Abstract
This chapter presents an overview of several photoelectrochemical characterization techniques and the equipment needed to carry out these measurements. It starts with a detailed description of the photoelectrochemical cell and its components. A few selected cell designs are shown and discussed, and several considerations for choosing suitable photoelectrode substrates, electrolyte solutions, and counter and reference electrodes are given. This is followed by a description of two experimental setups for photocurrent measurements, one for measurements under simulated sunlight and one for wavelength-dependent (monochromatic) measurements. The components of these setups are described, with special emphasis given to the inner workings of the potentiostat and the various types and specifications of solar simulators. The information that can be obtained from photocurrent measurements, such as photocurrent onset potentials, performance limiting factors, and quantum efficiencies is described next. The final section reviews the principles, equipment, and practical considerations for Mott–Schottky measurements. Common pitfalls of impedance measurements are outlined, and several strategies and precautions to avoid or minimize measurement errors are given.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
Examples of optimization parameters for photoelectrode synthesis are deposition temperature, substrate cleaning method, additives used to optimize the boiling point, surface tension, water content or viscosity of a solution, postdeposition heat treatments to improve the crystallinity, dipping as-prepared samples in a precursor solution to improve interparticle contacts, etc.
- 2.
Most photoelectrochemical cells used in PEC research are designed to study the properties of a single photoelectrode. PEC cells in which more than one electrode is illuminated at once (e.g., tandem cells) are somewhat more complicated and will not be considered here.
- 3.
Except for a small dip around ~1400 nm, depending on the purity grade.
- 4.
A 50 mm, 3 mm thick window of UV-grade fused silica costs ~40 EUR (in 2010). Note that fused silica is often incorrectly referred to as “quartz,” which is the crystalline form of SiO2 that shows slightly better transmission than fused silica at a much higher price.
- 5.
Factors that may contribute to the total overpotential include slow charge transfer across the Helmholtz layer, slow reaction kinetics due to preceding or subsequent reaction steps, mass transport limitations (diffusion, convection, migration), and removal of the solvation sheet of water molecules (dipoles) surrounding each ion.
- 6.
Each ion is surrounded by a solvation sheath of water molecules (see Sect. 2.6.2). The size and charge of the central ion determine the configuration of the surrounding molecules, and this in turn determines the interaction strength of the ion with neighboring ions in the solution.
- 7.
- 8.
The modulation input is used for, e.g., impedance measurements, which will be discussed later.
- 9.
Most proprietary software packages include support for several types of frequency response analyzers, sometimes even for models made by other manufacturers.
- 10.
The AM1.5D spectrum only contains the direct contributions over a 5° field of view, and has an integrated intensity of 768 W/m2.
- 11.
In exceptional cases, ignition of a high-power gas discharge lamp can even destroy electronic equipment. This has happened once in the author’s laboratory to a Solartron 1286 potentiostat after switching on an older type 450 W Xe lamp.
- 12.
Monochromators have both entrance and exit slits. It is recommended to use the same width for both slits.
- 13.
The situation is a bit complicated in a three-electrode system since the potential of the counter electrode is not known. One can argue that for a counter-electrode with a low overpotential for H2 evolution, the potential of the counter electrode should be close to that of the reversible hydrogen potential – provided that the concentration of dissolved hydrogen is high enough. This can be easily verified by a separate measurement of V WE –V CE during a three-electrode linear sweep voltammogram. One particular test in the author’s laboratory showed that at a current density >0.5 mA/cm2, the potential of a coiled Pt wire electrode approached that of the reversible hydrogen electrode to within ~0.1 V. At lower current densities, however, deviations as large as 1 V were observed.
- 14.
In contrast to photocurrent measurements, discontinuities in the ICPE spectrum can be easily avoided by using the same combination of wavelength range and long pass filters while measuring the light intensity with the calibrated photodiode.
- 15.
There are several other, more complicated elements available to describe the various processes that can occur in a photoelectrochemical cell, such as the Warburg element (to model diffusion), the Constant Phase Element (CPE, used to describe processes that have a distribution of time constants or activation energies), and transmission lines (to model porous electrodes [47]). Porous electrodes and CPE elements that represent nonideal capacitive elements are briefly discussed below. For more detailed information, the reader is referred to the literature [48, 49].
- 16.
Preconditioning steps are, e.g., removal of the dc component of the signal by passing it through a high pass filter (a capacitor), or amplification/attenuation of the signal by a certain fixed factor. These steps are often necessary to ensure that the signal falls within the range that the FRA can handle internally. These steps do not (and should not) influence the final measurement results.
- 17.
When writing one’s own measurement software, it should be realized that the FRA simply divides the voltage signals at both input channels – it does not know what these signals represent. Since the (voltage) signal that represents the current is given by I monitor × R i (Fig. 3.6), the FRA reports the impedance as V/(I × R i) – it does not “know” the value of the range resistor R i. The software should therefore multiply the reported value by R i to obtain the actual impedance.
- 18.
The value of kT/e at room temperature is ~25 mV.
- 19.
This membrane forms the junction between the internal solution of the reference electrode and the electrolyte of the PEC cell.
- 20.
The donors/acceptors are then no longer shallow, but deep.
- 21.
Note that a semicircle in the Z′ vs. Z″ (Nyquist) plot is only observed in the presence of a resistive element in parallel to the space charge capacitance.
- 22.
CPE elements are usually indicated by the letter Q, analogous to the letters R and C used for resistive and capacitive elements, respectively.
- 23.
A bulk or surface state with a single, discrete energy level is probably better described by a single additional RC component instead of a CPE element.
References
Chen, Z.B., Jaramillo, T.F., Deutsch, T.G., Kleiman-Shwarsctein, A., Forman, A.J., Gaillard, N., Garland, R., Takanabe, K., Heske, C., Sunkara, M., McFarland, E.W., Domen, K., Miller, E.L., Turner, J.A., Dinh, H.N.: Accelerating materials development for photoelectrochemical hydrogen production: Standards for methods, definitions, and reporting protocols. J. Mater. Res. 25, 3–16 (2010)
Gordon, R.G.: Criteria for choosing transparent conductors. MRS Bull. 25, 52–57 (2000)
Sze, S.M.: Physics of Semiconductor Devices. Wiley, New York (1981)
De Jongh, P.E., Vanmaekelbergh, D., Kelly, J.J.: Photoelectrochemistry of electrodeposited Cu2O. J. Electrochem. Soc. 147, 486–489 (2000)
Minami, T.: New n-type transparent conducting oxides. MRS Bull. 25, 38–44 (2000)
Ferekides, C.S., Mamazza, R., Balasubramanian, U., Morel, D.L.: Transparent conductors and buffer layers for CdTe solar cells. Thin Solid Films 480, 224–229 (2005)
Fortunato, E., Ginley, D., Hosono, H., Paine, D.C.: Transparent conducting oxides for photovoltaics. MRS Bull. 32, 242–247 (2007)
Minami, T., Miyata, T., Yamamoto, T.: Stability of transparent conducting oxide films for use at high temperatures. J. Vac. Sci. Technol. A 17, 1822–1826 (1999)
Abe, R., Higashi, M., Domen, K.: Facile fabrication of an efficient oxynitride TaON photoanode for overall water splitting into H2 and O2 under visible light irradiation. J. Am. Chem. Soc. 132, 11828–11829 (2010)
Goto, K., Kawashima, T., Tanabe, N.: Heat-resisting TCO films for PV cells. Solar Energy Mater. Solar Cells 90, 3251–3260 (2006)
Radiometer Analytical. http://www.radiometer-analytical.com/. Accessed 29 Aug 2011
Sawyer, D.T., Sobkowiak, A., Roberts, J.L.: Electrochemistry for Chemists. Wiley-Interscience, New York (2010)
Rodgers, B.: Research Solutions & Resources LLC. http://www.consultrsr.com/resources/ref/index.htm. Accessed 28 Dec 2010
Compton, R.G., Sanders, G.H.W.: Electrode Potentials. Oxford University Press, Oxford (1996)
Compton, R.G., Banks, C.E.: Understanding Voltammetry. World Scientific Publishing, Oxford (2007)
Hamann, C.H., Hamnett, A., Vielstich, W.: Electrochemistry. Wiley-VCH, Weinheim (2007)
Gilliam, R.J., Graydon, J.W., Kirk, D.W., Thorpe, S.J.: A review of specific conductivities of potassium hydroxide solutions for various concentrations and temperatures. Int. J. Hydrogen Energy 32, 359–364 (2007)
Bertrand, G.L.: Conductivity of ionic solutions. http://web.mst.edu/~gbert/conductivity/cond.html. Accessed 28 Dec 2010
Santato, C., Odziemkowski, M., Ulmann, M., Augustynski, J.: Crystallographically oriented mesoporous WO3 films: synthesis, characterization, and applications. J. Am. Chem. Soc. 123, 10639–10649 (2001)
Alexander, B.D., Kulesza, P.J., Rutkowska, L., Solarska, R., Augustynski, J.: Metal oxide photoanodes for solar hydrogen production. J. Mater. Chem. 18, 2298–2303 (2008)
Kay, A., Cesar, I., Grätzel, M.: New benchmark for water photooxidation by nanostructured alpha-Fe2O3 films. J. Am. Chem. Soc. 128, 15714–15721 (2006)
Sayama, K., Nomura, A., Arai, T., Sugita, T., Abe, R., Yanagida, M., Oi, T., Iwasaki, Y., Abe, Y., Sugihara, H.: Photoelectrochemical decomposition of water into H2 and O2 on porous BiVO4 thin-film electrodes under visible light and significant effect of Ag ion treatment. J. Phys. Chem. B 110, 11352–11360 (2006)
Horowitz, P., Hill, W.: The Art of Electronics. Cambridge University Press, Cambridge (1989)
Solar Irradiance Data, ASTM-G173-03 (AM1.5, global tilt): http://rredc.nrel.gov/solar/spectra/am1.5/. Accessed 11 Aug 2010
Murphy, A.B., Barnes, P.R.F., Randeniya, L.K., Plumb, I.C., Grey, I.E., Horne, M.D., Glasscock, J.A.: Efficiency of solar water splitting using semiconductor electrodes. Int. J. Hydrogen Energy 31, 1999–2017 (2006)
Jenkins, F.A., White, H.E.: Fundamentals of Optics. McGraw-Hill, New York (1981)
Hobbs, P.C.D.: Building Electro-Optical Systems – Making It All Work. Wiley, New York (2000)
Hecht, E.: Optics. Addison-Wesley, Reading (2001)
Lerner, J.M., Thevenon, A.: Optics Tutorial. http://www.horiba.com/scientific/products/optics-tutorial/. Accessed 10 Jan 2011
Oriel Monochromators: http://www.newport.com/. Accessed 10 Jan 2011
Acton Research Monochromators: http://www.princetoninstruments.com/. Accessed 29 Aug 2011
Schott Optical Filters: http://www.schott.com/advanced_optics/english/filter/index.html. Accessed 10 Jan 2011
Liang, Y.Q., Enache, C.S., van de Krol, R.: Photoelectrochemical characterization of sprayed alpha-Fe2O3 thin films: influence of Si doping and SnO2 interfacial layer. Int. J. Photoenergy (2008). doi:10.1155/2008/739864
Kennedy, J.H., Frese Jr., K.W.: Flatband potentials and donor densities of polycrystalline alpha-Fe2O3 determined from Mott–Schottky plots. J. Electrochem. Soc. 125, 723–726 (1978)
Sanchez, C., Hendewerk, M., Sieber, K.D., Somorjai, G.A.: Synthesis, bulk, and surface characterization of niobium-doped Fe2O3 single crystals. J. Solid State Chem. 61, 47–55 (1986)
Tilley, S.D., Cornuz, M., Sivula, K., Gratzel, M.: Light-induced water splitting with hematite: improved nanostructure and iridium oxide catalysis. Angew. Chem. Int. Ed. 49, 6405–6408 (2010)
Grätzel, M.: Photoelectrochemical cells. Nature 414, 338–344 (2001)
Grätzel, M.: Mesoscopic solar cells for electricity and hydrogen production from sunlight. Chem. Lett. 34, 8–13 (2005)
Brillet, J., Cornuz, M., Le Formal, F., Yum, J.H., Grätzel, M., Sivula, K.: Examining architectures of photoanode-photovoltaic tandem cells for solar water splitting. J. Mater. Res. 25, 17–24 (2010)
Lindquist, S.E., Finnstrom, B., Tegner, L.: Photoelectrochemical properties of polycrystalline TiO2 thin film electrodes on quartz substrates. J. Electrochem. Soc. 130, 351–358 (1983)
Inoue, Y., Asai, Y., Sato, K.: Photocatalysts with tunnel structures for decomposition of water. 1. BaTi4O9, a pentagonal prism tunnel structure, and its combination with various promoters. J. Chem. Soc. Faraday Trans. 90, 797–802 (1994)
Sato, J., Saito, N., Yamada, Y., Maeda, K., Takata, T., Kondo, J.N., Hara, M., Kobayashi, H., Domen, K., Inoue, Y.: RuO2-loaded beta-Ge3N4 as a non-oxide photocatalyst for overall water splitting. J. Am. Chem. Soc. 127, 4150–4151 (2005)
Kanan, M.W., Nocera, D.G.: In situ formation of an oxygen-evolving catalyst in neutral water containing phosphate and Co2+. Science 321, 1072–1075 (2008)
Peter, L.M., Li, J., Peat, R.: Surface recombination at semiconductor electrodes. 1. Transient and steady-state photocurrents. J. Electroanal. Chem. 165, 29–40 (1984)
Salvador, P., Gutierrez, C.: Analysis of the transient photocurrent time behavior of a sintered n-SrTiO3 electrode in water photoelectrolysis. J. Electroanal. Chem. 160, 117–130 (1984)
Abdi, F.F., van de Krol, R.: Efficient cobalt phosphate-catalyzed BiVO4 photoanodes for photoelectrochemical water splitting (Submitted)
Bisquert, J., Garcia-Belmonte, G., Fabregat-Santiago, F., Ferriols, N.S., Bogdanoff, P., Pereira, E.C.: Doubling exponent models for the analysis of porous film electrodes by impedance. Relaxation of TiO2 nanoporous in aqueous solution. J. Phys. Chem. B 104, 2287–2298 (2000)
MacDonald, J.R.: Impedance Spectroscopy: Emphasizing Solid Materials and Systems. Wiley-Interscience, New York (1987)
Orazem, M., Tribollet, B.: Electrochemical Impedance Spectroscopy. Wiley-Interscience, New York (2008)
Van de Krol, R., Goossens, A., Schoonman, J.: Mott–Schottky analysis of nanometer-scale thin-film anatase TiO2. J. Electrochem. Soc. 144, 1723–1727 (1997)
Van de Krol, R., Goossens, A., Schoonman, J.: Mott–Schottky analysis of nanometer-scale thin-film anatase TiO2 (Erratum vol. 144, pg 1723, 1997). J. Electrochem. Soc. 145, 3697–3697 (1998)
Gomes, W.P., Cardon, F.: Electron-energy levels in semiconductor electrochemistry. Prog. Surf. Sci. 12, 155–215 (1982)
Morrison, S.R.: Electrochemistry of Semiconductor and Oxidized Metal Electrodes. Plenum, New York (1980)
Goossens, A., Schoonman, J.: The impedance of surface recombination at illuminated semiconductor electrodes – a nonequilibrium approach. J. Electroanal. Chem. 289, 11–27 (1990)
Enache, C.S., Lloyd, D., Damen, M.R., Schoonman, J., Van de Krol, R.: Photo-electrochemical properties of thin-film InVO4 photoanodes: the role of deep donor states. J. Phys. Chem. C 113, 19351–19360 (2009)
Bisquert, J., Grätzel, M., Wang, Q., Fabregat-Santiago, F.: Three-channel transmission line impedance model for mesoscopic oxide electrodes functionalized with a conductive coating. J. Phys. Chem. B 110, 11284–11290 (2006)
Cesar, I., Sivula, K., Kay, A., Zboril, R., Grätzel, M.: Influence of feature size, film thickness, and silicon doping on the performance of nanostructured hematite photoanodes for solar water splitting. J. Phys. Chem. C 113, 772–782 (2009)
Schoonman, J., Vos, K., Blasse, G.: Donor densities in TiO2 photoelectrodes. J. Electrochem. Soc. 128, 1154–1157 (1981)
Hsu, C.H., Mansfeld, F.: Technical note: concerning the conversion of the constant phase element parameter Y0 into a capacitance. Corrosion 57, 747–748 (2001)
Dutoit, E.C., VanMeirhaeghe, R.L., Cardon, F., Gomes, W.P.: Investigation on frequency-dependence of impedance of nearly ideally polarizable semiconductor electrodes CdSe, CdS and TiO2. Ber. Bunsenges. Phys. Chem. 79, 1206–1213 (1975)
Oskam, G., Vanmaekelbergh, D., Kelly, J.J.: A reappraisal of the frequency-dependence of the impedance of semiconductor electrodes. J. Electroanal. Chem. 315, 65–85 (1991)
Acknowledgments
The author gratefully acknowledges the NWO-ACTS Sustainable Hydrogen program (project 053.61.009) and the European Commission’s Framework 7 program (NanoPEC, Project 227179) for support.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2012 Springer Science+Business Media, LLC
About this chapter
Cite this chapter
van de Krol, R. (2012). Photoelectrochemical Measurements. In: van de Krol, R., Grätzel, M. (eds) Photoelectrochemical Hydrogen Production. Electronic Materials: Science & Technology, vol 102. Springer, Boston, MA. https://doi.org/10.1007/978-1-4614-1380-6_3
Download citation
DOI: https://doi.org/10.1007/978-1-4614-1380-6_3
Published:
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4614-1379-0
Online ISBN: 978-1-4614-1380-6
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)