Au-on-Ag nanostructure for in-situ SERS monitoring of catalytic reactions

2022 ◽  
Author(s):  
Shuyue He ◽  
Di Wu ◽  
Siwei Chen ◽  
Kai Liu ◽  
Eui-Hyeok Yang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Thermal Evaporation ◽  
Reduction Process ◽  
Ag Nps ◽  
Au Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Raman Probe

Abstract Dual-functionality Au-on-Ag nanostructures (AOA) were fabricated on a silicon substrate by first immobilizing citrate-reduced Ag nanoparticles (Ag NPs, ~43 nm in diameter), followed by depositing ~7 nm Au nanofilms (Au NFs) via thermal evaporation. Au NFs were introduced for their catalytic activity in concave-convex nano-configuration. Ag NPs underneath were used for their significant enhancement factor (EF) in surface-enhanced Raman scattering (SERS)-based measurements of analytes of interest. Rhodamine 6G (R6G) was utilized as the Raman-probe to evaluate the SERS sensitivity of AOA. The SERS EF of AOA is ~37 times than that of Au NPs. Using reduction of 4-nitrothiophenol (4-NTP) by sodium borohydride (NaBH4) as a model reaction, we demonstrated the robust catalytic activity of AOA as well as its capacity to continuously monitor via SERS the disappearance of reactant 4-NTP, emergence and disappearance of intermediate 4, 4’-DMAB, and the appearance of product 4-ATP throughout the reduction process in real-time and in situ.

scholarly journals Stabilizing Ag Nanoparticles Using Anatase TiO2 and Cu on Al Surface

2020 ◽  
pp. 22-30
Author(s):  
Masayoshi Kaneko
Keyword(s):  
Ag Nanoparticles ◽  
Au Nanoparticles ◽  
Active Surface ◽  
Anatase Tio2 ◽  
Sers Substrate ◽  
Ag Nps ◽  
Au Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Chemical adsorption of anatase TiO2, silver nanoparticles (Ag NPs), and Cu particles (Cu Ps) on aluminum (Al) surface yielded an active surface-enhanced Raman scattering (SERS) substrate. TiO2 is known to reduce both silver (Ag) and copper (Cu). In an oxidizing environment, Ag NPs remain unoxidized since Cu has a more negative redox potential than Ag. Ag is therefore protected by Cu from getting oxidized. Although Ag NPs exhibit better SERS activity than Au NPs, Ag is relatively easier to oxidize, limiting the development of Ag-based nanomaterials. Therefore, despite the poor SERS activity of Au nanoparticles than that of Ag nanoparticles, Au nanoparticles have been widely used. Herein, the stabilization of Ag nanoparticles by incorporating a reductive process using anatase TiO2 is reported. The fabricated substrates bearing anatase, Ag NPs, and Cu Ps were stable, as seen by Raman spectra, and remained unchanged for more than 2 months.

SILVER NANOPARTICLES FILMS DEPOSITED ON AAO TEMPLATES BY THERMAL EVAPORATION FOR SURFACE-ENHANCED RAMAN SCATTERING OF R6G

NANO ◽  
2012 ◽  
Vol 07 (06) ◽  
pp. 1250048 ◽  
Author(s):  
JIANPING LIN ◽  
HUIQING LAN ◽  
WEIFENG ZHENG ◽  
YAN QU ◽  
FACHUN LAI
Keyword(s):  
Silver Nanoparticles ◽  
Raman Scattering ◽  
Thermal Evaporation ◽  
Particle Diameter ◽  
Surface Enhanced Raman Scattering ◽  
Average Particle ◽  
Ag Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Silver nanoparticles (NPs) films with different nominal thicknesses were deposited on the anodic aluminum oxide (AAO) templates with pore diameter about 200 nm by thermal evaporation. These NPs films were used as the surface enhanced Raman scattering (SERS) active substrates. The microstructure and surface morphology of the films were studied by X-ray diffraction and scanning electron microscopy, respectively. The SERS activity of the films was investigated by Raman scattering of adsorbed rhodamine 6G (R6G) at different concentrations. The results revealed that the average diameter of Ag NPs in different samples is 58 nm, 75 nm, 93 nm and 108 nm, respectively. Ag NPs film on AAO template is very suitable as a SERS active substrate and can detect R6G molecules with a concentration of 10-8 M. The intensity of the SERS spectra is related to both the Ag NPs size and interparticle distance. The sample with an average particle diameter of 93 nm has the highest SERS enhancement factor (1.3 × 106).

Nitrogen-doped graphene network supported copper nanoparticles encapsulated with graphene shells for surface-enhanced Raman scattering

Nanoscale ◽  
2015 ◽  
Vol 7 (40) ◽  
pp. 17079-17087 ◽  
Author(s):  
Xiang Zhang ◽  
Chunsheng Shi ◽  
Enzuo Liu ◽  
Jiajun Li ◽  
Naiqin Zhao ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Chemical Vapor ◽  
Surface Enhanced Raman Scattering ◽  
Nitrogen Doped ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
Enhanced Raman Scattering

Nitrogen-doped graphene network supported graphene shell encapsulated Cu nanoparticles for surface-enhanced Raman scattering were constructed by in situ chemical vapor deposition.

scholarly journals Large-Scale Fabrication of Ultrasensitive and Uniform Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Pesticides

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 520 ◽  
Author(s):  
Jia Zhu ◽  
Guanzhou Lin ◽  
Meizhang Wu ◽  
Zhuojie Chen ◽  
Peimin Lu ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Large Scale ◽  
Capillary Flow ◽  
Surface Enhanced Raman Scattering ◽  
Ag Nps ◽  
Uniform Size ◽  
Sers Substrates ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Technology transfer from laboratory into practical application needs to meet the demands of economic viability and operational simplicity. This paper reports a simple and convenient strategy to fabricate large-scale and ultrasensitive surface-enhanced Raman scattering (SERS) substrates. In this strategy, no toxic chemicals or sophisticated instruments are required to fabricate the SERS substrates. On one hand, Ag nanoparticles (NPs) with relatively uniform size were synthesized using the modified Tollens method, which employs an ultra-low concentration of Ag+ and excessive amounts of glucose as a reducing agent. On the other hand, when a drop of the colloidal Ag NPs dries on a horizontal solid surface, the droplet becomes ropy, turns into a layered structure under gravity, and hardens. During evaporation, capillary flow was burdened by viscidity resistance from the ropy glucose solution. Thus, the coffee-ring effect is eliminated, leading to a uniform deposition of Ag NPs. With this method, flat Ag NPs-based SERS active films were formed in array-well plates defined by hole-shaped polydimethylsiloxane (PDMS) structures bonded on glass substrates, which were made for convenient detection. The strong SERS activity of these substrates allowed us to reach detection limits down to 10−14 M of Rhodamine 6 G and 10−10 M of thiram (pesticide).

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