2D Stranski–Krastanov growth of planar AuAg nano-dendrimers for enhanced visible-light plasmonic catalysis

Abstract

Plasmonic bimetallic nanostructures with complex morphologies offer enhanced light-harvesting and catalytic properties. Herein, we report the one-pot synthesis of two-dimensional, dendrimer-shaped gold–silver (AuAg) bimetallic nanoparticles via ascorbic acid reduction with the presence of docosyltrimethylammonium chloride and hexamethylenetetramine in an ice-water bath. The synthesized nanoparticles feature a unique planar, branched morphology with arm lengths of approximately 50 nm and trunk diameters of ∼10 nm, as confirmed by electron microscopy. Owing to the localized surface plasmon resonance (LSPR) covering the visible region, we demonstrate their efficacy as plasmonic catalysts under low-power visible light irradiation (590 nm LED). In particular, enhanced catalytic activity was observed in a model reaction compared to dark conditions, which is attributed to the efficient generation and injection of hot electrons from the visible-light-excited plasmonic nanostructures. Finite element method (FEM) electromagnetic simulations corroborate that this specific morphology generates intense localized field enhancements at the branch tips and supports a strong plasmonic response tuned to the visible region. This work highlights the potential of morphologically engineered bimetallic nano-dendrimers as high-performance photocatalysts for sustainable chemistry driven by visible light.