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[资源] 2011新书光催化Topics in Current Chemistry：Photocatalysis

Photocatalysis

Preface
Solar energy is the only renewable and carbon neutral energy source of sufﬁcient
scale to replace fossil fuels. Direct conversion of this energy into clean fuels is one
of the most important scientiﬁc challenges of the 21st century. In this context, both hydrogen production from solar water splitting and carbon dioxide conversion to organics are obviously attractive, being potentially convenient and clean methods
to store solar energy in energy rich molecules which can be employed as virtually
inexhaustible fuel sources.
Although the realization of a molecular level system mimicking natural photo-
synthesis for the production of solar fuels is certainly fascinating from a fundamen-
tal viewpoint, the achievement of efﬁcient water splitting has so far been limited by
a small driving force and kinetic complications arising from the need to realize a
multiple proton coupled charge transfer, which is necessary to simultaneously
overcome the demanding kinetics of water oxidation and reduction. For these
reasons either sacriﬁcial hole or electron scavengers have been coupled to most
molecular level charge separators.
Since the experiment of Fujishima and Honda in 1972, the direct use of semi-
conductor photoelectrodes or nanoparticles, have appeared to be an alternative way
for achieving photoinduced water splitting, thanks to the possibility of obtaining,
with a practically unitary quantum yield, highly energetic charge carriers that can
induce the required electrochemical reactions at the solid/electrolyte interface.
Photoanodes based on n-type metal oxides like TiO2,WO3 and Fe2O3 have been
intensely studied, since, at appropriate pH, they couple ease of fabrication, high
chemical stability in aqueous solution under evolving oxygen conditions, and
reasonably high incident light to current generation when operated in a photoelec-
trochemical cell.
On the other hand, the development of molecular systems and interfaces for the
conversion of carbon dioxide into energy rich molecules represents an important
technological and environmental challenge due to the abundance of CO2 in the
biosphere that contributes signiﬁcantly to the greenhouse effect. In this context
important research activities are directed towards the preparation of photocatalysts
containing a photosensitizer unit, which initiates photochemical one-electron
ixtransfer events, and a catalyst which stores reducing equivalents to achieve multi-
electron reduction of CO2.
Finally, Photocatalysis is particularly relevant in order to realize chemical trans-
formations of synthetic interest with a minimal environmental impact. In fact, pho-
tochemical reactions require milder conditions than thermal processes and may
allow for the conception of short and efﬁcient reaction sequences, minimizing side
processes.
The research discussed within the framework of this volume aims to identify and
provide solutions to these problems through the application of solar energy conver-
sion schemes which involve the use of regenerative photoelectrochemical, photo-
electrolytic or photoelectrosynthetic cells in which solar energy can be stored into
chemical fuels and in the development of photocatalytic processes for selective
photooxidation of organic compounds.
Carlo Alberto Bignozzi
Stefano Caramor[ Last edited by htj5170 on 2011-9-22 at 21:47 ]

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