Interfacial Construction of Plasmonic Nanostructures for the Utilization of the Plasmon-Excited Electrons and Holes.

Surface plasmons (SPs) are able to promote chemical reactions through the participation of the energetic charge carriers produced following plasmons decay. Using p-aminothiophenol (PATP) as a probe molecule, we used surface-enhanced Raman spectroscopy to follow the progress of its transformation, in situ, to investigate systematically the role of hot electrons and holes. The energetic carrier mediated PATP oxidation was found to occur even in the absence of oxygen, and was greatly influenced by the interface region near the gold surface. The observed reaction, which occurred efficiently on Au@TiO nanostructures, did not happen on bare gold nanoparticles (NPs) or core-shell nanostructures when a silicon oxide layer blocked access to the gold. Moreover, the product of the PATP oxidation with oxygen on Au@TiO nanostructures differed from what was obtained without oxygen, suggesting that the mechanism through which "hot holes" mediated the oxidation reaction was different from that operating with oxygen activated by hot electrons.