Synthesis of Dumbbell-Like Gold-Metal Sulfide Core-Shell Nanorods with Largely Enhanced Transverse Plasmon Resonance in Visible Region and Efficiently Improved Photocatalytic Activity

The metallic nanostructures with unique properties of tunable plasmon resonance and large field enhancement have been cooperated with semiconductor to construct hetero-nanostructures for various applications. Herein, a general and facile approach to synthesize uniform dumbbell-like gold-sulfide core-shell hetero-nanostructures is reported. The transformation from Au nanorods (NRs) to dumbbell-like Au NRs and coating of metal sulfide shells (including Bi2S3, CdS, CuxS, and ZnS) are achieved in a one-pot reaction. Due to the reshaping of Au core and the deposition of sulfide shell, the plasmon resonances of Au NRs are highly enhanced, especially the about 2 times enhancement for the visible transverse plasmon resonance compared with the initial Au NRs. Owing to the highly enhanced visible light absorption and strong local electric field, we find the photocatalytic activity of dumbbell-like Au-Bi2S3 NRs is largely enhanced compared with pure Bi2S3 and normal Au-Bi2S3 NRs by testing the photodegradation rate of Rhodamine B (RhB). Moreover, the second-layer sulfide can be coated and the double-shell Au-Bi2S3-CdS heteronanostructures show further improved photodegradation rate, especially about 2 times than that of Degussa P25 TiO2 (P25) ascribing to the optimum band arrangement and then the prolonged lifetime of photo-generated carriers.