The Construction And Functional Application Of Plasmonic Nanoparticle Monolayer Film

The construction and functional application of plasmonic nanoparticle monolayer film has great exploration value and significance for the further research and application of precious metal nanomaterials in various fields such as catalysis,sensing,surface-enhanced Raman scattering(SERS)and oil-water separation.The material's functions mainly depend by their shapes and the properties of moleculars,and they also produce assembled synergy effects,hybrid superposition effects,and composite common effects.The current bottom-up self-assembly method is the simplest and most effective method for constructing functional plasmonic nanoparticle monolayer films,such as the commonly used gas-liquid and liquid-liquid interface nanoparticle self-assembly.Adjusting different self-assembly modes and hybrid systems can expand the functional applications of plasmonic nanoparticle monolayer films.This thesis focuses on the following three sections:1.Macroscopic Au@PANI Core/Shell Nanoparticles Superlattice Monolayer Film with Dual-Responsive Plasmonic SwitchesIn this system,gold nanoparticles were coated by polyaniline(PANI)and then self-assembled into a monolayer film at the air-liquid interface.The PANI shell plays two important roles in the superlattice monolayer film.First,the PANI shell acts as a physical spacer to provide a steric hindrance to counteract the van der Waals(vd W)attraction between densely packed nanoparticles(NPs),resulting in the formation of a superlattice by adjusting the thickness of the PANI shell.Second,the PANI shell provides the superlattice film with multiple stimuli such as electrical potential and p H change,leading to reversible optical and plasmonic responsiveness.The superlattice monolayer film can show a vivid color change from olive green to pink,or from olive green to violet by the change of the corresponding stimuli.Also,the localized surface plasmonic resonance(LSPR)of the superlattice monolayer film can be reversibly modulated both by changing the p H and applying an electric potential.Notably,a significant plasmonic shift of 157 nm can be achieved in the superlattice monolayer film when the PANI shell with a thickness of 35 nm and gold nanorod as a core were used.The superlattice monolayer film with dual-responsive plasmonic switches is promising for a range of potential applications in optoelectronic devices,plasmonic and colorimetric sensors,and surface-enhanced Raman scattering(SERS).2.Two-dimensional Free-standing Platinum Supra-Nanostructures Monolayer Film with Excellent Electrocatalytic Activity for Fuel Cell ApplicationIn this system,a universal strategy to construct a two-dimensional(2D)large-area hollow platinum(Pt)supra-nanostructures film through the sacrificial template method was developed.The Pt supra-nanostructure film exhibits high catalytic activity and excellent durability for the electrooxidation of methanol and ethanol,owing to its unique ultra-thin hollow structure and synergistic effects of closely arranged arrays,which would effectively improve the atom utilization rate and the electron transfer rate.The Pt supra-nanostructures film with the thickness of 6 nm was the most prominent for the methanol catalytic reaction,showed a mass-normalized activity of 116.67m A mg^-1,which was higher than most reports.The film also had outstanding cycle stability with more than 200 CV cycles.The Pt supra-nanostructures monolayer film is a promising candidate as high-performance electrocatalyst for fuel cells.3.Design and Simulation Sandwich-type SERS Sensor Based on Vertically Free-Standing Gold Nanobipyramids Monolayer FilmIn this system,a vertically free-standing gold nanobipyramids(Au NBRs)sandwich-type SERS sensor was designed based on the oil-water interface self-assembly method.First,the gold nanobipyramid has a narrower plasmonic peak width and a stronger local electric field enhancement effect than nanoparticle and nanorod through FDTD simulation.According to the principle of minimum surface energy,Au NBRs can stand vertically at the oil-water interface to form a 2D monolayer array,and then a sandwich-type structure was constructed by superimposing two-layer arrays.The structure can not only make full use of the contact of the tips to produce a tip effect,but also greatly increase the SERS hotspot area to capture more probe molecules falling into the hotspot,and then further enhance the SERS signal through the hotspot effect.Meanwhile,the sandwich-type structure also ensures the stability and repeatability of the SERS results.