Page 84 - Multifunctional Photocatalytic Materials for Energy

Energy band engineering of metal oxide for enhanced visible light absorption 73

that accept the excited electrons from VB, thus avoiding the reduction of Cu. More
emphasis should be put on these materials from synthesis techniques, to fundamen-
tal understanding, to device fabrication. On the other hand, the photocurrents of cur-
rently studied photoanode metal oxides like BVO, hematite, and TiO 2 are still much
lower than those of semiconductor photocathodes and also their theoretical maximum.
Novel engineering techniques and tools on the geometry, surface chemistry, and phys-
ical understanding of the energy band and charge transfer need to be further explored.

Acknowledgments

The authors gratefully acknowledge support from the United States Department of the Army
and the United States Army Material Command. J. Li also acknowledges support from the
United States Army Research Laboratory Senior Research Fellowship Program, which is ad-
ministered by the Oak Ridge Associated Universities.

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