Semiconductor photocatalysis using nanoparticlate TiO2 has proven to be a promising technology for use in photocatalytic reactions, in the cleanup of water, or as a photoactive material in nanocrystalline solar cells. We have found that a reconstructed surface of metal oxide nanoparticles differs from the bulk by the presence of a highly reactive under-coordinated surface. This can be viewed as a curse or as an opportunity. The under-coordinated surface metal atoms trap light-induced charges, but also exhibit high affinity for oxygen-containing ligands. As a result of this strong interaction, delocalized bands of metal oxide nanoparticles are electronically coupled to organic linkers, improving their optical properties in the visible region and photovoltaic response due to enhanced charge separation across the nanoparticle interface. In the same manner we use photoinduced charge separation in order to control and manipulate processes within living cells.

Argonne Physics Division Colloquium Schedule