Photoelectrochemistry with Ordered CdS Nanoparticle/Relay or Photosensitizer/Relay Dyads on DNA Scaffolds

摘要

Stepwise vectorial electron transfer from a photoexcited species to an electron acceptor cascade that displays a downhill potential gradient is the fundamental principle in the accomplishment of effective charge separation in natural photosynthesis. During the last three decades, extensive research efforts have been directed to adapt the principles of charge separation in the photosynthetic apparatus to artificial systems. Ingenious photosensitizer-electron acceptor chains in covalently linked molecular structures, supramolecular structures, or organized microenvironments have been reported as means to stimulate photoinduced vectorial electron transfer and to accomplish charge separation. The concept of vectorial electron transfer and enhanced charge separation was also adopted in semiconductor nanoparticle systems. Photogeneration of electron-hole pairs in core-shell nanoparticles or hybrid nanoparticles was reported to enhance charge separation by interparticle electron trans-fer. similarly, the assembly of relay/semiconductor nanoparticle systems on electrodes was reported to provide a means to trap the conduction-band electrons and thus enhance the generation of photocurrents by preventing the electron-hole recombination process at the nanoparticle surface.