Dendritic forest-like Ag nanostructures were deposited on a silicon wafer through fluoride-assisted galvanic replacement reaction (FAGRR) in aqueous AgNO3 and buffered oxide etchant. The prepared nanostructures were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma–optical emission spectroscopy, a surface profiler (alpha step), and X-ray diffraction. Additionally, the dendritic forest-like Ag nanostructures were characterized using surface-enhanced Raman scattering (SERS) when a 4-mercaptobenzoic acid (4-MBA) monolayer was adsorbed on the Ag surface. The Ag nanostructures exhibited intense SERS signal from 4-MBA because of their rough surface, and this intense signal led to an intense local electromagnetic field upon electromagnetic excitation. The enhancement factor for 4-MBA molecules adsorbed on the Ag nanostructures was calculated to be 9.18 × 108. Furthermore, common Raman reporters such as rhodamine 6G, 4-aminothiolphenol, 5,5′-dithiobis-2-nitrobenzoic acid, and carboxyfluorescein (FAM) were characterized on these dendritic forest-like Ag nanostructures, leading to the development of an ultrasensitive SERS-based DNA sensor with a limit of detection of 33.5 nM of 15-mer oligonucleotide.
In this study, Chalcopyrite (CuFeS2) was prepared by a hydrothermal and co-precipitation method, being represented as H-CuFeS2 and C-CuFeS2, respectively. The prepared CuFeS2 samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy mapping (EDS-mapping), powder X-ray diffractometer (XRD), X-ray photoelectron spectrometry (XPS), and Raman microscope. Rhodamine B (RhB, 20 ppm) was used as the target pollutant to evaluate the degradation performance by the prepared CuFeS2 samples. The H-CuFeS2 samples (20 mg) in the presence of Na2S2O8 (4 mM) exhibited excellent degradation efficiency (98.8% within 10 min). Through free radical trapping experiment, the major active species were •SO4− radicals and •OH radicals involved the RhB degradation. Furthermore, •SO4− radicals produced from the prepared samples were evaluated by iodometric titration. In addition, one possible degradation mechanism was proposed. Finally, the prepared H-CuFeS2 samples were used to degrade different dyestuff (rhodamine 6G, methylene blue, and methyl orange) and organic pollutant (bisphenol A) in the different environmental water samples (pond water and seawater) with 10.1% mineral efficiency improvement comparing to traditional Fenton reaction.
A series of hands-on experiments
including the synthesis and application
of flexible, conductive silver-nanopaste were designed to gain knowledge
of conductive soft nanomaterial and the synthesis and the application
of silver nanopaste (Ag nanopaste). The aim of this laboratory experiment
is to provide undergraduate/graduate students an introduction to flexible,
conductive electronics by the preparation of silver-nanopaste-incorporated
tracks. For Ag-nanopaste-based electronics, the packability of silver
nanoparticles and the sintering process are two major factors that
dominate the conductivity of the device. In this experiment, ethylene
glycol and polyvinylpyrrolidone were utilized to synthesize Ag nanopaste
from AgNO3 via chemical reduction. The application of this
flexible, conductive nanomaterial was demonstrated using Ag-nanopaste-incorporated
tracks with a photonic sintering process. The process of photonic
sintering is used in this experiment to reduce processing time. Prior
to performing hands-on laboratory experiments, students learned about
the properties, synthesis, and applications of flexible, conductive
nanomaterials in class. A questionnaire was administered after the
hands-on experiments to acquire student feedback on the course design.
A simple quiz was also completed by the students before and after
the hands-on experiments for evaluation.
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