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Synthesis of Si-based KH560/RGO@Fe3O4 composite for improving electromagnetic properties in 2–18?GHz frequency range
摘要： Silicon coupling reagent is regarded as a common additive on surface treatment of polymer due to its high bonding strength and low cost. In this paper, a series of γ-(2, 3-epoxypropoxy) propyltrimethoxysilane (KH560)-based reduced graphene oxide (RGO)@Fe3O4 (KH560/RGO@Fe3O4) composites with different ratio of Fe3O4 nanoparticles (NPs) are synthesized by a facile hydrothermal method. It is confirmed that the silicon reagent KH560, as a hopeful candidate for increasing the RGO lattice defects, is favorable to improve the electromagnetic wave absorption. Meanwhile, the microwave attenuation mechanism of KH560/RGO@Fe3O4 composite suggests that the dielectric loss mainly causes by multiple Debye dipolar relaxation and its magnetic loss comes from the eddy-current effect of Fe3O4 NPs over the high frequency range. In consequence, the KH560/RGO@Fe3O4 composite endows the excellent absorption performance, the reflection loss (RL) value is optimized to ? 25 dB at 14.1 GHz with a thickness of 3 mm and the maximum frequency bandwidth for RL < ? 10 dB is 4.1 GHz with a thickness of 4 mm.
关键词： Electromagnetic wave absorption,Fe3O4 nanoparticles,Reduced graphene oxide,Hydrothermal method,Silicon coupling reagent
更新于2025-09-04 15:30:14
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Silicon-grafted Ag/AgX/rGO nanomaterials (X = Cl or Br) as dip-photocatalysts for highly efficient p-nitrophenol reduction and paracetamol production
摘要： In this work, plasmonic Ag/AgX/rGO (X = Cl or Br) nano‐photocatalysts were grafted with silicon by adding trimethylsilyl chloride as silicon precursor. The synthesized Ag/AgX/rGO‐Si hybrids showed a large improvement of photocatalytic activity towards the synthesis of p‐aminophenol (PAP) as well as paracetamol (acetaminophen; APAP) through the photoreduction of p‐nitrophenol (PNP). The prepared catalysts Ag/AgX/rGO were characterized using SEM, XRD, FTIR and the reduction reaction of p‐nitrophenol was monitored by UV–Vis measurements, GC/MS and 1HNMR data. From the results, it was demonstrated that the rate order of reduction process of the PNP to PAP and to APAP under visible light irradiation of the samples was as follows; Ag/AgBr/rGO‐Si > Ag/AgCl/rGO‐Si > Ag/AgBr/rGO > Ag/AgCl/rGO. The reaction mechanism had been postulated that was supported with the spectroscopic data. In addition, the catalysts were recovered from the reaction medium and re‐used in three cycles that indicated the reusability and stability of the catalysts. This study was featured by the following; i) fast reaction, ii) the reduction of p‐nitrophenol to paracetamol was performed in a facile one‐pot reaction compared to previous approaches that tends to reduce the production cost, and iii) investigations on the catalytic properties of Ag/AgX/rGO in organic transformations open the door to find a benefice of these catalysts in other organic reactions and in the development in the synthesis of pharmaceutical products.
关键词： reduced graphene oxide,Ag/AgX nanocomposites,P‐aminophenol,photocatalysis,paracetamol
更新于2025-09-04 15:30:14
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Reduced graphene oxide decorated with gold nanoparticle as signal amplification element on ultra-sensitive electrochemiluminescence determination of caspase-3 activity and apoptosis using peptide based biosensor
摘要： Introduction: Growing demands for ultrasensitive biosensing have led to the development of numerous signal amplification strategies. In this report, a novel electrochemiluminescence (ECL) method was developed for the detection and determination of caspase-3 activity based on reduced graphene oxide sheets decorated by gold nanoparticles as signal amplification element and horseradish peroxidase enzyme (HRP) as ECL intensity enhancing agent. Methods: The ECL intensity of the luminol was improved by using the streptavidin coated magnetic beads and HRP in the presence of hydrogen peroxide. The cleavage behavior of caspase-3 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using biotinylated peptide (DEVD containing peptide) which was coated on reduced graphene oxide decorated with gold nanoparticle. The surface modification of graphene oxide was successfully confirmed by FTIR, UV-vis and x-ray spectroscopy. Results: ECL based biosensor showed that the linear dynamic range (LDR) and the lower limit of quantification (LLOQ) were 0.5-100 and 0.5 femtomolar (fM), respectively. Finally, the performance of the engineered peptide based biosensor was validated in the A549 cell line as real samples. Conclusion: The prepared peptide based biosensor could be considered as an excellent candidate for early detection of apoptosis, cell turnover, and cancer related diseases.
关键词： DEVD-peptide,Electrochemiluminescence,Apoptosis,Reduced graphene oxide,Caspase-3,Gold nanoparticle
更新于2025-09-04 15:30:14
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Highly transparent conductive reduced graphene oxide/silver nanowires/silver grid electrodes for low-voltage electrochromic smart windows
摘要： Transparent conductive electrodes (TCEs) based on hybrid structures (silver nanowires) have been compressively reconnoitered in next-generation electronics such as flexible displays, artificial skins, smart windows, and sensors, owing to their admirable conductivity as well as flexibility, which make them favorable substitutes to replace ITO (Indium Tin Oxide) as a transparent conductor. Nevertheless, silver-based TCEs grieve from poor stability owing to the corrosion and oxidation of silver in electrolytes. To overcome these issues, a RGO (Reduced Graphene Oxide) layer on silver was promote to resolve the difficulties of corrosion and oxidation in the electrolyte. Moreover, we successfully designed and demonstrated low-voltage WO3-based electrochromic devices (ECDs) with fabricated hybrid TCEs. The hybrid electrodes with RGO/silver nanowires/metal grid/PET (RAM) electrode exhibited improvements in the switching stability and optoelectronic properties, such as the sheet resistance (0.714 ohm/sq), as well as optical transparency of 90.9%. The coloration and bleaching behavior of the ECD was observed in an applied low-voltage range of -1.0 to 0.0 V with a maximum optical difference of 72% at 700 nm, which yielded a coloration efficiency (η) of ~33.4 cm2/C. The highly conductive hybrid TCEs exhibit favorable features for numerous embryonic flexible electronics and optoelectronic devices.
关键词： Oxidation,Silver nanowires,Electrochromic devices,Reduced graphene oxide,Corrosion
更新于2025-09-04 15:30:14
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Visible active reduced graphene oxide loaded Titania for photodecomposition of ciprofloxacin and its antibacterial activity
摘要： The reduced Graphene Oxide based titanium dioxide (rGO-TiO2) nanocomposite was synthesized by a simple hydrothermal preparation and characterized by X-ray Diffraction Analysis (XRD), UV–Vis absorption spectroscopy (UV), Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The XRD pattern of rGO-TiO2 indicates the presence of anatase TiO2 and average crystalline size of particles is 32 nm. The optical band gaps of TiO2, GO and rGO-TiO2 nanocomposite are 3.24 eV, 4.3 eV and 2.7 eV respectively. Comparison of efficiencies of three catalysts shows that ciprofloxacin degrades at a faster rate under visible light irradiation in the presence of rGO-TiO2 at 60 min than in presence of pure TiO2 commercial TiO2-P25. Higher photocatalytic decomposition efficiency of rGO-TiO2 is explained by its reduced electron-hole recombination and visible light activity. The kinetics of photodecomposition reaction was analyzed. Antibacterial activity analysis of rGO-TiO2 nanoparticles reveals that it is more active against S. aureus than E.coli.
关键词： Titania,Antibacterial activity,Photocatalytic decomposition,Ciprofloxacin,Reduced graphene oxide
更新于2025-09-04 15:30:14