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Title: Photoelectrochemical and impedance characteristics of specular hematite. 1. Photoelectrochemical, parallel conductance, and trap rate studies

Abstract

Most of the samples of naturally occurring specular hematite (Quebec, Canada) containing 0.6 mass % Ti were found to degenerate semiconductors due to oxygen deficiency in these samples and yielded negligible photocurrents (i/sub ph/) in a photoelectrochemical (PEC) cell. When heated in air to 900/degrees/C for 1 h or more after polishing, these samples developed substantial photocurrents as photoanodes in a PEC cell. The PEC, solid-state, and optical properties have been investigated by current-voltage and impedance measurements and by photocurrent spectroscopy. Information has been derived on the trapping centers and surface states with energies within the band-gap region. Inherent bulk states at 1.5 eV optical (approx. 0.5-0.7 eV below the conduction band edge) are responsible for trapping of the majority carriers and for electron-hole recombination and surface states. The trapping and detrapping effects due to surface states could be eliminated and i/sub ph/ greatly enhanced by filling the surface states by pyrogallol adsorption. The deep impurity/donor levels are also responsible for the trapping and recombination effects and consequently the low photon conversion efficiencies. Methods of improving the efficiencies have been suggested.

Authors:
; ;
Publication Date:
Research Org.:
Canada Centre for Mineral and Energy Technology, Ottawa, Ontario
OSTI Identifier:
6220165
Resource Type:
Journal Article
Journal Name:
J. Phys. Chem.; (United States)
Additional Journal Information:
Journal Volume: 92:23
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 08 HYDROGEN; IRON OXIDES; ELECTRIC CONDUCTIVITY; PHOTOCHEMICAL REACTIONS; TITANIUM; EXPERIMENTAL DATA; PHOTOANODES; PHOTOELECTROCHEMICAL CELLS; SEMICONDUCTOR MATERIALS; TRAPPING; ANODES; CHALCOGENIDES; CHEMICAL REACTIONS; DATA; ELECTRICAL PROPERTIES; ELECTROCHEMICAL CELLS; ELECTRODES; ELEMENTS; EQUIPMENT; INFORMATION; IRON COMPOUNDS; MATERIALS; METALS; NUMERICAL DATA; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SOLAR EQUIPMENT; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; 400500* - Photochemistry; 080101 - Hydrogen- Production- Electrolysis; 400400 - Electrochemistry

Citation Formats

Ahmed, S M, Leduc, J, and Haller, S F. Photoelectrochemical and impedance characteristics of specular hematite. 1. Photoelectrochemical, parallel conductance, and trap rate studies. United States: N. p., 1988. Web. doi:10.1021/j100334a033.
Ahmed, S M, Leduc, J, & Haller, S F. Photoelectrochemical and impedance characteristics of specular hematite. 1. Photoelectrochemical, parallel conductance, and trap rate studies. United States. https://doi.org/10.1021/j100334a033
Ahmed, S M, Leduc, J, and Haller, S F. Thu . "Photoelectrochemical and impedance characteristics of specular hematite. 1. Photoelectrochemical, parallel conductance, and trap rate studies". United States. https://doi.org/10.1021/j100334a033.
@article{osti_6220165,
title = {Photoelectrochemical and impedance characteristics of specular hematite. 1. Photoelectrochemical, parallel conductance, and trap rate studies},
author = {Ahmed, S M and Leduc, J and Haller, S F},
abstractNote = {Most of the samples of naturally occurring specular hematite (Quebec, Canada) containing 0.6 mass % Ti were found to degenerate semiconductors due to oxygen deficiency in these samples and yielded negligible photocurrents (i/sub ph/) in a photoelectrochemical (PEC) cell. When heated in air to 900/degrees/C for 1 h or more after polishing, these samples developed substantial photocurrents as photoanodes in a PEC cell. The PEC, solid-state, and optical properties have been investigated by current-voltage and impedance measurements and by photocurrent spectroscopy. Information has been derived on the trapping centers and surface states with energies within the band-gap region. Inherent bulk states at 1.5 eV optical (approx. 0.5-0.7 eV below the conduction band edge) are responsible for trapping of the majority carriers and for electron-hole recombination and surface states. The trapping and detrapping effects due to surface states could be eliminated and i/sub ph/ greatly enhanced by filling the surface states by pyrogallol adsorption. The deep impurity/donor levels are also responsible for the trapping and recombination effects and consequently the low photon conversion efficiencies. Methods of improving the efficiencies have been suggested.},
doi = {10.1021/j100334a033},
url = {https://www.osti.gov/biblio/6220165}, journal = {J. Phys. Chem.; (United States)},
number = ,
volume = 92:23,
place = {United States},
year = {1988},
month = {11}
}