Kinetic Trapping of Immiscible Metal Atoms into Bimetallic Nanoparticles through Plasmonic Visible Light-Mediated Reduction of a Bimetallic Oxide Precursor: Case Study of Ag-Pt Nanoparticle Synthesis

Alloying of two metals is commonly used to create nanomaterials with unique physical and chemical properties. The ability to synthesize well-mixed bimetallic alloy nanoparticles, however, is often limited by the intrinsic immiscibility of metals. To overcome this issue, extreme synthesis conditions, using high energy gamma radiation or very high temperatures, have been employed to trap metal atoms of immiscible metals in well-mixed alloy nanostructures. Herein, we demonstrate a more benign synthesis strategy for creating well-mixed bimetallic nanoparticles of immiscible metals. We demonstrate a formation of Ag-Pt bimetallic nanoparticles through the visible-light mediated reduction of a hollow bimetallic oxide precursor containing Ag and Pt oxide. We exploit the optical properties of Ag by using visible light to excite surface plasmon resonance to drive the reduction of the Pt oxide thereby destabilizing the bimetallic precursor. Under the influence of resonant light the hollow bimetallic precursor restructures forming well-mixed Ag-Pt alloy nanoparticles.