Mechanistic Study on the Bis(p-sulfonatophenyl)phenylphosphine Synthesis of Monometallic Pt Hollow Nanoboxes Using Ag*−Pt Core−Shell Nanocubes as Sacrificial Templates

We report herewith a simple and effective method for the preparation of anisotropic Ag*−Pt core−shell nanocubes and Pt nanoboxes. The core−shell nanocubes were first synthesized by the coreduction of Ag⁺ and PtCl₆^2- and then treated in a bis-(p-sulfonatophenyl)-phenylphosphine (BSPP) solution to remove the core materials. We found that BSPP, in addition to being an effective silver oxidant, was also a good solubilizer for AgCl nanoparticles at room temperature. This allowed us to prepare phase-pure Pt nanoboxes from the as-synthesized Ag*−Pt nanocubes using a greatly simplified posttreatment for AgCl, a reaction byproduct and known impurity in the synthesis of hollow nanostructures by the replacement reaction approach (Ag* is used here to denote nanocomposites of Ag and AgCl). We also showed that AgCl functioned as a removal template in enabling a shape-controlled synthesis of the nanostructures.