PHOTO-ELECTROCHEMICAL QUANTUM EFFICIENCY OF TiO2 THIN FILMS : EFFECT OF CRISTAL STRUCTURE, PLASMA HYDROGENATION AND SURFACE PHOTOETCHING

Teyar E; Chari A

Article Details

PHOTO-ELECTROCHEMICAL QUANTUM EFFICIENCY OF TiO2 THIN FILMS : EFFECT OF CRISTAL STRUCTURE, PLASMA HYDROGENATION AND SURFACE PHOTOETCHING

Authors:

Teyar E | Chari A

Publisher:

Université Mentouri de Constantine

Journal:

Sciences & technologie. A, sciences exactes Issue 26, pp.73-86

Document Type:

Article

Publication Date:

12/2007

Document Language:

English

Document ID (Org No.):

2001909425

pISSN:

2602-7739

Keywords:

Abstract:

 The use of semi-conducting materials in the photoelectrochemical detoxification of water became a very important
research field. For this purpose, TiO2 nanostructures thin films with size of 18 nm to 45nm have been synthesized at low
temperature. It is found by means of cyclic voltametry and coulometry measurements that the best photoelectrochemical
quantum efficiency under UV monochromatic light with a wavelength of 365 nm and a solution of NaOH 0.1N is obtained in
the case of thermal oxidation deposition method which can reach 28% compared to ultrasonic spray and dip coating methods
of which the quantum is less than 20%. The crystal structure has an influence on the photo-degradation of methanol. The crystal
structure which is recommended for this task is the anatase one, especially in the dipping case when the quantum increases after
addition of methanol more than twice compared to the solution of NaOH without methanol. The photoelectrochemical quantum
efficiency of these films is related to the number of dips and annealing under air at 550°C during one hour. The annealing has
no effect on the quantum efficiency of the films, but decreases there photocatalytic activity as showed by the measure of the
photocurrent related to methanol photodegradation. The annealing has no effect on the crystal structure of the material. The
impedance spectroscopy of six dips deposited films with and without methanol shows that the annealing increases the doping
and weakly decreases the film quantum efficiency. This implies, the importance of surface morphology which the rough is
decreasing as showed by scanning electron microscopy. The effect of the precursor concentration in ethanol have been
investigated by using films, synthesized at T=550°C. The quantum efficiency increases weakly according the precursor
concentration. It tends towards a saturation at great concentrations of precursor. In Na OH with methanol added, it passes by a
maximum at a proportion 1 to 9. The cyclic voltametry and the impedance spectroscopy showed that the incorporation of
hydrogen by plasma in TiO2 films decreases photoelectrochemical quantum efficiency in NaOH electrolyte and increases the
doping concentration. The photoelectrochemical quantum efficiency in NaOH electrolyte of photoetched films in H2SO4 at full
UV light increased two times greater than of non photoetched one (26.7% versus 14%).

Article Details

PHOTO-ELECTROCHEMICAL QUANTUM EFFICIENCY OF TiO2 THIN FILMS : EFFECT OF CRISTAL STRUCTURE, PLASMA HYDROGENATION AND SURFACE PHOTOETCHING

Authors:

Teyar E | Chari A

Publisher:

Université Mentouri de Constantine

Journal:

Sciences & technologie. A, sciences exactes Issue 26, pp.73-86

Document Type:

Article

Publication Date:

12/2007

Document Language:

English

Document ID (Org No.):

2001909425

pISSN:

2602-7739

crystal structure

hydrogenation

photoetching

photoelectrochemical quantum efficiency

Issues

Article Details

PHOTO-ELECTROCHEMICAL QUANTUM EFFICIENCY OF TiO2 THIN FILMS : EFFECT OF CRISTAL STRUCTURE, PLASMA HYDROGENATION AND SURFACE PHOTOETCHING

Authors: Teyar E | Chari A

Publisher: Université Mentouri de Constantine

Journal: Sciences & technologie. A, sciences exactes Issue 26, pp.73-86

Document Type: Article

Publication Date: 12/2007

Document Language: English

Document ID (Org No.): 2001909425

pISSN: 2602-7739

crystal structure

hydrogenation

photoetching

photoelectrochemical quantum efficiency

Issues

Authors:

Teyar E | Chari A

Publisher:

Université Mentouri de Constantine

Journal:

Sciences & technologie. A, sciences exactes Issue 26, pp.73-86

Document Type:

Article

Publication Date:

12/2007

Document Language:

English

Document ID (Org No.):

2001909425

pISSN:

2602-7739