本田財団レポート No.141
第 32 回本田賞授与式 記念講演（2011 年 11 月 17 日）「表面の科学とエコテクノロジーに対する分子的理解」
米国カリフォルニア大学バークレー校化学科教授

ガボール・ソモルジャイ博士

Molecular Understanding of the Science andEcotechnologies of Surfaces
Commemorative lecture at the 32nd Honda PrizeAward Ceremony on the 17th November 2011

Dr. Gabor A. Somorjai
Professor of Chemistry, University of California, Berkeley
University Professor, University of California Systemガボール・ソモルジャイ博士
米国カリフォルニア大学バークレー校化学科教授
Professor of Chemistry, Chemistry Department,
University of California, Berkeley

Curriculum Vitae for Dr. Gabor A. Somorjai■生まれ
1935年5月4日
■学 歴
1956年
1960年

■職 歴
1960年～64年
1964年～現在
1964年～現在■経（76歳）ハンガリー・ブダペスト（米国市民）
ハンガリー・ブダペスト工科大学化学工学科卒業
米国カリフォルニア大学バークレー校化学科博士課程修了

IBM 研究員（ニューヨーク州ヨークタウンハイツ）
カリフォルニア大学バークレー校化学科教授
ローレンスバークレー国立研究所上級科学者兼ディレクター

歴

1956年、ブダペスト工科大学化学工学科4年在学時にハンガリー革命が勃発し米国へ移住。1960年にカリフォルニ
ア大学バークレー校で博士号を取得。
卒業後はニューヨーク州ヨークタウンハイツにある IBM研究所で研究員として勤務。1962年、米国市民権を取得。
1964年、カリフォルニア大学バークレー校化学科助教授に就任（1967年同科准教授、1972年同科教授）。同時にロー
レンスバークレー国立研究所先端材料センター材料科学部
門の上席科学者兼表面科学・触媒化学プログラム・ディレクターを兼務。
表面科学、不均一系触媒、固体化学の分野で1,000以上の科学論文を発表し、「表面科学の父（もしくは開拓者）」とも呼ばれる。ソモルジャイ博士の下で140名が博士号を取得し、250名以上の博士研究員（ポスドク）が学んだ。その内、現在約100名が大学で教鞭をとる他、産業界でも多くの卒業生が活躍中。
世界中の研究者が読む博士が著した教科書には、「表面化学の原則」Prentice Hall 社(1972年)、「モノグラフ・固体表面の吸着単分子膜」Springer-Verlag 社(1979年)、「二次元の化学～表面」Cornell 大学出版(1981年)、「表面化学と触媒入門」Wiley-Interscience 社(1994年)、「表面化学と触媒入門・第2版」Wiley 社(2010年)等がある。

■BORN
4th May, 1935, Budapest, Hungary ( U.S. citizen)■DEGREES
1960 Ph.D., Chemistry, University of California, Berkeley (UCBerkeley), CA
1956

B.S., Chemical Engineering, Technical University,
Budapest, Hungary■APPOINTMENTS
1964 – Present Professor, Department of Chemistry, UCBerkeley
1964 – PresentFaculty Senior Scientist, Lawrence Berkeley
National Laboratory

1960 –1964

Research Staff, IBM, Yorktown Heights,New York■SELECTED HONORS
Somorjai was born in Budapest, Hungary, on May 4, 1935.
He was a fourth year student of Chemical Engineering at theTechnical University in Budapest in 1956 at the outbreak of
the Hungarian Revolution. He left Hungary and emigrated tothe United States, where he received his Ph.D. degree inChemistry from the University of California, Berkeley in 1960.
He became a U.S. citizen in 1962.
After graduation, he joined the IBM research staff in
Yorktown Heights, NY, where he remained until 1964. At thattime, he was appointed Assistant Professor of Chemistry at theUC Berkeley. In 1967, he was named Associate Professor, andin 1972 promoted to Professor. Concurrent with his faculty
appointment, he is also a Faculty Senior Scientist in theMaterials Sciences Division, and Director of the Surface
Science and Catalysis Program at the Center for Advanced
Materials, at the Lawrence Berkeley National Laboratory.
He was appointed University Professor by the UC Board ofRegents in March of 2002.
Somorjai has educated 140 Ph.D. students and more than250 postdoctoral fellows, about 100 of which hold faculty
positions and many more are leaders in industry. He is theauthor of more than 1000 scientific papers in the fields ofsurface chemistry, heterogeneous catalysis, and solid statechemistry. He has written three textbooks, Principles ofSurface Chemistry, Prentice Hall, 1972; Chemistry in Two
Dimensions: Surfaces, Cornell University Press, 1981
Introduction to Surface Chemistry and Catalysis,
Wiley-Interscience, 1994 and Introduction to Surface
Chemistry and Catalysis, Second Edition, Wiley 2010; and amonograph, Adsorbed Monolayers on Solid Surfaces,Springer-Verlag, 1979

■受賞歴 Awards and Honors
20112009

2008
2007
2006
2003
20022000

1998
1997
1995
1994
1990
1989

1986
1983
1982
1981
1979
1978
1977
1976
1972
1969

ENI New Frontiers of Hydrocarbons PrizeBBVA Foundation Frontiers of Knowledge Award in Basic Sciences
Senior Miller Fellow, Miller Institute, UC, Berkeley
Japanese Society for the Promotion of Science Award
Excellence in Surface Science Award from the Surfaces in Biointerfaces Foundation
Fellow of the American Chemical Society
Honorary Membership, Chemical Society of Japan
Priestley Medal from the American Chemical Society
Langmuir Prize from the American Physical Society
Remsen Award from the Maryland Section of the ACS
Honorary Fellow, Cardiff University
Cotton Medal, Texas A&M University
National Medal of Science
American Chemical Society Award for Creative Research in Homogeneous or Heterogeneous Catalysis
Linus Pauling Medal for Outstanding Accomplishment in Chemistry, American Chemical Society,Puget Sound, Portland and Oregon Section
Wolf Prize in Chemistry
Von Hippel Award, Materials Research Society
Chemical Pioneer, American Institute of Chemists
Adamson Award in Surface Chemistry, American Chemical Society
Honorary Membership in Hungarian Academy of Sciences
Peter Debye Award in Physical Chemistry, American Chemical Society
Senior Distinguished Scientist Award, Alexander von Humboldt Foundation
E.W. Mueller Award, University of Wisconsin
Henry Albert Palladium Medal
Member, American Academy of Arts and SciencesFellow, American Association for the Advancement of Science
Distinguished Scholar for Exchange with China
Colloid and Surface Chemistry Award, American Chemical Society
Member National Academy of Sciences
Miller Professorship, UC Berkeley
Emmett Award, American Catalysis Society
Kokes Award, Johns Hopkins University, Baltimore, Maryland
Elected Fellow, American Physical Society
Unilever Visiting Professor, University of Bristol, United Kingdom
Guggenheim Fellowship
Visiting Fellow, Emmanuel College, Cambridge, United Kingdom■会員 Memberships
National Academy of Science
American Academy of Arts and Sciences
American Chemical Society
American Physical Society (Fellow)
American Association for the Advancement of Science (Fellow)
Cosmos Club, Washington DC
このレポートは、2011 年 11 月 17 日 東京、帝国ホテルにおいて行なわれた第 32 回本田賞授与式記念講演の要旨をまとめたものです。
This report is the gist of the commemorative lecture at the 32nd Honda Prize Award Ceremony at the Imperial Hotel, Tokyo on
17th November 2011.

Molecular Understanding of the Scienceand Ecotechnologies of Surfaces
Gabor A. Somorｊai

I am deeply honored and grateful to receive the Honda Prize for my research in surface
science and catalysis, which has led to a molecular understanding of these important fields ofscience and ecotechnologies. The ecotechnology concept of the Honda Foundation that leads tothe implementation of technologies for sustainable development is very important in the 21stCentury. In this lecture, I would like to suggest that the success rate of eco-engineering isgreatly increased by connecting it to science pursued on the atomic and molecular level. Inturn, pursuit of ecotechnological goals has led to some of the most innovative science. (Fig 1)

Fig 132

Fig 2 Major Applications of Surfaces
Surfaces have many applications that impact our daily lives (Fig 2). Of these many
applications I chose catalysis and biointerfaces as the focus of my investigations over thedecades. This lecture deals with catalysis and, by necessity, nanomaterials because mostcatalysts are nanoparticles. I shall attempt to explain what catalysis is and why it is playing
such an important role in human life, including the ecotechnologies developed by Honda
Motor Co., Ltd. I will also explain how a combination of developments of experimental studies
and instrumentation led to an understanding of this phenomenon at the molecular level,
which in turn propelled catalysis to the frontier of science and technologies in broad fields ofhuman enterprise.

Evolution and achievements of Surface Science
What are surfaces? Figs 3a, 3b, and 3c show three types of surfaces. Fig 3a shows externalsurfaces ranging from single crystals (flat, stepped and kinked platinum surfaces) to the greenleaf.

Fig 3a External Surfaces

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Fig 3b Nanoparticle Surfaces

Fig 3c Internal Surfaces
Fig 3b shows nanoparticle surfaces that can be catalysts and also provide the orderedtransistor components in the integrated circuit elements of a computer. Fig 3c shows internalsurfaces of solids full of micropores or mezopores, such as the structures of the human bone ordevices that adsorb large amounts of gases or fluids. The study of modern surface sciencebegan with the discovery of the transistor, an amplifier device to be substituted for the radio
tube, and through the practice of space sciences. As transistors were made smaller andsmaller, they became faster and faster as the transmission of electrons became more rapid.
This gave rise to the technology quest of ever larger surface to volume ratios. Using the34ultrahigh vacuum technology developed by space sciences, device surfaces could be studied
free of impurities to determine and control their properties on the atomic scale.

Fig 4 Evolution of Surface ScienceFig 4 shows the surface science evolution in the 1965-1985 periods. The techniques to study
surfaces were electron, ion and molecule scattering, from clean surfaces of metals andsemiconductors. These studies uncovered the structure and bonding of surface atoms andmolecules, and the thermodynamics and dynamics of their adsorption, energy transfer andmobility that leads to surface chemical reactions.
However, the most important surface phenomena that are part of our everyday lives occur athigh pressures and liquid interfaces, and not in vacuum, which was the focus of the earlysurface science studies. In order to understand the molecular surface properties that play key
roles in corrosion, energy conversion, biointerfaces, environmental chemistry, friction andlubrication I spent the next 25 years developing techniques that could be utilized to study themolecular properties of surfaces at the buried solid-gas and solid-liquid interfaces (Fig 4).
Since I wanted to understand catalytic reactions on surfaces I had to extend my studies tonanomaterials in the 1990s, since most catalysts are nanoparticles.

35

Fig 5 In-situ techniques for molecular studies of high-pressure gas and liquid interfaces
The techniques I utilized in Berkeley, some of which were developed there, are shown in Fig 5,and I shall show their applications in molecular studies later.
I would like to introduce briefly some of the ecotechnologies that use surfaces almostexclusively. These include the catalytic converter on automobiles (Fig 6a) that is responsible
for removal of pollutants in urban areas like the Los Angeles basin (Fig 6b).

Fig 6a Three-way Catalyst (TWC) DesignFig 6b Emission from Automobiles in Los Angeles

Energy efficiency through reaction selectivity, commonly called “clean manufacturing” or“green chemistry,” means chemistry that yields only the desired molecule without any waste
by-products.

36

Examples include the production of high-octane gasoline (Fig 7a), isotactic polymerization (Fig7b), and synthetic fuel production from synthetic gas, CO and H2 (Fig 7c). Biointerfaces
produced via implant technologies (Fig 7d) is a rapidly growing area of biotechnology that is
responsible for the steadily growing life expectancy of humans.

Fig 7a Reforming with Pt. catalysts

Fig 7b Tacticity of Polypropylene37Fig 7c Fuels and Chemicals

Fig 7d Biointerfaces and Medical Devices

Approaches to nanoparticle catalyst
Let me turn to catalysis, which has been the focus of most of my studies past and present.
Catalysts are nanoparticles usually categorized into three distinct classifications: enzyme,homogeneous and heterogeneous. Examples in Fig 8 show that sizewise, these nanoparticles
are in the 1-8 nanometer range.

38Fig 8 Catalysts are Nanoparticles
In attempting to move from single crystals surfaces to nanoparticles (NPs) for utilization asheterogeneous catalysts (Fig 9a), our early efforts to synthesize them following thenanolithography technology practiced in the microelectronic industry did not succeed. The
smallest nanofeatures (dots, rods) we could produce were 25 nm, much larger than theparticle sizes of catalysts which are in the 1-10 nm range (Fig 9b).

Fig 9a Evolution of the Model Catalyst System39

Fig 9b Technically and Biologically Important Length Scales

We then turned to colloid science technologies, which are shown in Figs 10a, 10b, 10c, 10d,and 10e. This proved very successful. The metal nanoparticles are capped by an organic
surfactant or polymer that prevents their aggregation and permits their storage. The porous
nature of these caps allows molecular penetration and reactions on the metal surface. A cap
can also be removed to obtain clean NPs.

Fig 10a Control of Size and Shape of Pt Nanoparticles

40Fig 10b Pt and PdPt Alloy Nanocrystal Shape Control

Fig 10c TEM Images of RhxPd1-x Nanocrystals

41

Using inorganic oxide caps, which are also porous, the thermal stability of the metal NPs canbe greatly improved (Fig 10d) to overcome the low melting points associated with the small
size NPs (Fig 10e).

Fig 10d The Size Effect on the Melting Point of gold

Fig 10e Pt@SiO2 core shell structures of NPs with increased thermal stability

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Catalytic selectivity of metal nanoparticles
In the 20th Century much of catalysis science focused on understanding reactions that formed
one product; ammonia synthesis, ethylene hydrogenation, carbon monoxide oxidation. In the21st Century the focus is on catalytic selectivity; how to make only one molecule out of several
possible product molecules. (Fig 11).

Fig 11 Reaction product selectivity in Multipath catalytic reactions
We studied many multipath reactions and the conclusion of the studies is that size and shapeof metal nanoparticles control both catalytic reaction rates and selectivities.
We show a few examples of this finding (Figs 12a, 12b, 12c, 12d, and 12e). Clearly, the sizeand shape of the nanoparticles control the product distribution.

Fig 12a Effect of Pt Particle Size on Selectivity in Hydrocarbon Conversion Reactions:
Cyclohexene Hydrogenation/Dehydrogenation

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Fig 12b Pyrrole Hydrogenation over Pt NPs: Effect of Particle Size

Fig 12c Catalytic Furfural Chemistry over Pt NPs. Effects of Particle Size

44

Fig 12d Benzene Hydrogenation over Platinum Single Crystals and Different Shapes of NPs

Fig 12e Selective rearrangements of Methylcyclopentane in the presence of hydrogenon platinum nanoparticles of 6 nm Size and different shapes

45

The process of this control of product distribution by using selected NP sizes and shapes, wecall nanocatalysis (Fig 13)

Fig 13The question is why this is happening and why it was not utilized for the selective productionof molecules earlier. This brings to focus the flaw of catalytic studies in the past.
Catalysts were usually studied before-use and after-reaction. The lack of instruments andexperimental techniques to study the working catalyst while the catalytic reaction is inprogress was the reason for focusing on prenatal and postmortem studies.
The many techniques that are presently available to elucidate the structural and chemical
dynamics of the catalytic process. Below we show how the new techniques identify themolecular factors that control catalytic selectivity.

46

Sum Frequency Generation (SFG) Vibrational Spectroscopy
The unique surface sensitivity of SFG permits detection of reaction intermediates in catalytic
surface reactions (Figs 14a, 14b, 14c, 14d, 14e and 14f).

Fig 14a Sum Frequency Generation in situ Surface-Specific Vibrational Spectroscopy

Fig 14b and 14c Reaction intermediates during ethylene hydrogenationand cyclohexene hydrogenation and dehydrogenation
on platinum surfaces

47

Fig 14d Reaction intermediates during acrolein hydrogenation over Pt.
temperature dependence.

Fig 14e Reaction intermediates during crotonaldehyde Hydrogenation on Pt.

48

Fig 14f Reaction Intermediates during furan hydrogenation over Pt (111)single crystal and 10 nm size Pt nanoparticle

Surface composition detected under reaction conditions by ambient pressure X-ray
photoelectron spectroscopy

Fig 15a Ambient-pressure X-ray photo- Electron spectroscopy techniques (XPS)

Bimetallic nanoparticles undergo surface composition change driven by changing chemical(oxidizing and reducing environment) (Figs 15a, 15b and 15c)49

Fig 15b Core-Shell Structure Probed by Synchrotron XPS.
Surface segregation of Rhodium in Rh0.5Pd0.5 and palladium in
Pd0.5Pt0.5 in vacuum.

Fig 15c Restructuring of Rh0.5Pd0.5 nanoparticles during reactions
with oxidizing NO and reducing CO50

High Pressure Scanning Tunneling Microscopy Detects Adsorbate Mobility andAdsorbate-Induced Restructuring of Metal Surfaces

Fig 16a Scanning tunneling microscopy working under high-pressure conditions

Fig 16b High-pressure STM reaction studies:
The role of surface mobility under reaction conditions.

51

Fig 16c Blocking of adsorbate (C2H3 H) Mobility by CO poisons catalytic
reaction of Rh and Pt

Fig 16d Surface structure of Pt (557) and Pt (332) stepped crystal surfaces.

52

Fig 16e Pressure-dependent CO coverage and clustering of platinum atoms
at high coverage of CO

Fig 16f Reversible CO-induced Restructuring of stepped platinum surface

53

There are several molecular factors that control catalytic selectivity, which could be detected bytechniques that monitor the catalyst surfaces under reaction conditions (Fig 17). In addition,
there are two more important molecular factors that could be identified in catalytic reactions.

Fig 17 Molecular factors that control catalytic selectivity at surfaces

Change of Metal Oxidation State with Decreasing Size of Metal Nanoparticles which alsoPermits Heterogenizing Homogeneous Catalysts.
High oxidation state of small size nanoparticles permits their ability to carry out homogeneous
catalytic reactions using small (0.8 nm to 1.5 nm) size heterogeneous NP metal catalysts (Figs18a, 18b and 18c).

Fig 18a Size dependence of CO oxidation state activity(100 Torr of O2, 40 Torr of CO, and 443K) on rhodium nanoparticles.

54

Fig 18b Change of rhodium nanoparticle state oxidation state with NP size

Fig 18c Oxidation state changes with the size of Pt nanoparticles

55

Conversion of Homogeneous to Heterogeneous Catalysis using Dendrimers

Fig 19a Catalyst Preparation and Characterization

Fig 19b Solution-phase heterogeneous catalysis of homogeneous reaction withdendrimer encapsulated ~ 1 nm Pt40 nanoparticles supported on SBA-1556

Fig 19c Heterogenization of homogeneous reactions (Electrophilic reactions)Fig 19d Heterogenization of homogeneous reactions (Hydroformylation and Decarbonylation)

57

Fig 19e X-Ray Absorption Spectroscopy (XAS): What we measure?

Fig 19f The role of the coordination number and oxidation state during
heterogenizing homogeneous reactions using metal cluster on
dendrimer supports.

58

Charge transport and catalysis at oxide-metal interfaces

Fig 20a Strong Metal-Support Interaction (SMSI) EffectHydrogen and carbon monoxide catalytic oxidation generates a steady electron flow acrossplatinum (or other metals)/titanium oxide (or other oxides) Schottky diode. The thin metal
film (~ 4nm) provides the hot electrons (> 1 eV) that render the oxide-metal interfaces activereaction sites (Figs. 20a, 20b, 20c, 20d and 20e).

Fig 20b Hot electron generation in metals

59Fig 20c Mean free path of hot electrons in metal surfaces

Fig 20d Hot electron generation by exothermic catalytic reactions

60

Fig 20e Chemicurrent and turnover rate measure during carbon
monoxide oxidation

Fig 21
Charge transport at oxide-metal interfaces lead to the formation of charged molecules and toacid-base catalysis (Fig 21).

61

〈MEMO〉■ This report can be viewed in the Honda Foundation’s website.
You may not use the proceedings for the purposes other than personal use without theexpress written consent of The Honda Foundation.

62

発行責任者
Editor in chief

原 田 洋 一Yoichi Harada

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Tel. 03-3274-5125

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MEMO