A thermal evaporator for aerosol core-shell nanoparticle synthesis

Segregated bimetallic nanoparticles like core-shell nanoparticles are of interest in various fields including biomedicine, catalysis, and optoelectronics. Aerosol technology is an optimal platform to control nanoparticle size, structure, and composition, which are some of the most important parameters tuning the material performance for the intended applications. Here, we develop a novel evaporator design to coat core particles on-line with a shell directly in the gas phase. The evaporator employs a local heater that decouples heating the evaporating material from the aerosol particles to limit core-shell alloying. We characterize the system by evaporating Zn onto core particles of Au, Sn, and Bi and demonstrate the core-shell particle formation with controllable shell thickness in each material system. We discuss simple models to explain the observed growth process inside the evaporator and the resulting shell formation.

Automated summary

Segregated bimetallic nanoparticles, such as core-shell nanoparticles, have attracted widespread interest in various fields like biomedicine, catalysis, and optoelectronics. Aerosol technology provides an optimal platform for controlling the size, structure, and composition of nanoparticles, which are crucial parameters for tuning the material performance for specific applications. In this study, researchers developed a novel evaporator design that allows on-line coating of core particles with a shell directly in the gas phase. By utilizing a local heater, the researchers were able to decouple the heating process of the evaporating material from the aerosol particles, thereby limiting core-shell alloying. The resulting core-shell particle formation with controllable shell thickness was demonstrated using evaporation of zinc onto core particles of gold, tin, and bismuth. Simple models were also discussed to explain the observed growth process inside the evaporator and the formation of the shell.