Anisotropic Nanoparticle Arrays Guided by Ordered Nanowire Films Enhance Surface‐Enhanced Raman Scattering

Abstract

platforms with high sensitivity to identify the presence of toxic substances. [8][9][10] Currently, plasmonic metals gold (Au), silver (Ag), and copper (Cu), have extensively been exploited as SERS platforms mainly due to their significantly enhanced Raman signal at the nanoscale evolved from their plasmonic features. [11][12][13] These metal nanoparticles could be easily assembled to improve their performance, [14][15][16][17] and effectively control the detected signal intensity by regulating the intrinsic activity. [18][19][20] When plasmonic nanoparticles (NPs) are closely aligned, a considerable number of hotspots are created in the vicinity area and enhance the Raman signals. [21][22][23][24][25][26] To obtain unique nanostructures with high SERS sensitivity, various methods have been used to assemble plasmonic nanoparticles into controllable order and superstructures for desired properties, such as self-evaporation, [27,28] DNA-assisted, [29,30] field-induced, [31,32] laser micro/nano-fabrication, [33][34][35][36] and photolithography patterning templates. [37][38][39][40] However, the fabrication of highly ordered and homogeneous nanostructures by these methods implies control over a multitude of parameters, including the surface chemistry interactions of building blocks, solvent evaporation rate, vectorization of the applied field, and sophisticated patterned template design. Precise control of these parameters reduces the efficiency of preparing well-ordered, tightly packed SERS substrates, and increases the difficulty of nanostructure regulation and the corresponding fabrication costs. Importantly, the existing works rarely explore the ordering effect of materials on the SERS performance.Here, we report a new way for higher SERS activity by assembling the disordered materials into the ordered structures. The ordered tellurium (Te) nanowire (NW) templates are used to lead the alignment of Au nanoparticles, similar to textile threads in clothing, and the resulting Au NPs are connected in series along ordered arrangement nanowires to form ordered close-packed nanostructures. Unlike complicated and tedious ordered assembly methods, the ordered nanowire templates used to guide the assembly of Au NPs can be quickly obtained by the liquid-air interfacial assembly method, which is suitable for a variety of substrates, including rigid silicon Designing high-efficiency surface-enhanced Raman scattering (SERS) substrates has attracted explosive attention in recent decades for their novel and potential applications. Great achievements have been made to optimize the intrinsic activity of nanomaterial in SERS substrates, while little attention has been paid to the unique structural design of the nanomaterial building blocks. Herein, a new strategy is provided for assembling Au nanoparticles into well-defined ordered structures by using a highly ordered arrangement nanowires template to explore the ordering effect on the SERS performance. The highly ordered Au nanoparticle arrays show a detection limit of 10 −9 m tha...

Exploring Deposition Techniques and Supramolecular Arrangement in Thin Films for Sensor Applications

“…The enhancement factor was 10 5 and 10 9 for 2,4-dinitrotoluene and Rhodamine 6G, respectively. Recently, Sheng et al [104] have fabricated ordered LB TeNWs film to further immerse in HAuCl 4 aqueous solution. After the reduction, the ordered Te-Au hetero NWs film was tested as a SERS substrate.…”

“…Additionally, the Te-Au hetero NWs film exhibits excellent uniformity and flexibility. Interestingly, a test using a polarized laser indicated that the local field that dominates the SERS signal is perpendicular to the NW template in the axial direction, while the intensity is independent of the angle of polarized light for the disordered film [104].…”