Dual Functions Of Asymmetrical Plasmonic Structures

In recent years,with the continuous development of science,people have mastered a variety of new nano-manufacturing technologies and control processes,and can use these technologies to produce metal nanostructures with a variety of shapes and functions.These metal nanostructures can cause surface plasmon resonance and exhibit a variety of optical properties.Because of the resonance of the surface plasmon,the local electromagnetic field in the metal micro-nano structure can be excited,and the conversion efficiency of various optical processes sensitive to the field intensity is effectively improved.The well-designed plasmonic structures have excelled in Surface-Enhanced Raman Scattering(SERS),photothermal therapy,and solar energy conversion sterilization,and have attracted much attention.SERS is a fingerprint detection technology for probe molecules.Because it is highly sensitive,non-destructive,SERS is now widely used in materials,chemistry,and medicine.In addition,photothermal conversion based on metal nanoparticles has been rapidly.People design various types of substrates,particle shapes,and devices so that the light absorption rate and light-to-heat conversion efficiency of the substrate can be greatly improved.Applying it to solar-driven steam conversion has made much progress.In this paper,Asymmetrical Plasmonic Structures(APS)with dual functions is developed.The research mainly includes the following aspects:1.We have tested the absorption performance of the front side of APS and its Raman enhancement effect as a SERS substrate for R6G molecules.The structure of the APS Raman enhancement mechanism was further explained by the SEM characterization of the structure and the results of the simulation calculations.Because of its high density of plasmon hot spots and obvious local electromagnetic field enhancements,the shiny side of APS can be used to detect sensitive chemicals with a detection limit as low as 10-12 M and an enhancement factor as high as 109.The sample shows good performance in uniformity,whether macroscopically or microscopically,the relative standard deviation(RSD)of Raman signals in different regions is about 5%.In addition,we used a variety of probe molecules for Raman detection and found that APS showed universality for a variety of dye molecules.2.We also studied the photothermal conversion performance of APS.We used the reverse side of the APS as absorber.It was found that the APS reverse surface has an absorbance of over 80%in an range of 400 to 2500 nm.Then we used it for solar energy-driven steam generation experiments to test its light-to-heat conversion efficiency.Because of its low density and porosity,it can naturally float on the surface of the water.Through the interface heating,it can effectively convert the surface water molecules into steam.APS's black porous surface has a photothermal conversion efficiency of more than 80%under four standard solar irradiation intensities,enabling efficient solar-driven steam generation.3.In this study,we for the first time demonstrated that APS formed by dense self-assembled silver nanoparticles can achieve dual functions—solar water purification and contaminant detection.We designed the device and conduct an outdoor experiment with a portable Raman detector.It was found that APS can combine the two functions of pollutant detection and sewage purification.We performed a cycling experiment to verify the stability of the sample.We found that both the detection and purification features demonstrated long-term durability of up to 45 days,with a reduction in Raman intensity of less than 20%,and a reduction in photothermal conversion efficiency of less than 10%.