Rational Tuning of Metal–Semiconductor Nano-Icosapods for Plasmon-Induced Photodetection

Plasmonic metal–semiconductor heterostructures with well-defined morphologies and spatial architectures have emerged as promising materials for wide applications in photocatalysis and optoelectronics. However, the synthesis of such structures with high quality and high yield remains a great challenge due to the incompatibility between the two materials. Herein, we report an optimized approach for the controlled preparation of branched Ag-CdS icosapods, which possess 20 CdS arms with an ordered spatial arrangement on the Ag cores. Moreover, the length, diameter, and thickness of the CdS arms on the Ag nanoparticles can be precisely tuned by the synthetic conditions, leading to Ag-CdS icosapods with tunable absorption properties. Furthermore, more complex hierarchical nanostructures can be achieved by the secondary growth of nanoplate arrays on the CdS arms. As a proof of concept, a phototransistor based on the self-assembled monolayer film of Ag-CdS icosapods shows a stable photoresponse and quite a fast switching performance under optical illumination of 540 nm without excitation of the CdS, which originates from the generation and transfer of plasmon-induced hot carriers in the Ag-CdS icosapods under an applied bias. This work offers a reproducible approach to finely tuning metal–semiconductor heterostructures with desirable architectures and paves the way for more deeply understanding their structure–property correlation.