Plasmon sensitivity and enhanced catalytic performance of nanocomposites based on Au nanorods

Abstract

The optical properties and potential applications of metal nanostructures are mainly related to the unique surface plasmon resonance (SPR) effects that highly depend on the morphology, composition, assembly style and surrounding medium of metal nanostructures. Compared with monometallic nanoparticles, bimetallic composite nanostructures exhibit improved physicochemical properties. In this paper, the preparation and performance study of core–shell Au@Ag nanocuboids and open Au@Pd nanoframes were carried out based on Au nanorods with different aspect ratios. The co-reduction method was applied to control the deposition of Ag atoms on the surface of Au nanorods to obtain Au@Ag nanocuboids. The nanocuboids have flat surfaces and exhibit an adjustable SPR effect in a wide spectral region. Moreover, they show an ultra-sensitive response to the change of the surrounding medium. The refractive index sensitivity of the Au@Ag nanocuboids is better than that of the Au nanorods. Due to the rich edges and sharp corners, this Au@Ag nanocuboid structure can also be used as a hard template for further growth of highly active nanoframes. Then we controlled the deposition of Pd atoms on the surface, especially the edge parts, of Au@Ag nanocuboids. A new nanostructure of open Au@AgPd nanoframes was constructed after selectively etching the Ag shell. These open nanoframes not only show strong SPR properties similar to Au nanorods, but also exhibit excellent catalytic performance in the electrocatalytic reaction of ethanol. This work provides an idea for designing efficient sensors and nanocatalysts.