Abstract
Controlling chemical reactions by plasma is expected to be a new method for improving the structural properties of substrates. An Au nanojar array was prepared when Au was deposited onto a 2D polystyrene (PS) array. The site-selective chemical growth of Ag nanoparticle rings was realized around the Au nanojar necks by a local surface plasmon resonance (LSPR)-assisted chemical reaction. The catalytic hotspots in the nanostructure array could be controlled by both etching the nanojars and Au or TiO2 sputtering onto the nanojars, which were confirmed by the growth sites of the Ag nanoparticle in the LSPR-assisted chemical reaction. The structure of the nanojars and the electric field distributions of the growing nanoparticles were simulated and analyzed using Finite-Difference Time-Domain. FDTD simulations showed that the changes in the nanojar shape led to the changed hotspot distributions. At the same time, tracking the hotspot shifts in the process of structural change was also achieved by the observation of Ag growth. Nanoarray structure prepared by LSPR-assisted chemical reaction is one of the hot fields in current research and is also of great significance for the application of Surface-Enhanced Raman Scattering.
Highlights
When a noble metal nanostructure is excited by an external electromagnetic field, optical resonances will occur due to the collective oscillations of conduction electrons along the surface of the noble metal nanostructures
Changing the flux of microfluidic motion by regulating the size of the nanogaps is helpful for studying the transfer of catalytic hotspots and tracking hotspots in the process of structural changes
Combining local surface plasmon resonance (LSPR) with a chemical reaction is a relatively new research field, in which the electric field intensity of the plasmonic structure is adjusted to implement the regulation of the chemical reaction product at a specific location, which makes plasma-assisted chemical reactions one of the main topics in plasma-related studies
Summary
When a noble metal nanostructure is excited by an external electromagnetic field, optical resonances will occur due to the collective oscillations of conduction electrons along the surface of the noble metal nanostructures. When LSPR occurs, the electric field on the surface of the local nanostructure is greatly enhanced, providing sufficient catalytic hotspots for the nucleation of nanoparticles and creating infinite possibilities for the application of plasma structures in various chemical reactions. The unique physical effects of surface plasmas help to break through the free potential barrier and are used to control the chemical growth of reactions at specific locations. The hotspots distribution is proven to change through plasma-assisted chemical growth of Ag nanoparticles and FDTD simulation. This method has great potential in surface enhancement spectroscopy, photonic crystal construction, structural defect repair, and other related fields
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