# Nanoelectrum across the Visible Spectrum: Tailored Ag–Au Alloy Nanoparticles with Glutathione-Enhanced Stability

## TL;DR

This paper introduces new methods to create stable Ag–Au alloy nanoparticles with tunable properties for applications like catalysis and sensing.

## Contribution

The first use of glutathione as a capping agent to stabilize hollow Ag–Au nanoparticles is presented.

## Key findings

- Surfactant-assisted and surfactant-free methods enable controlled synthesis of hollow and solid Ag–Au NPs.
- Cl– ions and reducing agents synergistically control galvanic replacement and silver loss.
- Glutathione enhances the structural stability and colloidal longevity of hollow Ag–Au NPs.

## Abstract

Nanoelectrum (Ag–Au
alloy nanoparticles, Ag–Au
NPs)
combines the unique nanoscale characteristics of silver and gold into
a single bimetallic system exhibiting synergistic properties distinct
from those of individual metals. Despite their significant potential
and enhanced performance in applications such as catalysis and surface-enhanced
Raman spectroscopy (SERS), the use of Ag–Au NPs remains limited
due to challenges in achieving controlled and reproducible synthesis.
Here, we present surfactant-assisted and surfactant-free approaches
for the synthesis of both hollow and solid Ag–Au NPs from AgNP
seeds across a wide range of Ag to Au ratios and AgNP sizes. We highlight
the synergistic role of Cl– ions and reducing agents
in controlling the extent of galvanic replacement and minimizing the
loss of Ag. In addition, we demonstrate for the first time the use
of glutathione (GSH) as a postsynthetic capping agent to preserve
structural integrity and ensure long-term colloidal stability of hollow
Ag–Au NPs. These findings provide a much needed versatile and
practical framework for fine-tuning the size, shape, and composition
of Ag–Au NPs, facilitating the rational design of plasmonic
bimetallic systems across the visible spectrum.