Gold-based nanostructures for efficient NIR-II photothermal conversion: hybridizing nanoplates with solid/hollow nanospheres

Abstract

To develop high-efficiency near-infrared (NIR) gold (Au)-based photothermal nanomaterials, the architectures of two-dimensional nanoplates/nanosheets or nanoparticles with hollow interiors could be two favorable options to realize the red-shift of major plasmonic absorptions towards a longer wavelength. Herein, we report a feasible strategy to create Au-based hybrid nanostructures including the structural components of both nanoplates and hollow nanospheres via a stepwise seeded growth. Particularly, Pt/Ag doping is applied initially to modify the surface of Au nanoplates, promoting the island-like deposition of Ag nanoparticles, followed by the galvanic replacement reaction (GRR) to readily etch the newly-deposited Ag nanoparticles into hollow ones. UV-vis-NIR extinction spectra show that the integration of hollow nanospheres over the Au nanoplates effectively causes the red-shift of the major absorption peak from ∼850 nm to beyond 1100 nm. Arising from such a plasmonic advantage, the current Au-based “hollow sphere-on-plate” hybrid nanostructures are found to exhibit an improved photothermal conversion efficiency under 1064 nm laser irradiation. The current work offers a feasible way to fabricate niche noble-metal hybrid nanostructures and validate their promising use in NIR-II photothermal conversion, which could be potentially extended to other metallic nanostructures.