Solar Energy Conversion and Environmental Remediation Using Inorganic SemiconductorLiquid Interfaces: The Road Traveled and

ABSTRACT: Unlike their solid-state counterparts, semiconductorliquid junctions are versatile in that the incident solar energy can be stored in the form of chemical fuels. Another attractive application is the use of irradiated oxide semiconductor-coated surfaces for self-cleaning and antifogging. The theme of this history-tinged Guest Commentary centers on the question of what has been accomplished in the above “photoelectrochemical ” schemes over the 35 year time frame from 1975 to 2010. Progress in this field was aided by the infusion of new concepts and contributions from the materials chemistry and physics communities. A related aspect of discussion is how the active semiconductor material has evolved both chemically andmorphologically in these applications. It is shown that despite impressive research advances, only a handful of the above concepts (e.g., dye-sensitized solar photon conversion and self-cleaning and antifogging surfaces) have made the successful transition from the laboratory to the marketplace. Alphonse Lamartine, the French poet and writer, said thathistory teaches everything including the future. In the words of the English writer, G. K. Chesterton, “We can be almost certain of being wrong about the future, if we are wrong about the past.” Therefore, it seems profitable to take a look at where we started and how far we have come in the field of photoelectrochemistry and solar energy conversion. The discussion below pertains very largely to inorganic semiconductors, and solid-state solar device