Synthesis of porous Ag–Ag2S@Ag–Au hybrid nanostructures with broadband absorption properties and their photothermal conversion application

Abstract

Hybrid nanostructures composed of a plasmonic noble metal and a semiconductor have been studied intensively because of their unusual properties and wide range of potential applications. However, preparing these hybrid nanostructures with a precisely controlled shape, composition, heterostructure, and internal structure remains a challenge. Here, we describe a method for synthesizing new metal–semiconductor@bimetal hybrid nanostructures. Specifically, Ag–Ag2S nanoplates were first prepared by site-controlled sulfidation, and these nanoplates were then used as seeds to synthesize Ag–Ag2S@Ag–Au hybrid nanostructures with unique porous architectures through seed-mediated growth and a galvanic replacement reaction. The composition of the ternary alloy combined with the unique porous structure of the hybrid nanostructures resulted in excellent broadband absorption in the UV–Vis–NIR region (300–1100 nm), and hence a black color, without an additional post-treatment process. When used as photothermal conversion materials, the hybrid nanostructures showed good photothermal conversion activity, with a maximum efficiency of 76.1% under irradiation with an 808 nm near-infrared laser. A mechanism for the high photothermal conversion activity is proposed on the basis of experimental and simulation results.