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Name (Title):
Kohei Uosaki (Professor 1 , Principal Investigator 2 )
Affiliation:
1
Division of Chemistry, Graduate School of Science, Hokkaido University
2
MANA Satellite, NIMS
Address:
N10 W8, Kita-ku, Sapporo 060-0810, Japan
Email: uosaki@pcl.sci.hokudai.ac.jp
Home Page: http://pchem.sci.hokudai.ac.jp/
Presentation Title:
Atomic and Molecular Assemblies for Efficient Energy Conversion at Solid/Liquid Interfaces
Abstract:
Development of the efficient system for inter-conversion of light, chemical and electrical
energies is the one of the most important global issues in the 21st century. In natural systems, the
inter-conversion is achieved based on well ordered arrangement of organic and biological
molecules with various functions such as photon absorption, electron relay, and catalyst, i.e.,
enzyme. On the other hand, inorganic materials are mainly used for energy/materials conversion
in modern technology. The efficiency and durability of these systems are still needs to be
improved.
Here I would like to describe two examples of the construction of interfacial phases for highly
efficient energy/materials conversion at solid/liquid interfaces by arranging atoms and molecules
with atomic/molecular resolution.
1. Construction of photoenergy conversion interfaces by molecularly ordered modification of
semiconductor surfaces. Hydrogen is the most important clean fuels in the future and production
of hydrogen from water by solar energy is
required. Photoelectrochemical (PEC) and
photocatalytic decomposition of water has been
studied for long time. Most serious problem of
PEC production of hydrogen from water is that
while semiconductor electrodes with small
energy gap can absorb large fraction of solar
energy but unstable, those with large energy gap
are stable but can absorb only small fraction of
solar energy. This can be solved by using
semiconductor of small gap and separating the
reaction site from the surface. Figure 1 shows
that hydrogen evolution current flowed at more
positive potentials than the reversible potential at
a p-Si(111) electrode surface modified with
multi-viologen (molecular wire)-Pt nanoclusters
(HER catalyst)-layers under illumination. 1
2. Construction of catalytic interfaces by atomically ordered modification of metal surfaces with
foreign metals. Atomically arranged nano-composites were constructed first forming multinuclear
metal complex layers on a substrate followed by their thermal/electrochemical
decomposition. Remarkable increase of electrocatalytic activities for hydrogen evolution and
methanol oxidation reactions were obtained using Pt-Ru binuclear metal complexes as starting
materilas. 2
References:
[1] T. Masuda, K. Shimazu, and K Uosaki, J. Phys. Chem. C, 112, 29, 10923-10930 (2008).
[2] H. Uehara, Y. Okawa, Y. Sasaki and K. Uosaki, Chem. Lett., 38, 148-149 (2009).
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Oral Presentation 36
Figure 1. Photocurrent-voltage relations of p-Si(111)
electrode modified with various functional layers.