Light-Controlled Shrinkage of Large-Area Gold Nanoparticle Monolayer Film for Tunable SERS Activity

Abstract

The two-dimensional (2D) monolayer gold nanoparticle (Au NP) film is of significant interest and importance in both fundamental and practical applications including optoelectronic devices, sensing, catalysis, and surface-enhanced Raman spectroscopy (SERS). Because of the weak physical interaction, the conventional monolayer Au NP film fabricated at the oil–water interface was unstable, easily breakable, and difficultly transferred. In the present work, we report on a simple and effective chemical cross-linking strategy at the air–water interface to achieve a large-scale monolayer gold nanoparticle film with intelligently tunable size of nanogaps, and excellent free-standing and easily transferable properties. In our strategy, acrylamide, a polymerizable molecule, was first modified on the surface of Au NPs for subsequent self-assembly into a monolayer film at the liquid–liquid interface. Through photopolymerization of acrylamide, a chemically cross-linked film was formed with closely packed nanoparticles,...