Synthesis of Au-Ag bimetallic nanoparticles via plasma-driven solution electrochemistry with controllable structure and composition

Plasma-driven solution electrochemistry (PDSE) is a promising bottom-up approach for nanomaterial synthesis due to its simplicity and ability to minimize the use of harmful chemicals. The timescale of nanoparticle formation, including nucleation and growth, is much shorter than in conventional wet-chemical methods, enabling potentially scalable production.

Bimetallic nanoparticles, composed of two different metals, exhibit unique, synergistic properties—such as enhanced stability and catalytic activity—distinct from monometallic ones. PDSE has shown capability in synthesizing bimetallic nanoparticles, including immiscible metals (e.g., Ag-Pt). However, studies on structure-controlled synthesis (core-shell vs. alloy) and elemental composition tuning remain rare. Additionally, transport and co-reductions of metallic ions are not yet quantitatively studied.

We present a one-pot method to synthesize Ag-Au bimetallic nanoparticles with tunable structure and composition using a pulsed plasma jet on an HAuCl₄–AgF solution as an anode. Nanoparticles are formed through the reduction of the precursor and their composition was controlled by adding oxygen to the helium feed gas and changing the voltage pulse width. Structural tuning was achieved by modifying solution pH, leveraging different reduction potentials of gold complexes. We will report on the underpinning mechanisms of the processes and tuning ability providing insights into synthesizing versatile bimetallic nanoparticles for catalysis, plasmonics, biomedicine, and nanoenergetics.