Reduced Graphene Oxide Hybrid Research Articles

GREEN SYNTHESIS OF MAGNETIC REDUCED GRAPHENE OXIDE HYBRID NANOCOMPOSITE USING NOVEL CLERODENDRUM PANICULATUM FOR THE REMOVAL OF MB DYE AND Cd (II) FROM AQUEOUS SOLUTION VIA MAGNETIC SEPARATION

The utmost dangerous and significant source of environmental contamination is constituted by ionic dyes and heavy metals. Graphene oxide (GO) can eradicate heavy metal ions and dyes from effluent, but the major difficulty associated with GO is the inconvenience during separation. In this study, magnetic reduced GO (rGO-Fe3O[Formula: see text] hybrid nanocomposite is synthesized by using the novel green reducing agent and is used as an adsorbent for the removal of methylene blue (MB) dye and Cd (II) ions. The prepared samples are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and FTIR spectroscopy. adsorption study of rGO-Fe3O4 is carried out using UV visible spectrophotometry and it is obtained that the maximum adsorption capacity in the mono component system using double distilled water for MB dye and Cd (II) ions is 64.52 and 93.49[Formula: see text]mg/g, respectively. Moreover, the effect of different parameters such as temperature, adsorbent dosage, contact time, pH and initial adsorbate concentration on the adsorption of heavy metal and dye is investigated.

Multi-compartmentalized electrochemical sensing platforms for monitoring cascade enzymatic reactions

Designing an electrochemical biosensor with the required features is a complex process involving multiple factors. For instance, nanocomposite materials used ensure the adaptation of the sensor to specific parameters on demand. But beyond making more versatile sensors, these materials likely offer excellent sensing platforms to mimic biological processes (e.g. cell communication) on the electrode surface. For this, developed methods are needed to integrate non-conductive nanoreactors for molecular communication into a biocompatible matrix on electrode surfaces with the request of spatially separated and controlled enzyme localization. Here, we present a novel reduced graphene oxide hybrid material to immobilize polymeric nanoreactors supported by an alginate network as a matrix on the electrode surface. The possibility of introducing cascade reactions in an electrochemical biosensor has the advantage of broadening the target substrates as well as their selectivity using enzymes in different nanocompartments (=compartmentalization). The polymeric vesicles allow the loading of enzymes or artificial enzymes, offering active center retention and long-term enzyme stability. Firstly, the inclusion of spatially separated polymeric active nanocompartments into the matrix on the electrode surface is used to monitor a simple enzyme reaction. However, the study’s accomplishment lies in its successful ability to monitor an enzyme cascade reaction, one producing and the other consuming hydrogen peroxide, hosting natural and artificial enzymes. This proof-of-concept generates an important contribution to the design of analytical platforms capable of detecting complex environments or even monitoring communication between cell-like structures, extremely useful for fields such as synthetic biology, biomimetics and advanced biosensors.

Nitrogen, sulfur coordinated metal complex and reduced graphene oxide hybrid materials as counter electrodes for application in dye-sensitized solar cells

Graphene, as one of the carbon-based materials, is considered to be a potential replacement for platinum and has been widely used as a counter electrode in dye-sensitized solar cells to achieve low-cost and high electrocatalytic materials. In this work, we synthesized a nitrogen-sulfur-coordinated iron complex as a source of heteroatoms, and prepared iron-nitrogen-sulfur co-doped reduced graphene oxide (FeNS-rGO) composite material by mixing with different mass ratios of graphene oxide (GO) and thermal annealing under nitrogen at 400 °C. The sintered GO was transformed into rGO, which increased the conductivity of materials, while the doping of nitrogen and sulfur atoms enhanced the carrier mobility and conductivity of the material. The distribution of Fe on graphene also improved the catalytic performance of material. FeNS-rGO (5:1), used as the CE in DSSC, showed superior reduction catalytic activity for I−/I3− compared to platinum and demonstrated an excellent power conversion efficiency of 8.17 %, which outperformed platinum. This proves that the graphene composite material doped with iron, nitrogen, and sulfur has excellent performance and can be used as a substitute for platinum.

Sensitive electrochemical biosensor for bisphenol A based on laccase immobilized on polypyrrole‐3‐carboxylic/Sb2O5/reduced graphene oxide hybrid nanomaterial

AbstractAn electrochemical biosensor for the bisphenol A determination was constructed onto a glassy carbon electrode modified with a hybrid nanostructure based on polypyrrole‐3‐carboxylic acid/Sb2O5/reduced graphene oxide and laccase enzyme. The hybrid nanostructure was characterized by X‐ray photoelectron spectroscopy (XPS), HR‐TEM, SEM microscopy, and electrochemical techniques. The biosensor displayed excellent response for bisphenol A determinations by differential pulse voltammetry, showing a theoretical detection limit of 9.9 nmol L−1 in the linear range of 0.1–1.0 μmol L−1. The biosensor demonstrated excellent selectivity in the determinations of bisphenol A in tap water without significant interference from other species, such as 17β‐estradiol, Estriol, Progesterone, Catechol, Hydroquinone, Ascorbic acid, and Dopamine. The biosensor also has presented an excellent performance in bisphenol A determinations in water, with recovery tax ranging from 99.6 to 101 %. Therefore, it can be used satisfactorily to detect bisphenol A in real samples.

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe2-Reduced Graphene Oxide Hybrid

Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe₂-Reduced Graphene Oxide Hybrid

Photocatalytic Degradation Studies of Organic Dyes over Novel Cu/Ni Loaded Reduced Graphene Oxide Hybrid Nanocomposite: Adsorption, Kinetics and Thermodynamic Studies.

Nowadays, for environmental remediation, photocatalytic process involving graphene-based semiconductors is considered a very promising oxidation process for water treatment. In the present study, nanocomposite (Cu/Ni/rGO) has been synthesized by Dypsis lutescens leaf extract. Characterization of the sample was carried out by UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Different parameters like contact time, nanocatalyst amount, dye concentration, effect of temperature. and pH factor were optimized to examine the maximum removal efficiency for dyes rhodamine B and alizarine R with and without visible light source. In both cases, i.e., with or without light, maximum removal was observed at 20 mg of nanocatalyst for 5 ppm concentration of both dyes at 45 °C temperature and pH 10 for rhodamine B and pH 4 for alizarine R, respectively with a 20 min contact time. Maximum removal of dyes 93% rhodamine B and 91% alizarine R were observed under a tungsten lamp as compared to without a tungsten lamp, i.e., 78% of RhB and 75% of AR from mixture solution of these dyes. To assess the rate of reaction, spontaneity, and nature of reaction thermodynamics, kinetics and adsorption isotherms were studied. Thermodynamic values indicated that both dyes depicted endothermic and spontaneous degradation processes. Isotherm data fitted best to a Freundlich isotherm, while results of kinetic studies of both dyes followed the pseudo 2nd order kinetic equation. In the end, scavenging radical studies concluded that hydroxyl radicals were the main active specie involved in the photocatalytic degradation process, and regeneration experiments resulted that Cu/Ni/rGO nanocomposites were re-utilized for about four times.

Co-electrodeposition hybrid reduced graphene oxide and nickel-cobalt selenide nanosheets on silicon nanowires for high-performance supercapacitor

Due to inherent compatibility with IC technology, 3D silicon is prone to build a skeleton for the energy storage electrodes. Herein, a unique 3D hierarchical core-shell electrode was first developed with silicon nanowire arrays (SiNWs), metal selenide (TMSe) and reduced graphene oxide (RGO) nanosheets, where SiNWs decorated with Ni particles (Si/Ni) served as the conductive core and co-electrodeposited hybrid nickel-cobalt selenide (NCSe) and RGO nanosheets (NCSe-RG) functioned as the high capacitive outer shell. Owing to the synergy effect between NCSe and RGO, high-speed electron transport channels of Si/Ni, and abundant electroactive sites of porous NCSe layer, the synthesized Si/Ni/NCSe-RG electrode delivered a large capacitance of 2268 F g−1 (1973 mF cm−2) at 1 A g−1 which was higher than most reported silicon-based electrodes, and an excellent rapid-charging capability (1540 F g−1 at 30 A g−1). Furthermore, a solid asymmetric supercapacitor (SC) was prepared by using Si/Ni/NCSe-RG as the positive electrode, demonstrating an excellent energy density of 53.23 Wh kg−1 at the power density of 800 W kg−1. Our results suggest that high-performance SC electrodes can be engineered with TMSe and 3D silicon with a simple and time-saving method.

3D porous alumina/graphene hybrids prepared by atomic layer deposition and their performance for water treatment

Metal / carbon hybrids have impressive potential of applications in many fields: catalysis, energy conversion and storage, environmental. However, further efforts are needed to achieve a better control of homogeneity of the metal oxide deposit on the carbon surface to provide reliable synthesis approaches of metal / carbon hybrids. In this work, atomic layer deposition is used to prepare 3D porous alumina / reduced graphene oxide hybrid monoliths. We show that atomic layer deposition, even though rarely reported to prepare metal oxide / carbon hybrids, allows a conformal coating onto the graphene nanosheet surface. In-depth advanced characterization have been performed thanks to a coupled approach consisting of the preparation of lamellas of the porous hybrid by means of focused ion beam and their analysis by transmission electron microscopy. A good accessibility of the alumina precursors to the internal surface of the prepared 3D porous carbon monoliths was evidenced. The alumina / graphene hybrid prepared with 50 cycles of ALD deposit has a surface as high as 284 m2/g. As a proof-of-concept for the interest of the designed hybrids, they are tested for the removal of Congo red, a standard organic dye pollutant. 87 and 98 % of Congo red removal were reached at the first and the second step of adsorption proving the good adsorption performance and reusability ability of the de designed hybrid adsorbents. We believe that such multi-porous 3D alumina / graphene macrostructures that offers a favorable accessibility to the adsorption sites open interesting potentialities for pollution remediation applications.

Hybrid rGO-AgNPs Conductive Ink for Inkjet Printed Flexible Humidity Sensor

Due to the challenging dispersion of graphene in aqueous media, organic solvents are commonly used in conductive graphene inks. This will result in safety issues and environmental pollution. In this study, we demonstrated a green approach of graphene ink preparation through one-pot synthesis reaction that produce a hybrid reduced graphene oxide (rGO)-silver nanoparticles (AgNPs), with deionized water as solvent. The synthesized rGO-AgNPs was monitored using ultraviolet–visible (UV-Vis) spectroscopy and fourier transform infrared (FTIR). A stable dispersion of rGO-AgNPs ink was confirmed through UV-Vis analysis. FTIR result showed the removal and the reduction in the intensities of absorption bands of oxygen-containing functional groups, which indicated that graphene oxide (GO) has been successfully reduced to rGO in the hybrid ink. The printed film of rGO-AgNPs exhibited a high conductivity of 1.50 × 104 S/cm, proven that the electrical performance of the hybrid ink has been improved as compared to previously reported GO-based ink. Printed into interdigitated electrode (IDE), the impressive characteristic of our hybrid ink performed well as a high-sensitivity flexible humidity sensor.

The synergy of Pd nanoparticles and oxygen vacancy to modulate SnO2 modified reduced graphene oxide hybrids for room-temperature ppb-level NO2 detection

Reduced graphene oxides (RGO)-based materials exhibit high carrier mobility and selective recognition ability to NO2, making them constitute promising platform for room-temperature NO2 detection. However, the low sensitivity becomes the main bottleneck for their further development. Here, we demonstrate that synergy of Pd nanoparticles (NPs) and oxygen vacancies can modulate the surface active sites over SnO2 NPs modified RGO hybrids (labeled as SR), leading to improving the sensitivity of room-temperature NO2 sensors. Experimentally, a wet-chemical method was used to introduce oxygen vacancies onto SR, leading to forming SR with rich oxygen vacancies (labeled as SR-Vo), which were subsequently deposited with Pd NPs, resulting in preparing Pd NPs loaded SR-Vo hybrids (labeled as Pd-SR-Vo). Impressively, the response value to 1 ppm NO2 of Pd-SR-Vo hybrids reaches to 9.8, which is much higher than that of R-Vo hybrids (5.6) and SR hybrids (3.3). The improvement of sensitivity toward NO2 for Pd-SR-Vo hybrids is attributed to the synergy effect of Pd NPs and oxygen vacancies, including shortening the band gap of Pd-SR-Vo hybrids with raising conduction band level, widening the width of electron depletion layer between SnO2-Vo and RGO, introducing Schottky contact between Pd and SnO2-Vo, improving efficiency for gas sensing reaction. This work not only provides an efficient approach to fabricate high-performance NO2 sensors, but also opens a new avenue for sensing materials design and modification.

Synergistic effect of hybrid reduced graphene oxide (rGO) and carbon nanotubes (CNTs) reinforcement on microstructure, mechanical and biological properties of magnesium-based composite

Magnesium (Mg) was considered as a new kind of biomaterial implant due to its biodegradability and biocompatibility. Nevertheless, sufficient mechanical properties and low degradation rates in physiological environments are required. In this research, we have demonstrated that a network structure is developed from the reduced graphene oxide (rGO) and carbon nanotubes (CNTs), which inhibited face-to-face aggregation of rGO nano-platelets by straight CNTs inserted into adjacent rGO nano-platelets. The combination of rGO and CNTs was then used to strengthen the Mg-based nanocomposite fabricated using semi-powder metallurgy. The compressive strength and strain to fracture were maximally achieved 326.7 MPa and 11.58%, respectively for composite with 0.16 wt% CNTs and 0.5 wt% rGO. It was due to the effective load transfer and energy absorption of rGO and CNTs. Mechanisms for crack tip shielding, crack bridging and crack deflection was found to be responsible for mechanical enhancement. The electrochemical tests showed that the composite with the lowest CNTs concentration has the best corrosion resistance. In addition, the apatite-forming ability of composite in simulated body fluid (SBF) and cell culture experiments demonstrated favorable composite bioactivity and biocompatibility. Evaluation of the antibacterial activity showed that the growth and penetration of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria could be significantly inhibited with increasing rGO-CNTs hybrid content in Mg alloy. This study may open the doors to the fabrication of Mg-based nanocomposite implants containing rGO-CNTs hybrid fillers for load-bearing applications.

Synthesis of V2O5 Nanoribbon–Reduced Graphene Oxide Hybrids as Stable Aqueous Zinc-Ion Battery Cathodes via Divalent Transition Metal Cation-Mediated Coprecipitation

Aqueous zinc-ion batteries (AZIBs) are an emerging sustainable and safer technology for large-scale electrical energy storage. Here, we report the synthesis of hybrid materials consisting of V2O5 nanoribbons (NRs) and reduced graphene oxide (rGO) nanosheets as AZIB cathode materials by divalent metal cation-mediated coprecipitation. The divalent metal ions M2+ (Zn2+ and Mn2+) effectively neutralize the negative charges on the surface of microwave-exfoliated crystalline V2O5 NRs and graphene oxide (GO) nanosheets to form a strongly bound assembly. After thermal annealing in a nitrogen atmosphere, GO is converted into rGO with higher electrical conductivity while the layers in V2O5 NRs are expanded by M2+ intercalation. When only Zn2+ ions are used during coprecipitation, the produced Zn-V2O5 NR/rGO hybrid shows a very high reversible specific capacity of ∼395 mAh g–1 at 0.50 A g–1 but suffers from poor stability. This is improved by mixing Mn2+ with Zn2+ ions during coprecipitation. The (Mn + Zn)-V2O5 NR/rGO hybrid shows a slightly lower specific capacity of ∼291 mAh g–1 at 0.5 A g–1 but a substantially improved long-cycling stability and better rate performance due to the stronger binding of Mn atoms in the V2O5 host that serve as stable pillars to support the expanded V2O5 layers.

Synthesis of High-Efficiency, Eco-Friendly, and Synergistic Flame Retardant for Epoxy Resin

It remains a challenge to prepare flame-retardant composites via the addition of a low content of flame retardant. In this work, a novel DOPO-functionalized reduced graphene oxide hybrid (DOPO-M-rGO) flame-retardant system was synthesized for epoxy resin (EP). The phosphorus-nitrogen-reduced graphene oxide ternary synergistic effect provided DOPO-M-rGO with high flame-resistance efficiency in EP; thus, the EP-based composite exhibited superior fire-resistant performance at extremely low DOPO-M-rGO loading. The limiting oxygen index (LOI) of the EP-based composite was increased from 25% to 32% with only 1.5 wt% DOPO-M-rGO addition, and the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) were significantly decreased by 55%, 30%, and 20%, respectively. In addition, as a halogen-free flame-retardant system, DOPO-M-rGO presents great application potential as an eco-friendly additive for the flame-resistance improvement of thermosetting polymer materials.

A ternary oxygen-vacancy abundant ZnMn2O4/MnCO3/nitrogen-doped reduced graphene oxide hybrid towards superior-performance lithium storage.

Transition metal oxides (TMOs) and metal carbonates exhibit high specific capacity, abundant reserves on Earth, and environmental friendliness as anode materials for lithium-ion batteries (LIBs). However, their poor electrical conductivity and serious volume expansion lead to rapid capacity decay. Herein, a stable and highly conductive composite of an oxygen-vacancy abundant nitrogen-doped reduced graphene oxide (NG) encapsulated ZnMn2O4/MnCO3 (ZnMn2O4/MnCO3/NG) hybrid is successfully fabricated, which can provide more spaces for rapid ion diffusion and corroborate fast electron transport. The ZnMn2O4/MnCO3/NG hybrid exhibits an incredible reversible capacity (916 mA h g-1 at 0.1 A g-1), preeminent cycling stability (800 mA h g-1 at 1 A g-1 after 300 cycles) and outstanding rate capability (459 mA h g-1 at 2 A g-1). The excellent lithium storage performance of ZnMn2O4/MnCO3/NG is attributed to the synergistic effect between ZnMn2O4 and MnCO3, the addition of nitrogen and oxygen defects, and the stable structures of NG, which relieve the volume expansion of the electrode material, improve the electronic conductivity and enhance structural stability and surface capacitive response. This work provides a new idea for constructing oxygen-vacancy abundant NG encapsulated bimetal oxides for energy storage of LIBs.

Hybrid reduced graphene oxide nanosheets with negative magnetoresistance for the diagnosis of hypoglycemia.

Few glucometers are available to easily and quickly measure low blood glucose levels (≤4 mmol L-1) from a small amount of blood samples. Here, a hybrid reduced graphene oxide (rGO)-based magnetoresistance (MR) sensor has been developed to monitor blood glucose levels to quickly detect hypoglycemia. Hybrid rGO nanosheets, incorporating Fe50Co50 nanoparticles onto rGO nanosheets, with an unusual large negative MR (-5.7%) at room temperature under a small magnetic field (9.5 kOe) have been successfully fabricated through a one-pot reaction. To quickly detect the low concentration of glucose in a small amount of blood (1 μL), a two-step process has been further developed by using the "sandwich" structural MR sensor. The results show that the higher the negative MR value of the sensor, the lower the concentration of glucose that can be detected. A linear relationship between the MR and the concentration of the spiked plasma glucose taken from streptozotocin-induced diabetic rats can be found when the concentration of glucose is in the range of 0-6 mmol L-1. The limit of detection (LOD) of this MR glucose sensor is 0.867 mmol L-1. The accuracy of the rGO-based MR sensor is improved in measuring low concentration of plasma glucose as compared to that of a commercialized glucometer. Furthermore, the selectivity of the rGO-based MR sensor has been studied. The results demonstrate that the rGO-based MR sensor is a flexible and sensitive detection platform and specifically suitable for monitoring low concentrations of plasma glucose to prevent from hypoglycemia.

Active-site-rich binary metal oxides integrated organic–inorganic hybrid nanocomposite: Electrochemical simultaneous detection of multi-drugs of isoprenaline and resorcinol in real samples

In recent years, awareness on human health is increasing, which also increased the use of drugs to efficiently cure or halt the disease. Besides their certain beneficiary effects, it also triggers some alarming conditions in the body when the drug crosses a certain limit. Therefore, there is a need to develop efficient methods to detect the amount of the drug in the human body. In this work, for the first time, we developed a novel zinc manganate incorporated on polydopamine encapsulated reduced graphene oxide hybrid nanocomposite (rGO-pDA-ZnMnO3 HNC) efficient electro-catalyst for the simultaneous electrochemical detection of multi-drugs of Isoprenaline (IP) and Resorcinol (RC). The incorporation of the ZnMnO3 on rGO-pDA sheets indicates excellent conductivity due to its enhanced active sites and high surface area. The rGO-pDA-ZnMnO3 HNC was drop-casted on the surface of GCE and used as a superior electro-catalyst for individual and simultaneous detection of multi-drugs using CV and DPV. The DPV results showed excellent electrochemical performance, like IP and RC in linear ranges (LR) of 0.004 – 85.99 and 0.04 – 27.9 µM and lower limit values (LOD) of 3.1 and 7.1 nM, respectively. Further, the modified GCE has excellent interference capability, repeatability, and stability. Finally, the practical impact was demonstrated in real-time samples of human urine, tap water, and hair dyes. Remarkably, the recovery rate of IP and RC is ∼99 % and ∼98 %, respectively with RSD of less than 3 %, which authenticates the usefulness of the proposed sensor for real-time applications.

Cellulose nanocrystal regulated ultra-loose, lightweight, and hierarchical porous reduced graphene oxide hybrid aerogel for capturing and determining organic pollutants from water

The ultra-loose and lightweight reduced graphene oxide/cellulose nanocrystal (rGO/CNC) hybrid aerogel was developed by hydrothermal method. Owing to the dispersibility and plentiful chemical groups of CNC, a variety of rGO/CNC hybrid aerogels with tunable dimensions were formed, thereby overcoming the limitation of size control of rGO aerogels by hydrothermal treatment. Moreover, rGO/CNC hybrid aerogel was endowed with ample functional groups, ultra-loose structure, and abundant micro/meso-pores, which allowed the composite exhibit excellent performance for capturing organic pollutants. With the use as solid-phase microextraction (SPME) coating to extract and determine polycyclic aromatic hydrocarbons (PAHs), the rGO/CNC composites presented superior extraction capacities for PAHs than pristine rGO and commercial SPME coatings due to the synergistic effects of π-π stacking, chemical groups bonding, and fast internal transfer in thick rGO/CNC layers. The proposed analytical method presented good linearity (R2 ≤ 0.9988) in concentration of 0.1–2000 ng L−1, low limits of detections (0.012–0.076 ng L−1), and excellent reproducibility. Finally, the proposed method was applied to determine PAHs from real water, and obtained satisfactory recoveries. This study proposed a novel method for regulating rGO aerogel structures, and confirmed its effectiveness for efficiently capturing organic pollutants from water.

Highly stable polyaniline array@ partially reduced graphene oxide hybrid fiber for high-performance flexible supercapacitors

The development of flexible supercapacitors (SCs) with high energy density, excellent deformation and cycling stability has great meaning for flexible electronic. Herein, polyaniline array@carbon nanotubes/partially reduced graphene oxide hybrid fiber (PANI@CNT/PRGO) was rationally designed and fabricated. The PANI array were vertically and uniformly grown on CNT/PRGO fiber by controlling the nucleation sites on the fiber. This unique structure enabled the ion to rapid diffusion and the electron to fast transport and sufficient utilization of active sites. The strong interfacial interaction between PANI and CNT/PRGO fiber can reduce the risk of PANI shedding from the fiber during mechanical deformation and long-term cycling. As a consequence, a fiber-shaped SC fabricated by PANI@CNT/PRGO fiber can deliver high volumetric capacitance of 50.2 F cm−3 at a current density of 60 mA cm−3 with 62.5% capacitance retention at 2000 mA cm−3. More encouragingly, the device not only possesses outstanding flexibility and deformation stability (Retention 96.6% after 2000 bending cycles) but also owns prominent long-term stability (Retention 95.8% after 20,000 cycles). Furthermore, the device can yield an outstanding energy density up to 6.97 mWh cm−3. This findings may carve out a new path for regulating the nucleation sites to control the distribution of nanomaterials on graphene fiber, thus obtain hybrid fiber electrodes with outstanding electrochemical performances.

Rational synthesis of reduced graphene oxide hybrid nanocomposite with iron tungstate for selective detection of epinephrine in biological fluids

Hybrid nanocomposites made from metal tungstate and stacked graphene nanosheets have attracted the curiosity of researchers due to their high conductivity, strong electrochemical activity, and quick electrochemical transfer response. These properties prompted us to employ co-precipitation and sonochemical approaches to create low-cost iron tungstate (FeWO4)/reduced graphene oxide (rGO) hybrid material. The as-synthesized FeWO4/rGO nanocomposites (NCs) were evaluated for their physicochemical properties and structural and morphological aspects. A modified electrode composed of FeWO4/rGO NCs was utilized to detect epinephrine (Eph), a significant neurotransmitter and hormone associated with various human activities. The electrochemical behavior of Eph was quantified using cyclic voltammetry, and differential pulse voltammetry (DPV) on a FeWO4/rGO NCs modified electrode. According to the DPV study, Eph concentration was linearly distributed from 0.05 to 990.5 µM. For determining Eph, the sensor had a detection limit of 0.0073 µM and a sensitivity of 5.857 µAµM−1 cm−2. The sensor displayed excellent recovery results for the determination of Eph in the human urine and epinephrine pills real samples, revealing its excellent practicality.

Three-Dimensional Reduced Graphene Oxide Hybrid Nano-Silver Scaffolds with High Antibacterial Properties.

In recent years, hazardous wastewater treatment has been a complex and global problem. In this work, by considering the antimicrobial activity of Ag nanoparticles (AgNPs) and reduced graphene oxide (rGO), we constructed an antibacterial device (G-AgNP) with AgNPs conformably deposited onto a 3D scaffold of reduced graphene oxide in situ. The major limitation, which is difficult to recycle, of two-dimensional graphene-silver composite materials in previous studies is improved. Characterization techniques, SEM, TEM, XRD, and XPS, confirmed the synthesis of nanocomposites. Attributed to its larger specific area, more active sites, and synergistic enhancement, the G-AgNP device demonstrated the best bacterial removal capacity, with an antibacterial rate for both E. coli and S. aureus as high as 100% at quite low AgNP contents. The reported G-AgNP has potential application as a wearable sewage treatment device and for the protection of wearable sensors as a promising sterilizing candidate based on its high and stable antibacterial efficiency.