Surface Ligand-Mediated Plasmon-Driven Photochemical Reactions.
Contrary to the general expectation that surface ligands reduce the reactivity of surfaces by blocking the active sites, we present experimental evidence that surface ligands can in fact increase reactivity and induce important reaction pathways in plasmon-driven surface photochemistry. The remarkable effect of surface ligands is demonstrated by comparing the photochemistry of p-aminothiophenol (PATP) on resonant plasmonic gold nanorods (AuNRs) in the presence of citrate, hexadecyltrimethylammonium bromide (CTAB), and no surface ligands under visible light irradiation. The use of AuNRs with citrate and no surface ligand results in the usual azo-coupling reaction. In contrast, CTAB-coated AuNRs oxidize PATP primarily to p-nitrothiophenol (PNTP). Strong correlation has been observed between the N-O and Au-Br vibration band intensities, suggesting that CTAB influences the reaction pathway through the Br-counterions that can minimize the electron-hole recombination rate by reacting with the hole and hence increasing the concentration of hot electrons that drive the oxidation reaction.
Department of Chemistry and Chemical Biology, and Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States.
Bijesh
B
Kafle
Department of Chemistry and Chemical Biology, and Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States.
Marisa
M
Poveda
Department of Chemistry and Chemical Biology, and Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States.
Terefe G
http://orcid.org/0000-0001-5978-6464
TG
Habteyes