Site-Selective Plasmonic and Photonic Modulation of Galvanic Replacement Reaction between Silver Nanoprisms and Aqueous Chloroplatinate Ions

Hybrid systems encompassing plasmonic silver nanoprisms (AgPRs) and efficient catalysts such as platinum (Pt) offer tremendous opportunities in advancing plasmonic chemistry toward environmentally sustainable chemical transformations. Galvanic replacement reactions (GRRs) offer a simple and versatile route to preparing such hybrid systems. Syntheses of Ag-Pt hybrids via GRRs have previously employed various platinum salts that appear to face a thermodynamic barrier while reacting with a Ag crystal. This work carefully reinvestigates the reaction between AgPRs and [PtCl₄]^2- ions and identifies the important role that crystal facets and the instability of reactant molecules can play in overcoming the uphill barrier, thus allowing the reaction to proceed to at least some extent. To overcome the poor efficiency of this reaction, the work introduces a photodriven pathway that allows control over the synthesis of Pt-coated AgPRs. Photon energy plays a role in controlling the reaction kinetics and dictating the extent to which this reaction could be enhanced, while the plasmonic modulation allows spatial biasing of the reaction kinetics at specific subsites of the AgPRs. The findings presented here enrich our mechanistic understanding of plasmon-enhanced chemical reactions, thus, expediting opportunities to deploy plasmonic chemistry for industrially important chemical transformations.