Appropriate strategies for determining the photoconversion efficiency of water photoelectrolysis cells : A review with examples using titania nanotube array photoanodes

Proper determination of light to chemical energy conversion efficiency of a photoelectrochemical cell is critical in evaluating its performance. Since the demonstration of photocatalytic water splitting using semiconductor electrodes, many strategies have been suggested and employed for the determination of photoconversion efficiency. We review these approaches as well as factors limiting ideal case efficiencies. Cell efficiency values are found to vary considerably depending upon the errors involved in the basic assumptions and measurement procedures. With researchers using different expressions for efficiency calculation, the values can be inconsistent and a direct comparison meaningless; we demonstrate this with the help of photocurrent data obtained from a photoelectrolysis cell employing titania nanotube array photoanodes. We find, and demonstrate, that realistic solar photoconversion efficiencies can be estimated with the help of incident photon to electron conversion efficiency (IPCE) values and solar irradiance data using the expression: ratio of the net power output to the power supplied by the incident light, where the net power output is the difference between the maximum electrical power available from the hydrogen produced and the power supplied by an external source. The power from the external source is determined by taking product of the photocurrent and the potential difference between the working and counter electrodes.

[1]  O. Park,et al.  Photoelectrochemical water splitting at titanium dioxide nanotubes coated with tungsten trioxide , 2006 .

[2]  B. Kasemo,et al.  Comment on "Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2" (II) , 2003, Science.

[3]  J. O'm. Bockris,et al.  Significant Efficiency Increase in Self‐Driven Photoelectrochemical Cell for Water Photoelectrolysis , 1987 .

[4]  A. Nozik,et al.  Photoelectrolysis of water using semiconducting TiO2 crystals , 1975, Nature.

[5]  Allen J. Bard,et al.  Electrochemical Methods: Fundamentals and Applications , 1980 .

[6]  D. Ginley,et al.  Principles of photoelectrochemical, solar energy conversion , 1980 .

[7]  H. Strunk,et al.  Texture and electronic activity of grain boundaries in Cu(In,Ga)Se2 thin films , 2006 .

[8]  A. Nozik,et al.  Solar conversion efficiency of photovoltaic and photoelectrolysis cells with carrier multiplication absorbers , 2006 .

[9]  Craig A Grimes,et al.  Enhanced photocleavage of water using titania nanotube arrays. , 2005, Nano letters.

[10]  B. O. Seraphin,et al.  Solar energy conversion : solid-state physics aspects , 1979 .

[11]  J. K. Dohrmann,et al.  Energy conversion by photoelectrolysis of water: Determination of efficiency by in situ photocalorimetry , 1992 .

[12]  R. L. Hulstrom,et al.  Terrestrial solar spectral data sets , 1982 .

[13]  Adam Heller,et al.  Efficient p ‐ InP ( Rh ‐ H alloy ) and p ‐ InP ( Re ‐ H alloy ) Hydrogen Evolving Photocathodes , 1982 .

[14]  Amal K. Ghosh,et al.  Photoelectrolysis of water in sunlight with sensitized semiconductor electrodes , 1977 .

[15]  H. Gerischer.  Solar photoelectrolysis with semiconductor electrodes , 1979 .

[16]  C. Riordan,et al.  Spectral solar irradiance data sets for selected terrestrial conditions , 1985 .

[17]  A. Heller.  Electrochemical solar cells , 1982 .

[18]  V. K. Mahajan,et al.  Determination of photo conversion efficiency of nanotubular titanium oxide photo-electrochemical cell for solar hydrogen generation , 2006 .

[19]  W. Ingler,et al.  Response to Comments on "Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2" , 2003, Science.

[20]  Craig A. Grimes,et al.  Visible light photoelectrochemical and water-photoelectrolysis properties of titania nanotube arrays , 2006 .

[21]  J. Augustynski,et al.  Spectral Photoresponses of Carbon-Doped TiO2 Film Electrodes , 2004 .

[22]  Bruce A. Parkinson,et al.  On the efficiency and stability of photoelectrochemical devices , 1984 .

[23]  Akira Fujishima,et al.  Hydrogen Production under Sunlight with an Electrochemical Photocell , 1975 .

[24]  A. Fujishima,et al.  Electrochemical Photolysis of Water at a Semiconductor Electrode , 1972, Nature.

[25]  James R. Bolton,et al.  Solar photoproduction of hydrogen: A review , 1996 .

[26]  I. E. Grey,et al.  Efficiency of solar water splitting using semiconductor electrodes , 2006 .

[27]  M. Dignam,et al.  Efficiency of Splitting Water with Semiconducting Photoelectrodes , 1984 .

[28]  Adam Heller,et al.  Efficient Solar to Chemical Conversion: 12% Efficient Photoassisted Electrolysis in the [ p -type InP(Ru)]/HCl-KCl/Pt(Rh) Cell , 1981 .

[29]  J. Bolton,et al.  Requirements for ideal performance of photochemical and photovoltaic solar energy converters , 1990 .

[30]  Vladimir M. Aroutiounian,et al.  Metal oxide photoelectrodes for hydrogen generation using solar radiation-driven water splitting , 2005 .

[31]  H. Queisser,et al.  Detailed Balance Limit of Efficiency of p‐n Junction Solar Cells , 1961 .

[32]  W. Ingler,et al.  Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2 , 2002, Science.

[33]  A. Gloskovskii,et al.  Time-of-flight photoelectron spectromicroscopy of single MoS2 nanotubes , 2006 .

[34]  Charles C. Sorrell,et al.  Photo-electrochemical hydrogen generation from water using solar energy. Materials-related aspects , 2002 .

[35]  Mohammad Khaja Nazeeruddin,et al.  Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes , 1993 .

[36]  Arthur J. Nozik,et al.  Photoelectrochemistry: Applications to Solar Energy Conversion , 1978 .

[37]  H. Gerischer.  Heterogeneous electrochemical systems for solar energy conversion , 1980 .

[38]  Shahed U. M. Khan,et al.  PHOTOELECTROCHEMICAL SPLITTING OF WATER AT NANOCRYSTALLINE N-FE2O3 THIN-FILM ELECTRODES , 1999 .

[39]  R. T. Ross,et al.  CHAPTER 11 – PHOTOCHEMICAL ENERGY STORAGE: AN ANALYSIS OF LIMITS , 1981 .

[40]  James R. Bolton,et al.  Limiting and realizable efficiencies of solar photolysis of water , 1985, Nature.

[41]  A. Fujishima,et al.  TiO2 Photocatalysis: A Historical Overview and Future Prospects , 2005 .

[42]  Michael Grätzel,et al.  New Benchmark for Water Photooxidation by Nanostructured α-Fe2O3 Films , 2006 .

[43]  D. Ginley,et al.  Photoassisted electrolysis of water by irradiation of a titanium dioxide electrode. , 1975, Proceedings of the National Academy of Sciences of the United States of America.

[44]  Eric L. Miller,et al.  Photoelectrochemical production of hydrogen : Engineering loss analysis , 1997 .

[45]  D. O. Hall,et al.  Photochemical conversion and storage of solar energy , 1977 .

[46]  Akira Fujishima.  Comment on "Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2" (I) , 2003, Science.

[47]  Craig A Grimes,et al.  Water-photolysis properties of micron-length highly-ordered titania nanotube-arrays. , 2005, Journal of nanoscience and nanotechnology.

[48]  K. Lackner.  Comment on "Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2" (III) , 2003, Science.

[49]  A. Murphy.  Band-gap determination from diffuse reflectance measurements of semiconductor films, and application to photoelectrochemical water-splitting , 2007 .

[50]  Photoelectrolysis of Water with Semiconductor Materials , 1977 .

[51]  Adam Heller.  Conversion of Sunlight into Electrical Power and Photoassisted Electrolysis of Water in Photoelectrochemical Cells , 1981 .