Plasma Electrochemical Synthesis of Composition Tunable Au–Ag Bimetallic Nanoparticles

Abstract

The synthesis of bimetallic nanoparticles (BNPs) with a controlled structure and composition is crucial for advancing their applications in catalysis, biosensing, and nanoenergy. This study introduces a surfactant- and ligand-free one-pot synthesis of Au–Ag BNPs in aqueous solutions using pulsed plasma-driven solution electrochemistry (PDSE). PDSE-enabled structural modulation of Au–Ag BNPs was achieved simply by tuning a precursor solution pH, with acidic conditions favoring Au–Ag core–shell configurations, neutral conditions promoting homogeneous alloys, and basic conditions enabling Ag–Au core–shell structure formation. Additionally, we demonstrated composition control through the introduction of oxygen in the feed gas and voltage pulse width modulation, leveraging reactive oxygen species to selectively oxidize Ag, thereby tuning the Ag and Au ratios in the synthesized BNPs. Our one-pot and fast synthesis approach eliminates the need for surfactants/ligands and reducing agents, making it a nontoxic and cost-effective alternative to traditional wet-chemical synthesis methods. Findings from our contribution can offer new insights into the fundamental mechanisms of BNP formation in PDSE and pave the way for scalable and tunable BNPs synthesis for diverse technological applications.