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Title: Electrochemical characterization of p-type semiconducting tungsten disulfide photocathodes: efficient photoreduction processes at semiconductor/liquid electrolyte interfaces

Abstract

Single-crystal p-type WS/sub 2/(E/sub g/ approx. = 1.3 eV) has been synthesized and characterized as an electrode material in CH/sub 3/CN/0.1 M (n-Bu/sub 4/N)ClO/sub 4/ and in aqueous electrolytes containing a variety of one-electron redox reagents having different E/sub 1/2/ values. In either CH/sub 3/CN or H/sub 2/O solvent the flat-band potential, E/sub FB/, is measured to be approx. + 0.95 vs SCE. In aqueous I/sub 3//sup -//I/sup -/ the E/sub FB/ is shifted more negatively by at least 0.3 V as is found for n-type WS/sub 2/ photoanodes. Capacitance measurements of the WS/sub 2//electrolyte interface to determine E/sub FB/ accord well with electrochemical measurements. For E/sub 1/2/ more negative than E/sub FB/ the p-type WS/sub 2/ behaves as a photocathode giving an open-circuit photovoltage, E/sub v/(oc), up to approx. 0.8 V depending on E/sub 1/2/. For E/sub 1/2/ between +1.3 and -0.1 V vs SCE, E/sub v/(oc) varies as expected: for E/sub 1/2/ more positive than E/sub FB/ the p-type WS/sub 2/ behaves as a metallic electrode while for E/sub 1/2/ more negative than E/sub FB/ we find E/sub v/(oc) approx. = vertical bar E/sub 1/2/ - E/sub FB/ vertical bar. It appears that for negative redox couples carriermore » inversion results at the p-WS/sub 2/ surface, but for E/sub 1/2/ more negative than -0.1 V vs SCE E/sub v/(oc) declines, a result associated with junction breakdown at sufficiently negative potentials. p-Type WS/sub 2/-based photoelectrochemical cells can be used to effect the sustained conversion of visible light (632.8 nm) to electricity in H/sub 2/O or CH/sub 3/CN with efficiencies of up to approx. 7%. In H/sub 2/O the photochemical reduction to H/sub 2/ can be effected by illumination of p-type WS/sub 2/ modified by depositing approx. 10/sup -7/ mol/cm/sup 2/ of Pd(0) or Pt(0) onto the surface as an H/sub 2/ evolution catalyst. Efficiency for H/sub 2/ evolution from 6 M H/sub 2/SO/sub 4/ is typically 6 to 7% for 632.8 nm (50 mW/cm/sup 2/) intensity.« less

Authors:
; ; ; ; ; ;
Publication Date:
OSTI Identifier:
5718371
Resource Type:
Journal Article
Journal Name:
J. Am. Chem. Soc.; (United States)
Additional Journal Information:
Journal Volume: 105:8
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 08 HYDROGEN; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HYDROGEN PRODUCTION; PHOTOCHEMICAL REACTIONS; SOLAR ENERGY CONVERSION; TUNGSTEN SULFIDES; ELECTROCHEMISTRY; AQUEOUS SOLUTIONS; CATALYSTS; COMPARATIVE EVALUATIONS; EFFICIENCY; FERMI LEVEL; MONOCRYSTALS; NONAQUEOUS SOLVENTS; P-TYPE CONDUCTORS; PALLADIUM; PHOTOCATHODES; PHOTOELECTROCHEMICAL CELLS; PLATINUM; REDOX POTENTIAL; VISIBLE RADIATION; VOLTAMETRY; CATHODES; CHALCOGENIDES; CHEMICAL REACTIONS; CHEMISTRY; CONVERSION; CRYSTALS; DISPERSIONS; ELECTROCHEMICAL CELLS; ELECTRODES; ELECTROMAGNETIC RADIATION; ELEMENTS; ENERGY CONVERSION; ENERGY LEVELS; EQUIPMENT; MATERIALS; METALS; MIXTURES; PLATINUM METALS; RADIATIONS; SEMICONDUCTOR MATERIALS; SOLAR EQUIPMENT; SOLUTIONS; SOLVENTS; SULFIDES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; TUNGSTEN COMPOUNDS; 140505* - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-); 080106 - Hydrogen- Production- Biosynthesis & Photochemical Processes; 400500 - Photochemistry; 400400 - Electrochemistry

Citation Formats

Bagilo, J A, Calabrese, G S, Harrison, D J, Kamieniecki, E, Ricco, A J, Wrighton, M S, and Zoski, G D. Electrochemical characterization of p-type semiconducting tungsten disulfide photocathodes: efficient photoreduction processes at semiconductor/liquid electrolyte interfaces. United States: N. p., 1983. Web. doi:10.1021/ja00346a024.
Bagilo, J A, Calabrese, G S, Harrison, D J, Kamieniecki, E, Ricco, A J, Wrighton, M S, & Zoski, G D. Electrochemical characterization of p-type semiconducting tungsten disulfide photocathodes: efficient photoreduction processes at semiconductor/liquid electrolyte interfaces. United States. https://doi.org/10.1021/ja00346a024
Bagilo, J A, Calabrese, G S, Harrison, D J, Kamieniecki, E, Ricco, A J, Wrighton, M S, and Zoski, G D. Wed . "Electrochemical characterization of p-type semiconducting tungsten disulfide photocathodes: efficient photoreduction processes at semiconductor/liquid electrolyte interfaces". United States. https://doi.org/10.1021/ja00346a024.
@article{osti_5718371,
title = {Electrochemical characterization of p-type semiconducting tungsten disulfide photocathodes: efficient photoreduction processes at semiconductor/liquid electrolyte interfaces},
author = {Bagilo, J A and Calabrese, G S and Harrison, D J and Kamieniecki, E and Ricco, A J and Wrighton, M S and Zoski, G D},
abstractNote = {Single-crystal p-type WS/sub 2/(E/sub g/ approx. = 1.3 eV) has been synthesized and characterized as an electrode material in CH/sub 3/CN/0.1 M (n-Bu/sub 4/N)ClO/sub 4/ and in aqueous electrolytes containing a variety of one-electron redox reagents having different E/sub 1/2/ values. In either CH/sub 3/CN or H/sub 2/O solvent the flat-band potential, E/sub FB/, is measured to be approx. + 0.95 vs SCE. In aqueous I/sub 3//sup -//I/sup -/ the E/sub FB/ is shifted more negatively by at least 0.3 V as is found for n-type WS/sub 2/ photoanodes. Capacitance measurements of the WS/sub 2//electrolyte interface to determine E/sub FB/ accord well with electrochemical measurements. For E/sub 1/2/ more negative than E/sub FB/ the p-type WS/sub 2/ behaves as a photocathode giving an open-circuit photovoltage, E/sub v/(oc), up to approx. 0.8 V depending on E/sub 1/2/. For E/sub 1/2/ between +1.3 and -0.1 V vs SCE, E/sub v/(oc) varies as expected: for E/sub 1/2/ more positive than E/sub FB/ the p-type WS/sub 2/ behaves as a metallic electrode while for E/sub 1/2/ more negative than E/sub FB/ we find E/sub v/(oc) approx. = vertical bar E/sub 1/2/ - E/sub FB/ vertical bar. It appears that for negative redox couples carrier inversion results at the p-WS/sub 2/ surface, but for E/sub 1/2/ more negative than -0.1 V vs SCE E/sub v/(oc) declines, a result associated with junction breakdown at sufficiently negative potentials. p-Type WS/sub 2/-based photoelectrochemical cells can be used to effect the sustained conversion of visible light (632.8 nm) to electricity in H/sub 2/O or CH/sub 3/CN with efficiencies of up to approx. 7%. In H/sub 2/O the photochemical reduction to H/sub 2/ can be effected by illumination of p-type WS/sub 2/ modified by depositing approx. 10/sup -7/ mol/cm/sup 2/ of Pd(0) or Pt(0) onto the surface as an H/sub 2/ evolution catalyst. Efficiency for H/sub 2/ evolution from 6 M H/sub 2/SO/sub 4/ is typically 6 to 7% for 632.8 nm (50 mW/cm/sup 2/) intensity.},
doi = {10.1021/ja00346a024},
url = {https://www.osti.gov/biblio/5718371}, journal = {J. Am. Chem. Soc.; (United States)},
number = ,
volume = 105:8,
place = {United States},
year = {1983},
month = {4}
}