semiconductive properties of the anodic oxide films grown in sulphuric acid electrolyte. The EIS results are supported with microscopic observations and photoelectrochemical measurements. For comparison, the properties of the anodic films prepared by the conventional galvanostatic anodisation in the same electrolyte were also examined. For modeling of the impedance spectra, different equivalent circuits taking into account the effects of space charge region and film structure were proposed. Thinner anodic films (d approximate to 25 nm) prepared by both methods demonstrate a similar behaviour characteristic of amorphous barrier-type oxide, whereas a very significant difference in the properties of the films produced by the two different approaches was revealed for thicker films (d = 70-120 nm). The discharge-prepared films in this range of thickness are composed by one compact layer with a relatively low concentration of ionised donors (N-d = (1-3) x 10(18) cm(-3)) estimated from Mott-Schottky plots, whilst the conventional galvanostatic method leads to the development of two-layer films consisting of an inner compact layer and a nanoporous outer one. The latter samples exhibit a significantly reduced photocurrent response at short wavelengths and an essentially higher concentration of ionised donors as compared with the films obtained by the pulsed discharge method. (C) 2012 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0013-4686
year published 2012
volume 76
beginning page 453
ending page 461
digital object identifier (doi) 10.1016/j.electacta.2012.05.064
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000306621200060
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 5.116
5 year journal impact factor 4.857
category normalized journal impact factor percentile 83.929
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg