Plasmon-Assisted Synthesis of Hybrid and Reconfigurable Nanomaterials

The synthesis of plasmonic nanomaterials with tailored interfaces requires fine control over competing reductive and oxidative chemical processes. Differentially modulating the rates of these reactions using only chemical and thermal parameters can be prohibitively challenging. In such cases, excitation of the plasmon resonance of the growing nanoparticles using visible light can yield hybrid structures and morphological transformations that are not accessible via standard colloidal approaches. For example, in the synthesis of hybrid bimetallic nanoparticles composed of a plasmonically-active silver (Ag) core and a catalytically-active platinum (Pt) shell, excitation of the plasmon resonance of the core nanostructure selectively drives the reduction of a Pt precursor under chemical conditions that limit the competing galvanic exchange between Pt ions and Ag. The combination of plasmon-driven reduction rate control with chemical reduction rate control also enables the synthesis of Ag core-Pt satellite nanostructures that are not accessible via other approaches. In another example, plasmonic excitation of Ag triangular prisms drives a cycle of oxidation and re-reduction of Ag to yield a conversion of the planar twinned prisms to multiply twinned icosahedra. The use of light to reconfigure the defect structure of Ag nanoparticles opens opportunities for visible-light-tunable catalysis and recyclable catalyst materials.