Formation of Mixed Bimetallic Nanoparticles of Immiscible Metals through Plasma-Induced Reduction of Precursors in Solutions: A Case Study of Ag–Pt Alloy Nanoparticles

Abstract

Bimetallic alloy nanomaterials exhibit promising properties in various applications. The synthesis of these nanomaterials is often challenging due to the immiscibility of the metals forming the alloy. To overcome this issue, complex synthetic strategies, relying on difficult-to-control reduction conditions, have been utilized, showing that rapid reduction and quenching are required to kinetically trap immiscible metal atoms in single nanoparticles. In this study, we demonstrate a simpler synthetic strategy to form well-mixed bimetallic nanoparticles of immiscible metals. We exploit the interactions between pulsed plasma and solutions charged with metal precursor salts to rapidly form metal atoms. We demonstrate that the minimal requirements for the formation of alloys include the following: (i) the metal precursor reduction rates are high enough to allow the kinetic trapping of alloy nanoparticles, (ii) the reduction rates are similar for the respective metal precursors, ensuring a consistent mixing during the growth process, and (iii) the nucleation process is controlled to avoid the “burst nucleation” which takes place when the local concentrations of reduced metal atom monomers exceed a critical threshold.