Chemically
reduced graphene oxide possesses unique properties and
leads to a secure processing method for many applications. The electrical
and optical properties of graphene oxide are strongly dependent on
the chemical and atomic structure. In the present work, the reduction
of synthesized multilayer graphene oxide sheets by both chemical and
thermal methods to use them as a substrate in the field of molecular
electronic device fabrication is reported. 1-Dodecanethiol molecules
are used to covalently bond on the surface atoms of reduced graphene
oxide to constitute molecular electronic devices. The metal–organic
molecules–reduced graphene oxide–metal junctions show
a significant reduction in current levels and weak diode behavior.
The observations confirm the tunneling as the conduction mechanism.
The sheets are low cost, highly flexible, and can be used as a substrate
to build the molecular electronic junctions.
In the present work, gold (Au), silver (Ag), and copper
(Cu) based
mono- and bimetallic NPs are prepared using a cost-effective facile
wet chemical route. The pH for the synthesis is optimized in accordance
with the optical spectra and supported by the finite difference time
domain simulation studies. FESEM and TEM micrographs are used to analyze
the morphology of the prepared nanoparticles. TEM images of bimetallic
nanoparticles (BMPs) verified their bimetallic nature. XRD studies
confirmed the formation of fcc-structured mono- and bimetallic NPs.
Photoluminescence studies of the as-synthesized NPs are in good agreement
with the previous publications. These synthesized NPs showed enhanced
catalytic activity for the reduction/degradation of 4-nitrophenol,
rhodamine B, and indigo carmine dyes in the presence of sodium borohydride
(NaBH
4
) compared to NaBH
4
alone. For the reduction
of 4-nitrophenol, Au, Cu, and CuAg nanoparticles exhibited good catalytic
efficiency compared to others, whereas for the degradation of rhodamine
B and indigo carmine dyes the catalytic efficiency is comparatively
high for CuAg BMPs. Furthermore, the antibacterial assay is carried
out, and Ag NPs display effective antibacterial activity against
Klebsiella pneumoniae
,
Salmonella
ser.
Typhimurium,
Acinetobacter baumannii
,
Shigella
flexneri
, and
Pseudomonas aeruginosa
.
Bimetallic nanoparticles (BNPs) have drawn significant attention due to their numerous applications. They demonstrate enhanced optical, electrical, thermal, and catalytic properties due to the synergistic effects of monometals present in them. In this work, CuAg and AuAg BNPs have been synthesized using a facile and economical chemical reduction method. Optical characterization was carried out using UV–visible spectroscopy, and effect of pH on optical absorbance was studied. For CuAg and AuAg BNPs, optimum pH was observed to be at 9.4 and 6.39, respectively. Morphological investigation confirms the average diameters of CuAg and AuAg BNPs were to be 65 nm and 30 nm, respectively. Photocatalytic property illustrates the reduction of 4-nitrophenol to 4-aminophenol with a 92% conversion percentage in the presence of CuAg BNPs in 4 min, and rate constant for the reaction was measured to be 8.98 × 10–3 s−1. But for the AuAg BNPs, the conversion percentage was 97% in 8 min and rate constant was found to be 7.95 × 10–3 s−1. Thermal conductivity and viscosity measurements of the nanofluids obtained with CuAg and AuAg BNPs have ascertained them to be efficient candidates for the heat transfer and catalytic applications.
Graphic abstract
Soldering is a physical process in which one metal melts and joins the other to form a strong bond, which further helps in electron conduction and increases the mechanical strength in any electronic circuits. The present work demonstrates the development of graphene-based flux comprising of 2 g of graphene and 2 ml of phosphoric acid for the residue-free, high stability, durable, and two-step soldering of copper wire on to the surface of the copper-based printed circuit board. The soldering flux can be applied to the copper, and wire can be soldered in ambient conditions using commercial soldering iron at a standard soldering temperature of 260℃. This flux helps the formation of strong and electrically conducting joints between the copper wire and copper-based printed circuit board. The joints are studied with scanning electron microscope images, and energy dispersive X-ray mapping successfully shows the formation of a joint between the copper wire and the copper and also shows the presence of graphene between the joint.
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