Self-assembly Preparation And Optical Properties Of Noble Metal Nanoparticle Arrays

The micro/nano structure array composed of noble metal(Au,Ag,etc.)nanoparticles(NPs)can produce localized surface plasmon resonance(LSPR),surface lattice resonance(SLR)and other phenomena under the excitation of the light field.It is widely used in optical sensing,surface enhanced Raman scattering(SERS),structural color,photocatalysis,and other fields.However,the traditional etching preparation method of precious metal arrays requires relatively expensive etching equipment,which seriously hinders the in-depth investigation of the optical performance and device applications of precious metal micro/nano arrays.In contrast,the self-assembly method based on metal NPs,due to its advantages of low cost,simple operation,flexiblility,and controllability,can overcome the shortcomings of traditional etching methods,and is expected to promote the optical property research and devices applications of micro/nano structure arrays.This dissertation aims to develop low-cost self-assembly methods for metal micro/nano structure arrays fabrication,to study its plasmon coupling characteristics and optical sensing applications,and the main results are as follows:(1)A low-cost preparation method of binary "core-satellite" NP arrays is developed:The Au NP arrays prepared by colloidal lithography are used as templates,and the Au NPs in solution are self-assembled around the template Au NPs during the evaporation process.It has the ability to control the key parameters of the array(such as the size,composition,morphology of the NPs constituting the array,and the array periodicity).A new design strategy for anti-counterfeiting label materials is proposed,which use gorgeous structure color and dynamic SERS performance of the binary array as anti-counterfeiting identification methods.(2)A simple preparation method of flower-shaped Au@Ag NP arrays is developed:Interlaced Ag nanosheets are in-situ chemical reduced on the template Au NP array prepared by colloidal lithography.The flower-shaped array with uniform morphology can be fabricated reproducibly on the centimeter scale at low cost.The array achieves ultra-sensitive SERS detection of the pesticide molecule thiram,with a detection limit of 10-11 M and a SERS enhancement factor of 1.01 × 107,while ensuring the signal uniformity on a large area(100 × 60 μm2).(3)Close-packed Au NP arrays are successfully prepared by electrostatic self-assembly combined with substrate volume shrinkage.Large-area monolayer close-packed Au NP arrays can be simultaneously constructed on the upper and lower surfaces of hydrogel film.The formation mechanism of the close-packed Au NP array is investigated.A highly sensitive and reproducible SERS detection of the dye molecule amaranth is realized,the detection limit can reach 10-8 M,and the relative standard deviation of signal intensity is 8.1%.(4)An inkjet printing preparation method for multi-functional SERS microchip based on the ordered array of three-dimensional Au NP dome-shaped structure is developed.SERS analysis of multiple samples(including dye molecules,food additive molecules,and pesticide molecules)on one SERS microchip without interference betweent samples is realized.The bowl-shaped structure composed of Au NPs is successfully fabricated using inkjet printing.The self-assembly formation mechanism of the dome-shaped structure and bowl-shaped structure composed of Au NPs is investigated.Therefore,the simple and economical preparation methods of several precious metal micro/nano structure arrays proposed in this thesis are of great significance for the development of precious metal arrays from laboratory theoretical research to practical applications.