This project is in the general area of analytical and surface chemistry and in the subfield of photoelectrochemistry. This research activity continues and broadens investigations of electrochemical and photoelectrochemical reactions and the characterization of semiconductor electrodes that were initiated during the tenure of NSF grant CHE-8304666. This research is providing fundamental insights into the nature of the semiconductor/liquid junction and the chemical and photochemical reactions that can be carried out at such junctions. These interfacial systems are of direct significance to applications such as solar energy conversion to electricity and useful chemical products, photoetching of semiconductors, analytical sensors, and nonlinear optical devices. This research stresses new approaches to the characterization of the semiconductor interface by scanning tunneling microscopy and ellipsometry, and the study of size and doping effects in particulate semiconductors. Investigations of the design and application of "integrated chemical systems" having tailored arrangements of semiconductor, catalyst, sensitizer, and redox couples within a support, with structural organization at the micrometer level, to promote desired photoreactions will be pursued. This broad research activity provides new, fundamental knowledge of photoinduced charge transfer processes at semiconductor interfaces and the effects of structure and ordered chemical composition on the efficiency of these processes. Additionally, these studies should give rise to new photoelectrochemical devices and enhanced technologies for the processing of semiconductor materials.
