iea-hia task 26 research and development progress in renewable hydrogen production through...

Energy Procedia 29 ( 2012 ) 438 – 444

1876-6102 © 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association.doi: 10.1016/j.egypro.2012.09.051

World Hydrogen Energy Conference 2012

IEA-HIA Task 26 research and development progress in renewable hydrogen production through photoelectrochemical

water splitting

Eric L. Miller a* aU.S. Department of Energy, 1000 Independence Ave. SW, Washington, D.C. 20585, USA

Abstract

Photoelectrochemical (PEC) hydrogen production, using sunlight to directly split water, is one of the key enabling technologies for a future where hydrogen is widely deployed as an energy carrier. However, the “traditional” semiconductor-based PEC material systems studied to date, including simple metal oxides such as TiO2, WO3 and Fe2O3, have not been successful in meeting all the performance, durability and cost requirements for practical hydrogen production. Technology-enabling advances in the development of new, advanced PEC materials and systems have been needed. Toward this end, the International Energy Agency’s Hydrogen Implementation Agreement (IEA-HIA) Task-26, working in close conjunction with “Working Group on PEC Hydrogen Production” in the Fuel Cell Technology Program at the U.S. Department of Energy, has brought together experts in materials theory, synthesis, characterization and analysis from research sectors across the world. This endeavor has resulted in exciting recent progress over a broad range of PEC materials classes, including high efficiency crystalline semiconductors (e.g., III-V materials), promising thin-film semiconductors (including Fe2O3- ,WO3-, and CuGaSe2- based films), novel photocatalyst powders (such as Cs-Modified WO3) and innovative photocatalyst nano-particles (e.g., MoS2). The research and development progress in these important PEC materials classes will be summarized, and key implications discussed. © 2012 Published by Elsevier Ltd.

Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association Keywords: Fuel Cells; Hydrogen; Photoelectrochemical; Production

*Tel.: 01-202-287-5829; fax: 01-202-586-2373. E-mail address: [email protected].

Available online at www.sciencedirect.com

© 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association

Eric L. Miller / Energy Procedia 29 ( 2012 ) 438 – 444 439

1. Introduction

Photoelectrochemical (PEC) hydrogen production using sunlight to directly split water is one of the paramount enabling technologies for a future where hydrogen is widely deployed as an energy carrier. The simple concept of a PEC solar water-splitting system based on a semiconductor photoelectrode device, where sunlight shining on device is converted to chemical energy for separating H2O molecules into hydrogen and gas, is illustrated in Figure 1. PEC Hydrogen Production is attractive among the solar-to-hydrogen (STH) conversion technologies for a number of reasons, including:

Efficient STH conversion is possible at low temperature operations. Relatively simple “low-technology” implementations can be designed which are applicable to

large-scale central production as well as small scale end user production. Strong synergies exist with contemporary materials research efforts in photovoltaics (PV) and

nano-technology. Interesting off-shoot technologies using PEC in chemical processing are possible.

Figure 1: Illustration of PEC solar hydrogen production using a semiconductor photoelectrode. Renewable solar hydrogen production via PEC water splitting has been successfully demonstrated

on the laboratory scale using currently available materials systems, but challenges remain in meeting all targets in STH conversion efficiency, durability and cost. Multi-layered oxide material systems of reasonable durability and cost (for example, incorporating TiO2, WO3 or Fe2O3) have demonstrated 3-5% STH performance, but this falls short of the longer term targets of 10-20% STH for practical implementation of PEC technologies [1, 2]. The benchmark for PEC performance has been established in crystalline multi-junction GaAs/GaInP2 photoelectrode systems developed at the National Renewable Energy Laboratory (demonstrating 12-16%STH) [3]. These high-performing devices still, however, remain limited by high cost and low durability

For PEC hydrogen production to be practical, technology-enabling advances are needed in the development of new, advanced materials systems with high efficiency, long durability and low cost. Toward this end, the IEA-HIA Task-26, working in close conjunction with the U.S. Department of Energy’s (DOE) “PEC Working Group” brought together international experts in analysis, theory, synthesis and characterization from the academic, industry and national laboratory research sectors across the world, with four overarching objectives, including:

440 Eric L. Miller / Energy Procedia 29 ( 2012 ) 438 – 444

Intensification of international collaboration, making use of extended fields of expertise in areas of materials theory, synthesis and characterization, as well as data and data-base management;

Advancement of photoelectrode materials science, particularly addressing the discovery of new practical materials, with bulk and surface properties specifically engineered to meet the requirements for efficient and stable PEC water splitting;

Demonstration of stable and efficient water splitting in the leading materials systems, using standardized performance characterizations and round-robin testing procedures; and

Promotion of photolysis of water through publications, education and outreach program.

Facilitating research and development of new semiconductor materials for stable and efficient PEC hydrogen production systems is the primary goal. In order to meet this goal a comprehensive “Subtask” structure was established, as illustrated below in Figure 2, serving as the central organizational framework for R&D activities. Task-26 has relied heavily on individual subtasks and subtask leaders to coordinate collaborative efforts in international PEC R&D for facilitating the PEC materials breakthrough process.

Figure 2: Subtask definitions of the IEA-HIA Task-26.

Within this subtask structure, activities associated with subtasks C, D, E, T and S contribute to the

development of a comprehensive “tool-chest” comprised of PEC-related materials research tools. This “tool-chest” is then being used in the research and development of promising PEC focus materials systems (subtask M) using the following strategies:

Further development of the “standard” PEC semiconductor thin-films and nano-structures for

higher efficiencies (e.g., tungsten trioxide, iron oxide, etc.) Development of efficient PV semiconductor thin-films and nano-structures for effective use in

PEC (e.g., copper chalcopyrites and amorphous silicon compounds) Development of new processes and technologies to reduce the cost and enhance the stability of

high-performance crystalline materials (e.g., III-V nitrides) Discovery and development of “new” materials classes based on the accumulated knowledge-

base from PEC and PV research efforts to date (e.g., WS2 and MoS2 nanoparticle systems). Collaboration and cooperation are critical to the success of such a broad-ranging scientific

endeavour. The international outreach and expansion of cooperative and collaborative activities between


the US DOE PEC Working Group and the international research community in areas related to PEC materials discovery and development have been central to the success of the IEA-HIA Task-26. Combining ever-advancing world-class capabilities in analysis, theory, synthesis and characterization is viewed as the surest path to the needed scientific advances in PEC semiconductor materials. With this in mind, Task-26 has relied on its international base, coordinating numerous international meetings held in conjunction with important materials and electrochemical conferences. Synergistic activities among the US DOE Working Group projects, European PEC projects such as “NanoPEC”, and Asian research projects such as those in Japan and South Korea have paid strong dividends, as evidenced in recent progress and results. 2. Technical Progress

Over the tenure of the IEA-HIA Task 26, the task’s research methodology has paid dividends in terms of technical achievements in PEC materials research and development. The tools developed in the Task-26 research arsenal (for example, in the subtask A, C, S and T activities) have been effectively utilized toward the advancement of PEC materials systems (in the subtask M activities). Major accomplishments resulting from these activities have been documented in numerous Task reports, and are being further organized and documented in a series of updated materials “White Papers” for incorporation into the Task-26 Final Report. Broadly speaking, numerous important accomplishments have been achieved over a broad spectrum of PEC materials over the duration of Task-26. Some of the most recent notable achievements have included:

Achievement of new benchmark performance in oxide-based materials, specifically in iron-oxide based material systems as a result of the EU NanoPEC Project [4].

Achievement of new benchmark performance levels in III-V materials multi-junction photoelectrodes at the National Renewable Energy Laboratory (NREL) as a result of the US PEC Working Group efforts, shown in Figure 3a [5, 6].

Achievement of new benchmark performance levels in copper-chalcopyrite thin film materials in multi-junction photoelectrode configurations at the University of Hawaii/MVSystems as a result of the US PEC Working Group efforts [7].

Successful demonstration of Z-scheme photocatalyst systems and screening of numerous photocatalyst materials in research institutes in Japan, including AIST and TUS [8, 9, 10, 11].

Successful demonstration of enhanced performance heterojunction thin film material systems in South Korea at POSTECH [12].

Development at Stanford University of new quantum-confined MoS2 nano-particle catalysts and concurrent development of novel macro-structures for integration into practical photoelectrochemical hydrogen production devices, illustrated in Figure 3b [13, 14].

Continued work on the refinement of the “Standardized Methodologies for PEC Measurements and Reporting” effort. . Agreements are being negotiated with Springer to publish the documents in book form with assigned editors (Huyen Dinh of NREL, Eric Miller of DOE, and Zhebo Chen of Stanford University) [15].

Publication of hundreds of PEC articles in scientific journals and in conference proceedings by Task-26 Experts and associated research groups.

Publication of two important books on PEC Hydrogen Production with major contributions from the Task-26 Experts [16, 17].


As of 2012, the IEA-HIA Task 26 is in its final year of tenure. The primary activities have started winding down in preparation for final Task documentation. Additionally, new proposals are being developed for integrating ongoing PEC work into a future IEA-HIA Task framework.

TCO scaffold

MoS2 nano-particle catalysts(b)

enhanced 0-bias PEC operating point

(a)

Figure 3: (a) New benchmark performance in PEC solar water-splitting from NREL GaAs/GaInP2 devices, demonstrating increases in STH conversion efficiency from ~12 to over 16%; and increases in durability from ~10 to over 100 hours; (b) New approach to PEC water splitting using bandgap-tuned MoS2 nano-catalysts loaded onto transparent-conductive-oxide (TCO) scaffolding to form a H2 producing photoelectrode.

3. Future Work

As the IEA-HIA Task-26 is approaching the end of its tenure, the technical advances realized through implementation of the task’s R&D methodologies are being incorporated into a Task Final Report. The primary content of this report will comprise the up-to-date PEC materials “White Papers”, currently under preparation by Task Experts, covering specific materials topics including:

III-V crystalline semiconductors material systems Fe2O3 based thin-film materials WO3 based thin-film materials I-III-VI2 thin-film semiconductor materials (e.g., CuGaSe2) Molybdenum disulfide (MoS2) nanostructured photocatalysts Bismuth vanadate (BiVO4) materials Tantalum oxi-nitride (TaON) materials PEC Materials Theory Updates New oxide materials and material systems

Continued work on documentation and on information management is the current priority as the task

continues into its final year. In addition, potential follow-on PEC work in a future IEA-HIA Task structure has been discussed with Task Experts; One conceptual approach integrating PEC into a broader Task focused on “Renewable Hydrogen” (along with Bio-Hydrogen, Solar-Thermochemical Hydrogen, and others) was considered with support from the Experts. Independent of the specific manifestation in the IEA-HIA task structure, solar hydrogen production via PEC water splitting will remain a strong international priority. Despite the significant scientific challenges, a world-class team of researchers continues to make impressive progress in this field.


Acknowledgements

The author would like to express “Mahalo Nui Loa” to the WHEC, to the US. DOE Fuel Cell Technologies Program, to the International Energy Agency Hydrogen Implementing Agreement, and especially to all the dedicated and IEA-HIA Task-26 Researchers (for their inspired and inspirational work).

References

[1] DOE EERE Fuel Cells Technologies Program: Multi-Year Research, Development and

Demonstration Plan: http://www1.eere.energy.gov/hydrogenandfuelcells/mypp/ 2009. [2] B.D James., G.N. Baum, J. Perez, K.N Baum, Technoeconomic Analysis of

Photoelectrochemical (PEC) Hydrogen Production, https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/pec_technoeconomic_analysis.pdf, 2009.

[3] O. Khaselev, J. A. Turner, A Monolithic Photovoltaic/Photoelectrochemical Device for Hydrogen Production via Water Splitting, Science, 1998, 280, 425-427.

[4] NanoPEC Project Publications website: http://nanopec.epfl.ch/publications [5] T. Deutsch, Semiconductor Photoelectrodes for Direct Water Splitting, Pacifichem 2010

Congress, Honolulu, HI. December 15-20, 2010. [6] J. A. Turner and T. Deutsch, US D.O.E. Hydrogen Program Annual Merit Review Meeting

2011, Arlington, VA, May 9-13, 2011. http://www.hydrogen.energy.gov/pdfs/review11/pd035_turner_2011_o.pdf .

[7] A. Madan, J. Kaneshiro, et al., US D.O.E. Hydrogen Program Annual Merit Review Meeting 2011, Arlington, VA, May 9-13, 2011. http://www.hydrogen.energy.gov/pdfs/review11/pd053_madan_2011_o.pdf .

[8] T. Arai, Y. Konishi, Y. Iwasaki, H. Sugihara, and K. Sayama, High-Throughput Screening Using Porous Photoelectrode for the Development of Visible-Light-Responsive Semiconductors, J. Comb. Chem, 2007, 9, 574–581.

[9] H. Kusama, N. Wang, Y. Miseki, and K. Sayama, Combinatorial Search for Iron/Titanium-Based Ternary Oxides with a Visible-Light Response, J. Comb. Chem, 2010, 12, 356–362.

[10] M. Higashi, R. Abe, A. Ishikawa, T. Takata, B. Ohtani, and K. Domen, Z-scheme Overall Water Splitting on Modified-TaON Photocatalysts under Visible Light ( < 500 nm), Chem. Lett 2008, 37, 138-139.

[11] H. Arakawa, Z. Zou, K. Sayama, and R. Abe, Direct Water Splitting By New Oxide Semiconductor Photocatalysts Under Visible Light Irradiation, Pure Appl. Chem 2007, 79, 1917–1927.

[12] POSTECH PEC Group website: http://ecocat.postech.ac.kr/ [13] J. H. Nielsen, L. Bech, K. Nielsen, Y. Tison, K. P. Jørgensen, J. L. Bonde, S. Horch, T. F.

Jaramillo, and I. Chorkendorff, Combined spectroscopy and microscopy of supported MoS2 nanoparticles” Surf. Sci., 2009, 603, 1182-1189.

[14] T. F. Jaramillo, et al., US D.O.E. Hydrogen Program Annual Merit Review Meeting 2011, Arlington, VA, May 9-13, 2011. http://www.hydrogen.energy.gov/pdfs/review11/pd033_jaramillo_2011_o.pdf .

[15] Z. Chen, T. F. Jaramillo, T. G. Deutsch, A. Kleiman-Shwarsctein, A. Forman, N. Gaillard, R. Garland, K. Takanabe, C. Heske, M. Sunkara, E. W. McFarland, K. Domen, E. L. Miller, J. A. Turner, H. N. Dinh, Accelerating Materials Development for Photoelectrochemical (PEC)


Hydrogen Production: Standards for Methods, Definitions, and Reporting Protocols , Journal of Materials Research 2010, 25, 3-16.

[16] R. Van de Krol, M. Gratzel editors, Photoelectrochemical Hydrogen Production, Springer, 2011. [17] L.Vayssieres editor, On Solar Hydrogen & Nanotechnology, Wiley, 2010.

iea-hia task 26 research and development progress in renewable hydrogen production through...

Documents