U.S. Department of Energy - Energy Efficiency and Renewable Energy

Fuel Cell Technologies Office

Photoelectrochemical Research Standards and Methods Development

Document Review Request

Help us develop PEC research standards by contributing your review comments on PEC standard testing protocol documents. Please fill out and submit the request to comment form to receive information on how to access the documents.

The Photoelectrochemical (PEC) Working Group has written documents that define appropriate methods and standards for PEC research. The working group invites the PEC international scientific community to submit comments on these documents. Input from a diverse group of researchers will help identify superior PEC research techniques and accelerate their common use.

The working group is publishing documents on standardized techniques and definitions to facilitate meaningful information exchange and material performance comparisons by scientists throughout the world.

Background
Mission and Vision
Standards Working Group Members
Document Descriptions 

Background

In the expanding field of PEC hydrogen production, the standardization of screening methods and reporting has emerged as a necessity. Because of significant technical challenges and limited research and development resources, PEC researchers and funding organizations need quantified, accurate, and consistent characterization results to justify resource priorities.

Additionally, widely accepted standard PEC material characterization protocols will help researchers from different groups to characterize PEC materials and report comparable results. A common understanding of the materials, along with the ability to screen them quickly while guiding research toward the most promising materials, will more efficiently identify materials that meet PEC requirements.

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Mission and Vision of PEC Standards Development

Mission: Create documents that define appropriate methods and standards for photoelectrochemical research and produce a unique benchmark system in which materials can be compared at laboratories with different equipment and setups.

Vision: Develop, with the aid of the international PEC community, clear and concise documents that describe basic methods and standards for photoelectrochemical screening and promote the rapid adoption of these techniques so that PEC materials can be evaluated using common standards and methods.

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Standards Working Group Members

Zhebo Chen, Stanford University
Todd Deutsch, National Renewable Energy Laboratory
Huyen Dinh, National Renewable Energy Laboratory
Kazunari Domen, University of Tokyo (Japan)
Arnold Forman, University of California, Santa Barbara
Nicolas Gaillard, Hawaii Natural Energy Institute
Roxanne Garland, U.S. Department of Energy
Clemens Heske, University of Nevada Las Vegas
Thomas Jaramillo, Stanford University
Alan Kleiman, University of California, Santa Barbara
Eric McFarland, University of California, Santa Barbara
Eric Miller, Hawaii Natural Energy Institute
Mahendra Sunkara, University of Louisville
Kazuhiro Takanabe, University of Tokyo, (Japan)
John Turner, National Renewable Energy Laboratory

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Document Descriptions

The following PEC documents will be available for review. Please fill out the request to comment form to receive information on how to access the review documents. 

Introduction: Offers PEC researchers efficiency definitions and in-depth reviews of the techniques and protocols associated with the development of materials for PEC water splitting.

Efficiency Definitions: Describes various efficiency values and their proper usage, including solar-to-hydrogen efficiency, applied bias photon-to-current efficiency, incident photon-to-current efficiency, and absorbed photon-to-current efficiency.

Electrode Preparation and Surface Area: Describes issues related to electrode preparation, including contacts, seals, substrate choice, electrode mounting methods, deposition techniques to fabricate photoactive films, and electrode surface area measurements.

PEC Test and Cell Setup: Describes the basic PEC test setup, including the electrochemical test cells, electrical connections, and choice of electrolyte and counter electrode.

Spectral Standards and Calibration: Describes the origin of and how to simulate a standard AM1.5 G solar spectrum.

Catalyst Surface Treatment: Describes several methods widely used in the PEC community to enhance surface catalysis.

PEC Characterization Flow Chart: Provides a suggested list of experiments to perform when determining the viability of a material for PEC water-splitting, including the preferred order of testing and the requirements for passing the tests.

UV-VIS:  Explains a simple and fast technique that can yield the size and nature of the band gap of a material and is performed typically in transmission and diffuse reflectance configurations.

Illuminated Open Circuit Potential: Describes how to make an OCP measurement to determine semiconductor conductivity type and flatband potential.

Mott-Schottky: Explains the classic Mott-Schottky method to determine flatband potential and the free charge carrier density of a photoelectrode.

3-Electrode J-V Analysis and Photocurrent Onset: Describes two related methods to determine the potential range of photocurrent generation, the saturated photocurrent density, and the flatband potential.

Incident Photon-to-Current Efficiency (IPCE) and Photocurrent Spectroscopy:  Discusses the IPCE technique, which compares photocurrent vs. incident photon flux as a function of wavelength.  Discussion includes the theoretical background of charge transfer, experimental setup, photon quantification techniques, data manipulation, and common mistakes throughout.  Photocurrent spectroscopy to determine bulk optical band gap is covered also.

2-Electrode Short-Circuit Current Density and J-V Experiments: Describes a 2-electrode short-circuit experiment and a 2-electrode current density-voltage (J-V) experiment to determine the solar-to-hydrogen conversion efficiency and an applied bias photocurrent efficiency, respectively, under an AM 1.5 G spectrum.

Hydrogen and Oxygen Detection from Photoelectrodes: Discusses true PEC "water splitting" efficiency, which can only be confirmed by H2 and O2 identification and quantification.  Also discussed are experimental setups, equipment required, system considerations, and data processing for photoelectrochemical gas detection by gas chromatography.

Stability Test: Describes two photocurrent durability tests: (1) a 2-electrode, zero-bias test and (2) a 2-electrode test with an applied bias.

PEC Glossary: Defines terms relevant to photoelectrochemistry and semiconductors to guide readers on the nomenclature and terms used through the technical review paper.

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