AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP26
Active Sites of Photocatalyst for Water Decomposition of RuO@sub 2@-dispersed p-block Metal Oxides Involving In@super 3+@, Ga@super 3+@, Sn@super 4+@ and Ge@super 4+@ with d@super 10@ Configuration

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: J. Sato, Nagaoka University of Technology, Japan
Authors: J. Sato, Nagaoka University of Technology, Japan
H. Nishiyama, Nagaoka University of Technology, Japan
N. Saito, Nagaoka University of Technology, Japan
K. Ikarashi, Nagaoka University of Technology, Japan
Y. Inoue, Nagaoka University of Technology, Japan
Correspondent: Click to Email
The development of solid photocatalysts to produce hydrogen from water has been among important issues. The photocatalysts discovered so far have been the transition metal oxides with d@super 0@ configuration. In aiming at finding a new photocatalyst group, we have focused on the p-block metal oxides with d@super 10@ configuration.@footnote 1@ In the present study, MIn@sub 2@O@sub 4@, MGa@sub 2@O@sub 4@, M@sub 2@SnO@sub 4@ (M = Mg, Ca, Sr, Ba ), and Zn@sub 2@GeO@sub 4@ were employed, and the effects of M on the photocatalytic activities were examined. For photocatalytic decomposition of water, RuO@sub 2@ were loaded on p-block metal oxides by an impregnation method. MIn@sub 2@O@sub 4@ (M= Ca,Sr) have pentagonal-prism-like tunnel structures with two distorted InO@sub 6@ octahedra each. For M = Ca and Sr, hydrogen and oxygen were stably evolved in repeated run under Xe lamp light illumination, whereas little activity was observed for M= Ba. The activity of M@sub 2@SnO@sub 4@ (M= Ca, Sr, Ba) was remarkably large for M= Ca and M= Sr, but negligible for M= Ba. The SnO@sub 6@ octahedra of M= Ca and M=Sr were distorted, whereas those of M= Ba were normal, indicating the contribution of the deformed octahedra to photocatalysis. In MGa@sub 2@O@sub 4@ (M=Mg, Sr, Ba), the activity was observed for M=Sr and M=Ba, but not for M=Mg, for which there existed correlation between photocatalytic activity and distorted metal-oxygen units. The present study clearly demonstrates that the distorted metal-oxygen units play an important role in the photocatalysis, which is possibly related to the efficiency of photoexcited charge formation. The p-block metal oxides with d@super 10@ configuration is concluded to form a new photocatalyst group for water decomposition. @FootnoteText@ @footnote 1@ J. Sato, N. Saito, H. Nishiyama, and Y. Inoue, J. Phys. Chem., 105, 6061 (2001).