Dissolving Ag from Au-Ag alloy nanoboxes with H₂O₂: A method for both tailoring the optical properties and measuring the H ₂O₂ concentration

This article describes a method for generating Au-based nanocages with controlled wall thickness, porosity, and optical properties by dissolving Ag from Au-Ag alloy nanoboxes with H₂O₂. It involves two steps: (i) formation of Au-Ag alloy nanoboxes with some pure Ag left behind by titrating Ag nanocubes with aqueous HAuCl₄ and (ii) removal of Ag atoms from both the pure Ag remaining in the nanoboxes and the alloy walls via H₂O₂ etching. The optical properties of the resulting Au-Ag nanocages can be easily tailored by controlling the amount of H ₂O₂ added into the reaction system. Due to the changes to the optical spectra, the Au-Ag alloy nanoboxes can also be employed to detect H₂O₂ with a linear readout (R² = 0.99) in the range of concentration from 5 × 10^-2 M down to 5 × 10^-7 M.