SCIENTIFIC COMMITTE

PLENARY TALKS

NanoMaterials for Oxygen Reduction Reaction: Metal Center and Substrate Effects

Nicolas Alonso-Vante

IC2MP - UMR-CNRS 7285, University of Poitiers

4, rue Michel Brunet, F-86022, Poitiers, France

e-mail: nicolas.alonso.vante@univ-poitiers.fr

Transition-metal materials in nanodivided form are essentially devoted to study the electrocatalytic reduction of molecular oxygen (ORR) in acid medium. The tailoring per se of efficient and selective cathode catalyst, for the same process, is interesting and still challenging. In this sense, a significant progress has been achieved in the search of catalysts based on cluster-like mono-, bi-metallic, chalcogenides, and oxide substrates. The strong- nanocatalyst oxide interaction observed with the substrate is favorable for electrocatalysis. All such effects are beneficial for the low temperature hydrogen fuel cell system, where the sluggish kinetics and high over-potentials associated with ORR are significant issues. Several strategies have been devised, e.g., alloying platinum with 3d transition metals (M = Co, Ni, Fe, etc.); second using mixed-conductivity materials as substrates, and third, developing non-precious metal centers. These approaches not only may reduce costs, but the lowering of precious metals loading must maintain a higher oxygen reduction activity than pure Pt in acidic media. The underlying phenomena regarding the synthesis and catalytic activity of nano-scale catalyst will be discussed in this lecture.

Professor at the University of Poitiers, Nicolas Alonso-Vante co-directs the group of Electrocatalysis since his appointment in 1997. Over more than two decades he has developed materials in the nanodivided scale based on transition metal and chalcogenides in metallic and semiconducting form in Germany and France. Using facile chemical routes he has pioneered the use of non-platinum and non-precious metal catalysts center chalcogenides in order to understand the complex process of the oxygen reduction reaction process, an important technological reaction in low temperature fuel cells. Other interest of such materials in combination with light harvesting are devoted to split water into hydrogen and oxygen, and photocatalysis. He is the author of over 140 publications, book chapters, editor of a two-volume e-book of electrochemistry in Spanish and holds 2 US- and 2 German patents; his work has been widely cited. He has received the awards of the National Polytechnic Institute-Mexico as a R&D distinguished graduate, and of the Mexican Council of Technology SNI-III recognition as a Mexican researcher working outside Mexico. He is also a member of the International Society of Electrochemistry, the Electrochemical Society, and the Bunsengesellschaft für Physikalische Chemie. He obtained the degrees of Docteur Troisième Cycle and Doctorat d’Etat from the University of Strasbourg. Under the auspices of the Alexander von Humboldt foundation he was awarded a two years Post-Doc fellowship at the Hahn-Meitner-Institut-Berlin (now Helmholtz-Zentrum Berlin), where he further worked as a senior scientist in the department of solar energy over ten years.

Challenges in the first-principles design of electrocatalyst materials
for fuel cells

Perla B. Balbuena

Department of Chemical Engineering

Texas A&M University

College Station, TX, 77843

An important problem in low-temperature fuel cell technology is improving the catalytic efficiency of the electrocatalyst where the oxygen reduction reaction (ORR) takes place. The ORR is a kinetically slow reaction in which molecular oxygen is reduced and combines with protons producing water. Platinum is the most widely used ORR electrocatalyst. However, it is extremely expensive and the relatively sluggish ORR kinetics on Pt surfaces limits its catalytic efficiency. Pt-based alloys have been shown to yield comparable or better activity as ORR electrocatalysts compared to pure Pt surfaces. Thus, these less expensive alternatives are being extensively studied in proton-exchange membrane fuel cell environments to verify their stability and durability at various fuel cell operational conditions. We will discuss our recent findings based on density functional theory and classical molecular dynamics methodologies that permitted us to do an extensive evaluation of Pt(shell)-transition metal (core) systems. We start with DFT analysis of cores made of pure metals (3-d, 4-d, or 5-d type) and then we investigate changes and effects on activity and stability caused by the introduction of bimetallic or trimetallic cores. At relatively high oxidative conditions we examine buckling of the surface atoms due to changes in surface composition and presence of adsorbates, and the dynamic evolution of core-shell catalyst surfaces under increasing oxidation conditions obtained from classical MD simulations. We characterize the most stable surface structures and investigate how water may affect the stabilization of the oxygenated intermediates as a function of pH and electrochemical potential. Finally, we introduce alternative catalyst designs that may offer enhanced activity and durability properties.

Prof. Perla B. Balbuena obtained her PhD from the University of Texas at Austin, MSc from the University of Pennsylvania, and BS from Universidad Tecnologica Nacional, Argentina, all in Chemical Engineering. From 1997 to 2004 she was Assistant and then Associate Professor at the University of South Carolina. In 2004, she was appointed as full professor of the Department of Chemical Engineering at Texas A&M University, and since 2006 she is also full professor of the Materials Science and Engineering Program at Texas A&M. Her research centers on first-principles computational materials design, with main areas in catalysis, electrocatalysis, and nanomaterials. She has done pioneering work in computational analysis of lithium ion batteries and fuel cell materials, and currently investigates also other areas such as CO2 capture. Dr. Balbuena is author of more than 150 scientific articles in peer-reviewed journals and has co-edited five books in her areas of specialization

A Combinatorial and Distributed Search for Semiconducting Oxides that Photoelectrolyze Water

Bruce Parkinson

Department of Chemistry

School of Energy Resources

University of Wyoming

Laramie, Wyoming 82071

The increasing need for carbon free energy has focused renewed attention on solar energy conversion. Although photovoltaics offer an attractive method for the direct conversion of solar energy to electricity, it does not directly produce stored energy or fuels. Direct photoelectrolysis of water has the advantage of converting solar energy directly to hydrogen, an ideal non-carbon energy carrier, by replacing both a photovoltaic array and an electrolysis unit with one potentially inexpensive device. Semiconducting metal oxides could potentially be stable under illumination in an aqueous electrolyte for many years making them the most promising materials for solar water photoelectrolysis. The problem is that no known oxide semiconductor can efficiently carry out this process. We have developed a simple, high-throughput combinatorial approach to prepare and screen many complex oxides for water photoelectrolysis activity. The approach uses ink jet printing of overlapping patterns of metal oxide precursors, metal nitrate salts, onto conductive glass substrates. Subsequent firing produces metal oxide phases that are screened for photoelectrolysis activity by measuring photocurrents produced by scanning a laser over the printed patterns in aqueous electrolytes. Several promising and unexpected compositions have been identified. We are in the process of optimizing and understanding the physical structure, electronic structure and catalytic ability these new photocatalysts. In addition, due to the millions of possible combinations to be printed and screened, we have developed a distributed screening approach that uses simple and inexpensive printing and screening devices such as Lego Mindstorm® kits that are designed to enlist many undergraduate student researchers into the search for the “Holy Grail” of materials. The Solar Hydrogen Activity research Kit or SHArK project has now expanded to over forty sites.

Bruce Parkinson received his BS in chemistry at Iowa State University in 1972 and his PhD in chemistry from Caltech in 1977 and was a post-doctoral scientist at Bell Laboratories in 1978. He then spent time at the Ames Laboratory and the Solar Energy Research Institute (now known as the National Renewable Energy Laboratory) in Golden, Colorado. He moved to the Central Research and Development Department of the DuPont Company in 1985 and in 1991 he became Professor of Chemistry at Colorado State University until his departure in 2008 to join the Department of Chemistry and the School of Energy Resources at the University of Wyoming. His current research covers a wide range of areas including materials chemistry, surface chemistry and photoelectrochemical energy conversion. He is a Fellow of the American Association for the Advancement of Science has more than 200 peer-reviewed publications and holds 5 US patents.

Solar Energy Conversion and Environmental Remediation using Inorganic Semiconductor-Liquid Interfaces: The Road Travelled and the Way Forward

Krishnan Rajeshwar

Distinguished University Professor and Associate VP For Research

University Of Texas At Arlington

Unlike their solid-state counterparts, semiconductor-liquid junctions are versatile in that the incident solar energy can be stored in the form of chemical fuels. Another attractive application is the use of irradiated oxide semiconductor-coated surfaces for self-cleaning and anti-fogging. A history-tinged perspective is first given on what has been accomplished in the above “photoelectrochemical” schemes over the 35 year timeframe from 1975 through 2010. Progress in this field was aided by the infusion of new concepts and contributions from the materials chemistry and physics communities. A related aspect of discussion is how the active semiconductor material has evolved both chemically and morphologically in these applications. It is shown that despite impressive research advances, only a handful of the above concepts (e.g., dye-sensitized solar photon conversion, self-cleaning and anti-fogging surfaces) have made the successful transition from the laboratory to the marketplace. Focusing on the active semiconductor material, a key parameter in life cycle analyses of solar energy materials and devices is the energy payback time; i.e., the time it takes for the energy needed for material synthesis to be recovered back. The energy payback time can be effectively shrunk by deploying “mild” (low-temperature) synthesis routes. Electrodeposition is an eminently attractive candidate in this regard. Another strategy for reducing the energy payback time is to make the synthesis efficient, both in terms of energy requirement and time duration. In this vein, the merits of solution combustion synthesis will be discussed. The talk will finally focus on the use of the above synthesis methodologies for preparing new generations of inorganic oxide semiconductors for solar fuel and environmental remediation applications.

Dr. Rajeshwar is a Distinguished University Professor and Associate VP for Research at the University of Texas at Arlington. He is also the founding director of the Center for Renewable Energy Science & Technology (CREST) on campus. He serves as the Editor of the Electrochemical Society Interface and on the editorial boards of electrochemical journals. After post-doctoral training at Colorado State University, he joined UT Arlington in 1983. His research interests span a wide spectrum and include photoelectrochemistry; solar energy conversion; renewable energy; materials chemistry; semiconductor electrochemistry; and environmental chemistry. Dr. Rajeshwar is a Fellow of the Electrochemical Society and received the Energy Technology Division Research Award of the Electrochemical Society in 2009. He has edited books, special issues of journals, and conference proceedings and is the author of over 450 refereed publications. He can be reached at rajeshwar@uta.edu This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Synthesis of substituted pyrochlores for hydrogen production from liquid fuels

Dr. James J. Spivey

Louisiana State University

Fuel processors designed to produce hydrogen-rich gas for fuel cells require catalysts for the initial reforming of the fuel that are thermally stable and resistant to deactivation at extreme conditions—typically 900-1000 deg C and low O/C and S/C ratios. Pyrochlores are crystalline oxides of the general formula A2B2O7, in which catalytically active metals can be substituted at the B-site, and various tetravalent rare earth metals can be substituted at the A site to give a catalyst with inherent activity and resistance to deactivation by carbon deposition. This talk will present results on synthetic and actual fuels and discuss the stability and activity of these materials at practical condition.

Dr. James J. Spivey is the J. M. Shivers and C.M. Eidt, Jr. Professor of Chemical Engineering at Louisiana State University. He is Editor-in-Chief of Catalysis Today, and Editor of the Royal Society of Chemistry's Catalysis book series. He has written/edited a total of 17 books over the last 15 years, and has authored more than 100 publications. His research focuses on the development and characterization of heterogeneous catalysts for applications such as hydrogen production, clean fuels, environmental catalysis and synthesis of chemical intermediates from simple carbon feedstocks such as methane. Other research activities include the application of the principles of heterogeneous catalysis to catalytic combustion, control of sulfur and nitrogen oxides from combustion processes, acid/base catalysis (e.g., for condensation reactions), hydrocarbon synthesis, and the study of catalyst deactivation. He has managed over $30 million in sponsored projects over the past 20 years. He currently is Director of the Center for Atomic-level Catalyst Design at LSU one of 46 new multi-million-dollar DOE Energy Frontier Research Centers. He leads a team of 21 investigators from 10 leading research universities with demonstrated expertise in computational catalysis; advanced materials preparation methods, surface spectroscopy, and experimental testing.

Breakthrough performance from steam reformers using foil supported catalysts

William Whittenberger

President Catacel Corp.,
President EcoLake Enterprises, LLC,
Ohio, USA

The Catacel SSR® is a drop-in replacement for the loose ceramic catalyst media in the stationary steam reforming process that has been used for many years to produce hydrogen from natural gas in large industrial plants. The SSR is a permanent catalyst-coated metal foil replacement with specially designed corrugation and flow channels that can be easily connected and installed into the reformer tubes. The SSR eliminates the periodic replacement that is required for ceramic packed beds. The Catacel approach combines high performance reaction materials with high performance heat transfer ability. In many reactions such as steam reforming that are heat transfer limited, it is possible to achieve higher throughput rates. The fins of the SSR are arranged for superior heat transfer that enables the use of lower furnace temperatures with consequent overall system energy savings and extended tube and furnace life. In addition, they are crush-proof for exceptional long life. Catalysts similar to these have been delivering cost and energy benefits to various fuel cell systems for many years. These products improve efficiency and durability by providing lighter components with a higher surface area. An early version of SSR has been installed in a plant in Turkey and has been operating for nearly four years at full capacity. The newest version, with considerably improved performance, was installed in a commercial H2 plant in Mexico early in 2012. We will share experiences and performance data from those installations.

William A. Whittenberger is president of Catacel Corp., Garrettsville, Ohio, and president and owner of EcoLake Enterprises, LLC, Leavittsburg, Ohio. He has broad management and technical experience in machinery, capital goods, and automotive supply industries. Managed an industrial catalytic converter manufacturing plant. Managed all product development, quality planning, equipment, and manufacturing efforts for two new automotive catalyst products from concept through pilot operation. He is experienced in modern manufacturing and quality methods; also in patent law, filings, and infringement (domestic and foreign). He is member of the Society of Automotive Engineers, ASM Internatinal and the American Society of Mechanical Engineers. He holds 28 patents, many of them related to catalytic converters