Browsing by Subject "Ag nanostructures"
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Item Open Access Fabrication of flexible, cost-effective, and scalable silver substrates for efficient surface enhanced Raman spectroscopy based trace detection(Elsevier BV, 2021-06-20) Khan, G. A.; Demirtaş, Ö.; Aytekin, Ö.; Demir, Ahmet Kemal; Bek, A.; Bhatti, A. S.; Ahmed, W.The fabrication and optimization of cost-effective, eco-friendly, uniform and flexible SERS platforms by facile synthesis routes has recently attracted great attention for trace detection of various analytes. Herein, we report the fabrication of interconnected Ag nanostructures on the unmodified filter paper-based flexible substrates by a facile recipe, which involves evaporation of Ag precursor solution on the filter paper followed by its reduction with a strong reducing agent, NaBH4. The fabrication process is time-efficient, reproducible, and has the potential of being scaled up. The presence of inter-connected nanostructures results in high concentration of uniformly distributed hotspots on the substrate, which in turn provide excellent and reproducible SERS sensitivity. The finite element simulation results showed that fabricated nanostructures are much more effective for field enhancement as compared to the agglomerated spherical nanoparticles. Crystal violet (CV) concentration of 10−8 M was easily detected with these substrates both via solution drying and swabbing. Similarly, AgFPS have proven effective for swab-based detection of urea nitrate (UN), a well-known constituent of homemade explosives. The C-N and NO3- symmetric stretching modes of UN are detectable down to 1 µM and 100 µM concentrations, respectively. Moreover, these substrates showed SERS signal uniformity both from different spots of a single substrate, and substrates from different batches, with spot-to-spot relative standard deviation (RSD) of 15% and sample-to-sample RSD of 15–19%. This makes them excellent for reliable and quick quantitative detection. The simple synthesis strategy, flexibility, cost-effectiveness, and quantitative detection makes these substrates ideal for SERS based trace detection, especially for on-site analysis, and various sensing applications.Item Open Access Solid substrates decorated with Ag nanostructures for the catalytic degradation of methyl orange(Elsevier, 2018) Şakır, M.; Önses, M. SerdarThere is a strong demand for development of catalytically active solid substrates for heterogeneous catalysis applications. This study reports fully solution-processable and scalable fabrication of solid substrates decorated with Ag nanostructures for the degradation of organic dyes. Ag nanostructures were prepared by direct surface-growth from Pt nanoparticles that were immobilized on Si substrates modified with a layer of end-grafted poly(2-vinylpyridine). The proper choice of the growth conditions and seed-selective growth from Pt nanoparticles were critically important in fabricating Ag nanostructures with high catalytic activity and large surface coverage. The catalytic performance of the presented platform was studied by the reduction of methyl orange by borohydride ions and monitored using UV–visible spectrometry. The substrates exhibited high catalytic activity enabling degradation of 10−5 M methyl orange solution in less than an hour with an apparent reaction rate constant of 33.5 × 10−3 min−1. The substrates can be easily removed from the degradation medium and used multiple times. Our approach presents an effective strategy for waste water management applications avoiding the agglomeration and separation issues of colloidal catalysts and overcoming the need for tedious and costly fabrication of thin films.