Insulating plasmonic photothermal heat of Ag nanoparticles by a thin carbon shell

Abstract

Plasmonic photothermal effect of metal nanoparticles has been used for efficient cancer therapy and catalysis. Here, we show the insulation of Plasmonic photothermal heat generated in Ag nanoparticles by a thin carbon shell and their application for solar desalination of seawater. Ag, carbon and Ag with carbon shells (Ag@C) nanoparticles were synthesized by a hydrothermal method. The absorption of Ag@C core/shell nanoparticles almost covers the whole visible light spectrum from red to violet, which can be tuned by changing the thickness of the carbon shells and the size ratio of Ag cores to carbon shells. Ag@C core/shell nanoparticles with the size of 50 nm@18 nm exhibit a photothermal conversion efficiency 44% higher than carbon nanoparticles. Importantly, it is observed that carbon shells have excellent heat insulation property so that the temperature decay lifetime of Ag nanoparticles is enhanced by 49% after coating with a thin carbon shell of 18 nm. Ag@C nanoparticles supported by anodic aluminum oxide (AAO) templates exhibit a desalination rate 1000% higher than the direct evaporation of seawater under simulated solar irradiation and 220% higher than that of AAO templates supported carbon nanospheres.