Solid–Solution–Solid (SSS) phase transitions for Gram-Scale and High-Throughput synthesis of noble metal nanoparticles in deep eutectic solvents

Abstract

Modern colloidal chemistry has enabled the controlled synthesis of various noble metal nanoparticles with unique physical and chemical properties. However, solution-based synthesis still suffers from limited productivity, particularly in industrial applications. We have developed the gram-scale synthesis of gold nanoparticles (AuNPs) using a polymerizable deep eutectic solvent (DES) via solid–solution–solid phase transitions. The DES plays two important roles, as a designer solvent. First, the solvating power of the DES allows the precursors to dissolve easily, even at high concentrations. Second, the concomitant polymerization of the DES with the synthesis of highly concentrated AuNPs and their consequent fixation in the polymer matrix is crucial for their stabilization. This rapid one-pot synthesis provides the highest productivity, among the other previously reported gram-scale syntheses of AuNPs. The procedure can be easily extended to conduct multiple reactions in a high-throughput manner. The chemical and physical properties and synthesis mechanisms of the AuNPs are thoroughly investigated. The synthesis of other noble metal (Pd, Ag, Au) nanoparticles, which are mono- and bimetallic, has also been demonstrated using the DES. As a practical application, a large-area transparent display is demonstrated using AuNPs synthesized in the DES, implying the scope for further industrial applications.