Reduced Graphene Oxide Research Articles

Ni-Co MOF Flowers/ZnO NRs Mediated Electrochemical Sensor for Rapid and Ultrasensitive Detection of Neotame in Food Samples

Abstract This study focuses on the bioreduction of waste-derived graphite rods into reduced graphene oxide(rGO), followed by the fabrication with Ni-Co metal-organic flowers and Zinc oxide nanorods(ZnO NRs) using Nafion, for sensitive detection of neotame. The Ni-Co metal-organic flowers and ZnO NRs were synthesized using solvothermal synthesis and Azadirachta indica leaf extract, respectively. Additionally, Nafion polymer enhances the stability and conductivity of the nanocomposite. The nanocomposite was characterized using UV-Vis, Fourier transform infrared spectorscopy, X-ray diffraction, Raman spectroscopy, dynamic light scattering, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray analsysis, transmission electron microscopy, and atomic force microscopy. The electrochemical studies were carried out using electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode (rGO/Nafion/Ni-Co MOF/ZnO NRs) demonstrated improved electrochemical activity (34.01µA) for neotame with an enhanced peak current at +0.73V. The LOD and LOQ values were calculated and found to be 0.32 and 0.99 µM with a recovery (%) ranging from 94.50 to 101.34%. The outcome of this study identifies the morphological and electrochemical factors as major contributors to the adsorption affinities and catalytical activities, with promising possibilities for the design of electrochemical sensing of artificial sweeteners.

Reduced graphene oxide loaded with sodium anthraquinone-2-sulfonate on functionalized carbon cloth for excellent electrochemical performance

Reduced graphene oxide loaded with sodium anthraquinone-2-sulfonate on functionalized carbon cloth for excellent electrochemical performance

Covalent Functionalisation of rGO and Nanodiamonds: Complementary Versatility and Applicability of Azomethine Ylide, Nitrile Oxide and Nitrone.

The existing synthetic protocols for the direct functionalization of carbon-based nanomaterials often entail limitations due to their harsh reaction conditions, which require the use of high temperatures for extended periods. This study aims to overcome these limitations by developing mild and efficient synthetic protocols around 1,3-dipolar cycloaddition. Beginning with the well-established azomethine ylide derivatization, we progress to the utilization of nitrile oxide, and of nitrone derivatives for the functionalization of reduced graphene oxide (rGO) as well as of nanodiamonds (NDs). This comparative work employs both classical heating and microwave activation with the aim of reducing reaction times and enhancing efficacy. Results demonstrate that nitrone can react at 60 °C and that the reaction temperature may be decreased to 30 °C with nitrile oxide. Excellent progress was made in reducing the large excess of dipoles typically required for derivatization. Nitrile oxide was proved to be the most efficient in terms of derivatization degree, while nitrone was the most versatile reagent, facilitating the decoration of the carbon nanolayer with disubstituted dihydroisoxazole. To accurately assess the degree of functionalization, the reaction products underwent characterization using various spectroscopic and analytical techniques. Additionally, an indirect evaluation of the reaction outcome was conducted through Fmoc deprotection and quantification.

Flexible solid-state supercapacitors based on biowaste-derived activated carbon and nanomaterials for enhanced performance.

Supercapacitors are energy storage devices with long cycle life that can harvest and deliver high power. This makes them attractive for a broad range of applications including flexible and lightweight wearable consumer electronics. In this work, we fabricate flexible solid-state supercapacitors with improved capacitance and cycle life. We synthesize activated carbon (AC) from cabbage leaves as a low cost, biowaste-derived active electrode material. To improve mechanical flexibility and conductivity, we incorporate reduced graphene oxide sheets (RGO) and carbon quantum dots (CQDs) into the electrodes. We show that at the optimum AC/RGO/CQD composition, the capacitance of the solid-state supercapacitor is maximized while its scan rate dependence and bending stability are simultaneously improved. We envision that this approach offers significant potential for delivering efficient energy storage devices for consumer electronics.

Pulse Dynamics in Reduced Graphene Oxide Electrolyte‐Gated Transistors: Charge Memory Effects and Mechanisms Governing the Ion‐To‐Electron Transduction

AbstractElectrolyte‐gated transistors (EGTs) are widely employed in bioelectronics due to their ability to bridge ionic and electronic phenomena in a single device. Among potential materials, reduced graphene oxide (rGO) has gained significant attention due to its ambipolar current response, quantum capacitance, and tunable conductivity. However, the rGO EGT dynamic behavior remains significantly unexplored. Here, the time‐dependent response of rGO EGTs is systematically investigated under gate voltage pulsing across different time scales (10 ms to 40 s) and amplitudes (up to |±0.8 V|). Significant charge memory is observed, particularly for long (40 s) pulses at 0.8 V, with effects also evident for shorter (1 s) and weaker stimuli (0.6 V). Multiple low‐level (0.1 V) fast pulsing (100 ms) further demonstrate charge retention post‐stimulation. All these characteristics are attributed to a complex interplay between ion entrapment within the rGO film, electrical double‐layer formation, and charge transfer processes. The stability of rGO EGTs under prolonged bias stress is also examined, aiming to contribute to the development of more robust devices. These findings revealed the complex role of electrolyte ions and electronic carriers governing the ion‐to‐electron transduction and charge memory effects in rGO EGTs, contributing to the advancement of the next‐generation bioelectronic devices.

ZnSe⊂MoSe2/rGO Petal-like Assembly as Fast and Stable Sodium Ion Storage Anodes

The development of high energy and power density sodium-ion batteries (SIBs) has attracted increasing interest in the last two decades due to the abundance and cost-effectiveness of sodium resources. Herein, this study developed a self-templating synthetic method to construct MoSe2 nanosheets which were intercalated by ZnSe nanoparticles and were anchored on the in situ reduced graphene oxide layers. The thus-fabricated composites exhibited excellent Coulombic efficiency, a remarkable rate capability and an exceptionally long cycle life when being utilized as the anode in SIBs. Specifically, a reversible capacity of 265 mAh g−1 was achieved at 20 A g−1, which could be maintained for 6400 cycles. At an ultra-high rate of 30.0 A g−1, the anode retained a capacity of 235 mAh g−1 after 9500 cycles. Such a strong performance was attributed to its unique porous structure and synergistic interactions of multi-components. The underlying sodium storage mechanism was further investigated through various techniques such as in situ X-ray diffraction spectroscopy, the galvanostatic intermittent titration method, etc. Overall, this study illustrates the great potential of clad-structured multicomponent hybrids in developing high-performance SIBs.

Hydrothermal synthesis of boron-nitrogen-sulfur tri-doped reduced graphene oxide for PEM fuel cell applications

Hydrothermal synthesis of boron-nitrogen-sulfur tri-doped reduced graphene oxide for PEM fuel cell applications

Mechanical Performance and Tribological Behavior of WC-ZrO2 Composites with Different Content of Graphene Oxide Fabricated by Spark Plasma Sintering

This paper presents research on the effects of the addition of various contents of graphene oxide and sintering temperature on the mechanical, tribological, and electrical characteristics of WC-ZrO2 composites. Wet processing and spark plasma sintering provided dense samples with simultaneous reduction of graphene oxide (rGO) during sintering. The obtained results showed that the best mechanical properties were observed at a sintering temperature of 1700 °C in samples with 0.5 vol.% rGO content; namely, indentation fracture toughness (5.8 ± 0.4 MPa·m1/2) and flexural strength (872 ± 43 MPa) increased by 9% and 24.3% compared with the sample without rGO. In addition to improved mechanical performance, rGO-reinforced composites exhibited lower wear rates and friction coefficients than non-rGO composites, due to the formation of a graphitic lubricating tribolayer on worn surfaces and counterbodies in a friction pair, which provided sufficient lubrication to reduce the coefficient of friction and wear rate. The resulting composites also showed low electrical resistivity, suggesting the possibility of using electrical discharge machining to manufacture ceramic products of complex shapes from them.

Lithium Storage Mechanisms and Electrochemical Behavior of a Molybdenum Disulfide Nanoparticle Anode

This study investigates the electrochemical behavior of molybdenum disulfide (MoS2) as an anode in Li‐ion batteries, focusing on the extra capacity phenomenon. Employing advanced characterization methods such as in situ and ex situ X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, and transmission electron microscopy, the research unravels the complex structural and chemical evolution of MoS2 throughout its cycling. A key discovery is the identification of a unique Li intercalation mechanism in MoS2, leading to the formation of reversible LixMoS2 phases that contribute to the extra capacity of the MoS2 electrode. Density function theory calculations suggest the potential for overlithiation in MoS2, predicting Li5MoS2 as the most energetically favorable phase within the lithiation–delithiation process. Additionally, the formation of a Li‐rich phase on the surface of Li4MoS2 is considered energetically advantageous. After the first discharge, the battery system engages in two main reactions. One involves operation as a Li‐sulfur battery within the carbonate electrolyte, and the other is the reversible intercalation and deintercalation of Li in LixMoS2. The latter reaction contributes to the extra capacity of the battery. The incorporation of reduced graphene oxide as a conductive additive in MoS2 electrodes notably improves their rate capability and cycling stability.

Expression of concern: Plasmonic photothermal destruction of uropathogenic E. coli with reduced graphene oxide and core/shell nanocomposites of gold nanorods/reduced graphene oxide.

Expression of concern for 'Plasmonic photothermal destruction of uropathogenic E. coli with reduced graphene oxide and core/shell nanocomposites of gold nanorods/reduced graphene oxide' by Kostiantyn Turcheniuk et al., J. Mater. Chem. B, 2015, 3, 375-386, https://doi.org/10.1039/C4TB01760A.

A Study on Gas‑sensing Behavior of Reduced Graphene Oxide (rGO) Green Method, Enhansing the Performance of Green-synthesized Reduced Graphene Oxide

This paper presents a comparative study on gas-sensing behavior of reduced graphene oxide (rGO) synthesized by chemical and green synthesis route. GO is synthesized by Hummers method and then reduced employing two reducing agents hydrazine hydrate [represented by (rGO)1] and L-citrulline [represented by (rGO)2]. Synthesized products were then obtained in the form of thin films, and tested for 10 ppm NO2 and CO at operating temperatures of 50, 100, and 150 °C. The green-synthesized reduced graphene oxide (rGO)2 exhibits higher relative response of 254.7% as compared to conventionally synthesized (rGO)1 (93.9%) and GO (22.7%) for 10 ppm NO2 at operating temperature of 150 °C. Furthermore, a switching of conductivity from usual p-type behavior to n-type on exposure of NO2 is observed at all operating temperatures (50, 100, and 150 °C) for GO, (rGO)1, and (rGO)2. The XRD, FTIR, and Raman confirm the oxidation and reduction process. (rGO)2 shows high thermal stability as observed through TGA. FESEM and TEM images show wrinkled sheet structure for GO as well (rGO)1 and (rGO)2. The data observed from the characterization of resultant products have made it possible to explain better reduction of GO through green-reducing agent and enhanced gas-sensing performance of green-synthesized reduced graphene oxide.

Expression of concern: Selective isolation and eradication of E. coli associated with urinary tract infections using anti-fimbrial modified magnetic reduced graphene oxide nanoheaters.

Expression of concern for 'Selective isolation and eradication of E. coli associated with urinary tract infections using anti-fimbrial modified magnetic reduced graphene oxide nanoheaters' by Fatima Halouane et al., J. Mater. Chem. B, 2017, 5, 8133-8142, https://doi.org/10.1039/C7TB01890H.

Expression of concern: Reduced graphene oxide nanosheets decorated with AuPd bimetallic nanoparticles: a multifunctional material for photothermal therapy of cancer cells.

Expression of concern for 'Reduced graphene oxide nanosheets decorated with AuPd bimetallic nanoparticles: a multifunctional material for photothermal therapy of cancer cells' by Gitashree Darabdhara et al., J. Mater. Chem. B, 2015, 3, 8366-8374, https://doi.org/10.1039/C5TB01704A.

Exploring the structural, optical, magnetic, and antibacterial characteristics of hydrothermally synthesized α-Fe2O3/rGO nanocomposites

Abstract Hematite (α-Fe2O3) and its composites have garnered significant interest due to their outstanding features, making them promising candidates for a wide range of applications in photocatalysis, water splitting, gas sensing, and antibacterial fields. This study describes the synthesis of hematite and reduced graphene oxide (rGO) nanocomposites via a facile hydrothermal method, producing three samples using 0.018 g (FG1), 0.036 g (FG2), and 0.072 g (FG3) of graphene oxide (GO). The prepared nanopowders were subjected to versatile characterizations for studying their morphological, structural, optical, and magnetic characteristics. The growth of the rhombohedral structure of hematite was confirmed by analyzing x-ray diffraction patterns, and the production of nanocomposites was verified by Raman and infrared spectroscopy. According to electron microscope images, increasing the content of GO in the precursor solution caused the change of the morphology from large rhombus and cubic shapes with sizes of about 180 nm to worm-like nanoparticles with a length of about 90 nm and a mean diameter of 25 nm. The magnetic hysteresis loops of the composite samples reflect their ferromagnetic characteristics, with saturation magnetization (Ms) values of 0.02235, 0.14990, and 0.0608 emu g−1 for FG1, FG2, and FG3 samples, respectively. Lastly, the antibacterial activity of the nanocomposites was screened against both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria, and the results indicated that the growth of both bacterial strains was inhibited by all synthesized nanoparticles.

Comparative study of reduced graphene oxide (rGO) synthesis using methanol extracts of Camellia sinensis: A green approach

Comparative study of reduced graphene oxide (rGO) synthesis using methanol extracts of Camellia sinensis: A green approach

Heterogeneous catalysts for electro-Fenton degradation of cytostatic drug cytarabine

In the present work, a reduced graphene oxide (rGO) modified-Fe3O4 doped bifunctional carbon felt cathode (rGO-Fe3O4/CF) that is capable of generating and converting H2O2 into hydroxyl radicals (•OH) on-site was fabricated, thus removing the need for an external catalyst. In addition, an rGO-modified cathode (rGO/CF) with high H2O2 production efficiency and a heterogeneous Fenton catalyst (CNT-Fe3O4) with magnetic properties were fabricated. The study examined the degradation and mineralization of the cytostatic drug cytarabine (CYT) using two HEF configurations: (i) a bifunctional cathode rGO-Fe3O4/CF and (ii) a combination of the rGO/CF cathode with CNT-Fe3O4 catalyst. The effects of parameters such as catalyst concentration, initial pH, and applied current were studied. HPLC and ion chromatography analyses were used to identify carboxylic acids and inorganic end-products, respectively. The results show that 0.1 mM CYT was completely degraded within 18 min at an applied current of 300 mA in the HEF system with the rGO-Fe3O4/CF bifunctional cathode. Total organic carbon (TOC) analysis revealed that the bifunctional cathode system achieved 98.2% mineralization of CYT after 4 h of treatment at 300 mA. Using the rGO/CF cathode and CNT-Fe3O4 catalyst cell, total degradation of 0.1 mM CYT occurred within 7 min, and nearly total mineralization (97.3% TOC removal) was achieved at 300 mA after 4 h.

Gelatin-reduced graphene oxide-azithromycin biocomposite coating on baghdadite scaffolds

A critical bone tissue engineering (BTE) strategy is fabricating porous scaffolds using simple and straightforward techniques. However, all porous structures share a common drawback, reduced strength due to porosity. Furthermore, bone scaffolds are vulnerable to bacterial infections when implanted, especially in compromised bone conditions. In this study, baghdadite (BAGH) scaffolds were developed and coated with gelatin (Gel)-reduced graphene oxide (RGO)-azithromycin (AZM) with suitable porosity (75–80%) and pore size (600–800 μm) using the space holder method, combined with a dip coating process in a low vacuum condition. The outcomes revealed that incorporating the Gel-RGO layer increased the compressive strength from 0.8 to 2.9 MPa for the Gel-RGO-AZM scaffolds. The scaffolds coated with Gel-RGO-AZM demonstrated improved bioactivity compared to their uncoated counterparts, showcasing the ability to generate hydroxyapatite (HA)-like crystals after a 28-day soaking period in simulated body fluid (SBF). In vitro studies validated the antimicrobial effectiveness of co-released RGO and AZM from Gel-RGO-AZM coated scaffolds against E. coli and S. aureus bacteria. Moreover, the coated scaffolds exhibited significantly improved cellular responses. In conclusion, the research results show that the developed BAGH scaffolds coated with Gel-RGO-AZM are promising materials for BTE, offering enhanced compressive strength, bioactivity, biocompatibility, and antibacterial performance.

The Synthesis, Characterization, and Theoretical Study of Ruthenium (II) Polypyridyl Oligomer Hybrid Structures with Reduced Graphene Oxide for Enhanced Optoelectronic Applications.

π-conjugated polymers are arguably one of the most exciting classes of materials and have attracted substantial attention due to their unique optical and electronic properties. The introduction of transition metals into conjugated polymers tunes the optoelectronic properties of these metallopolymers, which may improve their performance in device applications. Graphene and reduced graphene oxide (RGO) derivatives are interesting materials with a unique structure and outstanding properties. The present work reports an investigation of three hybrid RGO and π-conjugated oligomers that contain ruthenium polypyridyl chromophores serving as models to provide molecular-level insight for the corresponding transition-metal-containing conjugated polymers.

A Universal Strategy for Synthesis of Large-Area and Ultrathin Metal Oxide/rGO Film Towards Scalable Fabrication of High-Performance Wearable Microsupercapacitors.

High-performance wearable microsupercapacitor (MSC) as energy storage components is highly desirable for developing self-powering wearable electronics. However, synthesis of MSC electrode film concurrently possessing large area, ultrathin thickness, and high areal energy storage capability is still challenging. Herein, a universal strategy is reported to synthesize large-area and ultrathin metal oxide nanoparticles (MONPs)/reduced graphene oxide (rGO) hybrid-structured films by attaching self-assembled film of a wide range of MONPs onto self-assembled rGO film and subsequent carbonization. Combining a template-assisted patterning strategy and a floating film salvaging process, flexible symmetric and asymmetric MSCs based on MONPs@C/rGO films can be easily prepared in large areas. MONP agglomeration is avoided and its pseudocapacitive behavior is well utilized, thereby realizing a high areal specific capacitance of 9.32 mF cm-2 in Fe3O4@C/rGO-based symmetric MSC at a film thickness of only 275 nm, corresponding to a high volumetric specific capacitance of 338.9 F cm-3. Moreover, the MnO@C/rGO‖Fe3O4@C/rGO-based asymmetric MSC delivers a high volumetric energy density of 69.8 mWh cm-3. The MSCs also demonstrate their efficient power supply in wearable self-powering systems. This work provides a new route for scalable preparation of high-performance wearable MSCs, and also enables customizable fabrication and performance tuning of MSCs.

High-Precision Fluorescence Platform for Point-of-Care Measurements of Low-Density Lipoprotein Based on Nitrogen, Sulfur-Doped Graphene Quantum Dots and Ferric Tetroxide @ Reduced Graphene Oxide

High-Precision Fluorescence Platform for Point-of-Care Measurements of Low-Density Lipoprotein Based on Nitrogen, Sulfur-Doped Graphene Quantum Dots and Ferric Tetroxide @ Reduced Graphene Oxide