Unusual Circularly Polarized Photocatalytic Activity in Nanogapped Gold-Silver Chiroplasmonic Nanostructures

Gold-gap-silver nanostructures (GGS NSs) with interior nanobridged gaps are enantioselectively fabricated. Guided by L/D-cysteine, the GGS-L/D (L/D represents L/D-cysteine) NSs show reversed plasmon-induced circular dichroism (CD) signals in the visible region. It is found that the nanogap plays a key role in the plasmonic CD of GGS NSs and the chiroptical response can be tailored by adjusting the amount of cysteine. The anisotropy factor of GGS-L/D NSs with a 0.5 nm interior gap at 430 nm is as high as approximate to 0.01. The circularly polarized photocatalytic activity of GGS NSs is examined. It is shown that upon irradiation with left-circularly polarized light, the catalytic effi ciency of GGS-L NSs is 73-fold and 17-fold higher than that of Au nanoparticles (NPs) and Au@Ag core-shell NPs, respectively. Upon irradiation with right-circularly polarized light, the catalytic activity of GGS-D NSs is about 71 times and 17 times higher than that of Au NPs and Au@Ag core-shell NPs, respectively. These unique chiral NSs with high plasmonic response can be applied to enantioselective catalysis.