inorganic chemistry

discussion is still needed to establish a method to clarify the syn-
ergetic effect in photocatalysis.

VII. Concluding Remarks

When the author started the study on photocatalysis in 1981,
there appeared to be no laboratories doing research work only
on photocatalysis, that is, photocatalysis studies were preformed
in laboratories in the field of catalysis, electrochemistry, photo-
chemistry, materials chemistry, etc. This means that results of
those studies have been discussed, presumably, on the basis of
different concepts, analytical methods or understanding
depending on the fields, and this might give rise to
misunderstandings, misconceptions, or speculations, some of
which are described in this review. It is time now to fix the field
of “photocatalysis” having common unified understandings. It
would be the author’s great pleasure if this review builds a
momentum for unified understandings of photocatalysis.

ACKNOWLEDGMENTS

This work was partly supported by Project to Create
Photocatalyst Industry for Recycling-oriented Society supported
by NEDO, New Energy and Industrial Technology Development
Organization and Grant-in-Aid for“Scientific Research (A) (Gen-
eral)”from the Ministry of Education, Culture, Sports, Science
and Technology (MEXT) of Japan.

REFERENCES

1. Fujishima, A.; Hashimoto, K.; Watanabe, T. In“TiO 2 Photocatalysis Fun-
   damentals and Applications”; Bkc, Inc.: Tokyo, 1999.


2. Hoffmann, M. R.; Martin, S. T.; Choi, W. Y.Chem. Rev.1995, 95 , 69.


3. (a) Fujishima, A.; Zhang, X. T.; Tryk, D. A.Surf. Sci. Rep.2008, 63 , 515.
   (b) Fujishima, A.; Zhang, X.; Tryk, D. A.Int. J. Hydrogen Energy2007,
   32 , 2664.


4. Ohtani, B.Chem. Lett.2008, 37 , 216.


5. Papers reporting activation energy of photocatalytic reactions in the
   period 2000–2004. Figures and compounds in square brackets and
   parentheses, respectively, show activation energy in the unit of kJ mol-1
   and substrate. (a)Vorontsov, A. V.; Stoyanova, I. V.; Kozlov, D. V.;
   Simagina, V. I.; Savinov, E. N.J. Catal.2000, 189 , 360 [10.9 (acetone)].
   (b) Xu, Y. M. Chem. J. Chin. Univ. Chin. 2000, 21 , 1539 [4.2-4.6
   (acetophenone)]. (c) Su, W. Y.; Fu, X. Z.; Wei, K. M.Chem. J. Chin. Univ.

PHOTOCATALYSIS BY INORGANIC SOLID MATERIALS 425