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

Plasmonic metal-semiconductor heterostructureswith well-definedmorphologies and spatial architectures have emerged as promising materialsfor wide applications in photocatalysis and optoelectronics. However,the synthesis of such structures with high quality and high yieldremains a great challenge due to the incompatibility between the twomaterials. Herein, we report an optimized approach for the controlledpreparation of branched Ag-CdS icosapods, which possess 20 CdS armswith an ordered spatial arrangement on the Ag cores. Moreover, thelength, diameter, and thickness of the CdS arms on the Ag nanoparticlescan be precisely tuned by the synthetic conditions, leading to Ag-CdSicosapods with tunable absorption properties. Furthermore, more complexhierarchical nanostructures can be achieved by the secondary growthof nanoplate arrays on the CdS arms. As a proof of concept, a phototransistorbased on the self-assembled monolayer film of Ag-CdS icosapods showsa stable photoresponse and quite a fast switching performance underoptical illumination of 540 nm without excitation of the CdS, whichoriginates from the generation and transfer of plasmon-induced hotcarriers in the Ag-CdS icosapods under an applied bias. This workoffers a reproducible approach to finely tuning metal-semiconductorheterostructures with desirable architectures and paves the way formore deeply understanding their structure-property correlation.