Preparation and photoelectrochemical characterization of porphyrin-sensitized ? -Fe2 O3 thin films
Keywords: iron, adsorption, films, electron, corrosion, characterization, state, porphyrins, minerals, impedance, ray, microscopy, surface, potassium, light, oxide, time, electrodeposition, diffraction, layer, carrier, thin, precursor, force, analysis, ores, iodide, measurements, concentration, transient, photocurrent, illumination, hematite, scanning, response, X, Electrochemical, solution, atomic, Semiconducting, Ki, characteristic, Photoelectrochemical, morphological, tetrakis, Mott-Schottky, White-light
Abstract
The photoelectrochemical response of electrodeposited hematite (? -Fe2 O3) thin films, whose surface has been sensitized by the adsorption of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP), was studied. The ? -Fe2 O3 thin films were obtained by the annealing of an electrodeposited ? -FeOOH precursor layer. The structural and morphological characteristics of the resulting hematite films were studied by X-ray diffraction, scanning electron microscopy, and atomic force microscopy techniques. The semiconducting characteristics of unmodified and sensitized TCPP hematite films were determined by electrochemical impedance measurements and by Mott-Schottky analysis. The hematite films exhibited an n-type behavior and a donor carrier concentration (ND =3× 1017 cm-3) for both unmodified and TCPP-sensitized ones. However, it was observed that the presence of TCPP shifts the energy of the surface states to higher values. The photoelectrochemical response of the unmodified and sensitized ? -Fe2 O3 electrodes was followed by means of photovoltammetry and photocurrent-time transient techniques in a 0.1 M NaOHK+0.1 M KI solution under 25 mW/ cm2 white light illumination. The results showed that the photocurrent response exhibited by the TCPP-sensitized hematite films was 70% higher than the unmodified ones. © 2010 The Electrochemical Society.
Más información
Título de la Revista: | JOURNAL OF THE ELECTROCHEMICAL SOCIETY |
Volumen: | 157 |
Número: | 5 |
Editorial: | ELECTROCHEMICAL SOC INC |
Fecha de publicación: | 2010 |
URL: | http://www.scopus.com/inward/record.url?eid=2-s2.0-77951165268&partnerID=q2rCbXpz |