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2013 | Buch

Photoelectrochemical Water Splitting

Standards, Experimental Methods, and Protocols

verfasst von: Zhebo Chen, Huyen N. Dinh, Eric Miller

Verlag: Springer New York

Buchreihe : SpringerBriefs in Energy

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This book outlines many of the techniques involved in materials development and characterization for photoelectrochemical (PEC) – for example, proper metrics for describing material performance, how to assemble testing cells and prepare materials for assessment of their properties, and how to perform the experimental measurements needed to achieve reliable results towards better scientific understanding. For each technique, proper procedure, benefits, limitations, and data interpretation are discussed. Consolidating this information in a short, accessible, and easy to read reference guide will allow researchers to more rapidly immerse themselves into PEC research and also better compare their results against those of other researchers to better advance materials development. This book serves as a “how-to” guide for researchers engaged in or interested in engaging in the field of photoelectrochemical (PEC) water splitting. PEC water splitting is a rapidly growing field of research in which the goal is to develop materials which can absorb the energy from sunlight to drive electrochemical hydrogen production from the splitting of water. The substantial complexity in the scientific understanding and experimental protocols needed to sufficiently pursue accurate and reliable materials development means that a large need exists to consolidate and standardize the most common methods utilized by researchers in this field.

Inhaltsverzeichnis

Frontmatter
Chapter 1. Introduction
Abstract
Solar photoelectrochemical (PEC) hydrogen production is one of the promising technologies that could potentially provide a clean, cost-effective, and domestically produced energy carrier by taking advantage of the *120,000 TW of radiation that continually strikes the earth’s surface. To date, no cost-effective materials system satisfies all of the technical requirements listed above for practical hydrogen production. Despite the challenges, there are promising pathways for achieving the important goal of efficient, cost-effective PEC hydrogen production. For continued progress in overcoming the most important remaining scientific and engineering barriers, widely accepted standards in the characterization and reporting of PEC materials and devices are needed.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 2. Efficiency Definitions in the Field of PEC
Abstract
Overall solar-to-hydrogen (STH) efficiency is the most important parameter to characterize a PEC device. In fact, materials systems themselves are effectively defined by their highest-recorded STH efficiency; it is the single value by which all PEC devices can be reliably ranked against one another [1]. Unfortunately, published literature in the area of PEC sometimes contains confusing information regarding efficiency including invalid mathematical expressions for device efficiency, improper experimental methods for obtaining efficiency values, and/or wide-scale reporting of efficiencies other than STH without clear distinction. The first goal of this document is to establish proper definitions and mathematical expressions for device efficiencies. Among these definitions, we identify those that are acceptable for wide-scale benchmarking and reporting (for instance in the form of press releases to mainstream media) as well as those definitions which are helpful for their scientific value in material characterization and diagnostic testing (and suitable for journal publications). Later in this document, we overview the proper experimental procedures as well as common pitfalls that concern each type of efficiency measurement.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 3. Experimental Considerations
Abstract
Standardized characterization of PEC materials and photoelectrodes requires careful attention to experimental methods in sample preparation and testing setups. Fundamental experimental considerations are discussed in this chapter.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 4. PEC Characterization Flowchart
Abstract
The goal of PEC materials development is to design a material system that has the potential to satisfy most, if not all, of the requirements for cost-effective PEC hydrogen production. Figure 1 presents a recommended flowchart for the characterization of candidate PEC materials. The key knowledge gained as well as limitations of the different characterization techniques, highlighted in Table 1, are described in detail in following sections of this document. A material that can survive the rigorous testing set forth in this flowchart will be a particularly promising candidate for incorporation into an industrially deployable device for PEC hydrogen production. This organized approach to PEC characterization is intended to streamline the process for material screening so that discovery of promising candidates occurs at a faster and more orderly pace.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 5. UV-Vis Spectroscopy
Abstract
In a UV-Vis (ultraviolet-visible light) spectroscopic measurement, light absorption as a function of wavelength provides information about electronic transitions occurring in the material. For semiconductors, UV-Vis spectroscopy offers a convenient method of estimating the optical band gap, since it probes electronic transitions between the valence band and the conduction band. Transmission UV-Vis, Diffuse Reflectance UV-Vis, and Absorption UV-Vis configurations are discussed.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 6. Flat-Band Potential Techniques
Abstract
It is important to determine the conductivity and flat-band potential (Efb) of a photoelectrode before carrying out any photoelectrochemical experiments. These properties help to elucidate the band structure of a semiconductor which ultimately determines its ability to drive efficient water splitting. The three different techniques that can estimate the Efb are: Illuminated OCP, Mott–Schottky and Photocurrent Onset. The Efb should be independent of the technique used to determine it. Due to the inherent shortcomings of each technique, there is often a lack of agreement of the values determined by the various analyses. Researchers should be aware of these limitations in interpreting results.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 7. Incident Photon-to-Current Efficiency and Photocurrent Spectroscopy
Abstract
The incident photon-to-current efficiency (IPCE) is a measure of the ratio of the photocurrent (converted to an electron transfer rate) versus the rate of incident photons (converted from the calibrated power of a light source) as a function of wavelength. Measuring the IPCE is also useful to determine the band gap. The band gap derived from IPCE may be higher than that obtained by optical spectroscopy techniques. Applied bias IPCE and white light bias IPCE experiments are discussed. Photocurrent spectroscopy examines the photocurrent produced by an electrochemical cell as a function of wavelength of the incident light. The optical bulk band gap of the semiconductor electrode can be determined along with information about whether it is a direct or indirect transition.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 8. 2-Electrode Short Circuit and j–V
Abstract
Solar-to-hydrogen (STH) conversion efficiency is the most important figure of merit to gage the potential of a semiconductor material to photoelectrochemically split water (see Chapter “Efficiency Definitions in the Field of PEC”). It is projected that STH conversion efficiencies in excess of 10 % will be needed for practical hydrogen production systems [1]. Taken in conjunction with gas detection measurements (see Chapter “Stability Testing”), the photocurrent density (j SC) under short-circuited conditions (i.e., zero applied bias) in a 2-electrode measurement is critical in determining the STH conversion efficiency. Moreover, applied bias experiments using the 2-electrode configuration can shed important light on the water splitting capabilities and limits of a PEC material system.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 9. Hydrogen and Oxygen Detection from Photoelectrodes
Abstract
The chemical products of PEC water splitting processes are the evolved hydrogen and oxygen gases. Standard experimental methods for detecting and validating the quantity and quality of the product gases are critical. Faradaic efficiencies for the water splitting reaction in the given system can be determined. Three examples of PEC reactors are discussed, including batch, flow, and recirculating batch reactor.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Chapter 10. Stability Testing
Abstract
Photocorrosion in aqueous environments is one of the most significant obstacles to the widespread deployment of semiconductor materials as PEC devices for solar hydrogen production. The photogenerated holes and electrons in semiconductor electrodes are generally characterized by strong oxidizing and reducing potentials, respectively. Instead of driving the OER or HER, these holes and electrons may oxidize or reduce the semiconductor itself, causing undesired physical and chemical changes.
Zhebo Chen, Todd G. Deutsch, Huyen N. Dinh, Kazunari Domen, Keith Emery, Arnold J. Forman, Nicolas Gaillard, Roxanne Garland, Clemens Heske, Thomas F. Jaramillo, Alan Kleiman-Shwarsctein, Eric Miller, Kazuhiro Takanabe, John Turner
Backmatter
Metadaten
Titel
Photoelectrochemical Water Splitting
verfasst von
Zhebo Chen
Huyen N. Dinh
Eric Miller
Copyright-Jahr
2013
Verlag
Springer New York
Electronic ISBN
978-1-4614-8298-7
Print ISBN
978-1-4614-8297-0
DOI
https://doi.org/10.1007/978-1-4614-8298-7