Stability of Fluorescence Emission from Gold Nanoclusters and Photocatalyt-ic Redox on Surface
The fluorescent emission and the photocatalytic activity of gold nanoclusters(AuNCs)are important properties of AuNCs.Here,we synthesized water-soluble,captopril(Capt)and glu-tathione(GSH)covered Au25(Capt)18 and Au15(GSH)13 nanoclusters and investigated their fluorescence stabilities which are correlated with the photo-redox of their surface.It was ob-served that Au25(Capt)18 exhibited a decay in its two-photon fluorescence emission induced by surface oxidation upon irradiation of femtosecond near-infrared laser(810 nm,300 mW)in the presence of oxygen(O2).On the other hand,the two-photon fluorescence from Au15(GSH)13 was stable upon the same excitation.The different stabilities of the fluores-cence of the two AuNCs were attributed to their different band gaps.This interpretation was confirmed by one-photon excitation with photon energy beyond the band gaps of the two AuNCs.Using experiments with the addition of several agents,the photocatalytic redox ac-tivities of gold atoms on the surface of Au25(Capt)18 were understood and tuned.
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