Dissolving Ag from Au-Ag Alloy Nanoboxes with H(2)O(2): A Method for Both Tailoring the Optical Properties and Measuring the H(2)O(2) 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 H(2)O(2). It involves two steps: i) formation of Au-Ag alloy nanoboxes with some pure Ag left behind by titrating Ag nanocubes with aqueous HAuCl(4); and ii) removal of Ag atoms from both the pure Ag remaining in the nanoboxes and the alloy walls via H(2)O(2) etching. The optical properties of the resultant Au-Ag nanocages can be easily tailored by controlling the amount of H(2)O(2) added into the reaction system. Due to the changes to the optical spectra, the Au-Ag alloy nanoboxes can also be employed to detect H(2)O(2) with a more or less linear readout in the range of concentration from 5×10(-2) M down to 5×10(-7) M.