Reduced Graphene Oxide Research Articles

Molecular imprinting sensor based on zeolitic imidazolate framework derived Co, N-doped carbon loaded on reduced graphene oxide toward the determination of dopamine.

Anovel voltammetric sensor designed for dopamine(DA) detectionis presented utilizing a combination of zeolitic imidazolate framework (ZIF-67) derived cobalt and nitrogen-doped carbon on reduced graphene oxide (Co-N-C/rGO). ZIF-67 cubic crystals were synthesized in situ and deposited onto the graphene oxide (GO) surface through room-temperature reactions. High-temperature calcination resulted in partially collapsed cubic and spherical carbon, while simultaneously reducing GO to rGO. A molecular imprinting resorcinol polymer (MIP) membrane was also in situ applied to the Co-N-C/rGO/glassy carbon electrode (GCE) via electropolymerization. Analyses using cyclic voltammetry, electrochemical impedance, and pulse voltammetry reveal that the modified MIP/Co-N-C/rGO/GCE electrodes show improved electroconductivity and notable electrochemical reactivity towards dopamine. After optimizing detection parameters, the sensor demonstrates a wide linear detection range of 0.01-0.5 and 0.5-100μmol/L, with a limit of detection (LOD) of 3.33nmol/L (S/N = 3). Additionally, the sensor displays strong robustness, including excellent selectivity, significant resistance to interference, and long-term stability. It also shows satisfactory recovery in detecting spiked real samples.

Interfacical polarization dominant rGO aerogel decorated with molybdenum sulfide towards lightweight and high-performance electromagnetic wave absorber

Lightweight reduced graphene oxide aerogel (rGO) has obtained enormous attention as microwave absorber due to anisotropic characteristics in their structure and electromagnetic parameters. However, the controllable preparation of reduced graphene oxide (rGO) aerogels with tailored multidimensional structure with broadened effective absorption bandwidth is a thorny difficulty. In this paper, rGO aerogel decorated with molybdenum sulfide (rGO/MoS2) with three-dimensional (3D) layered porous structure were synthesized by a two-step hydrothermal method. The unique three-dimensional layered porous structure of graphene aerogel not only effectively avoids the stacking of graphene flake layers, but also provides space for the loading of MoS2 nanosheets. The introduction of MoS2 nanosheets compensates for the imbalance of impedance matching caused by graphene due to the excessive conductivity, and the folded MoS2 nanosheets are uniformly loaded on the graphene lamellae, which is conducive to generate multiple reflections and scattering of electromagnetic waves. Besides, the construction of heterogeneous interfaces strengthens the interfacial polarizability of the composites. As a result, excellent electromagnetic wave attenuation properties were obtained for rGO/MoS2, and the effective absorption bandwidth (EAB) reached 6.56 GHz at 2.1 mm. In addition, the radar cross section (RCS) simulation results further demonstrate the dissipation capability of the composite in practical application scenarios. This paper provides a new idea for the design of lightweight EM wave absorbing materials with broad absorption bandwidth.

Nanoparticle-based Biosensors for Detection of Heavy Metal Ions

Heavy metal pollution is one of the most serious environmental problems in the world. Many efforts have been made to develop biosensors for monitoring heavy metals in the environment. Development of nanoparticle-based biosensors is the most effective way to solve this problem. This review presents the latest technology of nanoparticle-based biosensors for environment monitoring to detect heavy metal ions, which are magnetic chitosan biosensor, colorimetric biosensor, and electrochemical biosensor. Magnetic chitosan biosensor acts as a nanoabsorbent, which can easily detect and extract poisonous heavy metal ions such as lead ions and copper ions. There are several methods to prepare the chitosan based on the nanoparticle, which are cross-linking, co-precipitation, multi-cyanoguanidine, and covalent binding method. In colorimetric biosensor, gold and silver nanoparticles are commonly used to detect the lead and mercury ions. In addition, this biosensor is very sensitive, fast and selective to detect metal ions based on the color change of the solution mixture. Meanwhile, electrochemical biosensor is widely used to detect heavy metal ions due to a simple and rapid process, easy, convenient and inexpensive. This biosensor is focused on the surface area, which leads to significant improvement in the performance of devices in terms of sensitivity. The wide surface area can affect the performance of the biosensor due to a limited space for operation of electrode. Therefore, reduced graphene oxide is a suitable material for making the electrochemical biosensor due to a wide surface area, good conductivity and high mechanical strength. In conclusion, these three technologies have their own advantages in making a very useful biosensor in the detection of heavy metal ions.

Graphene Synthesis by Electrochemical Reduction of Graphene Oxide and Its Characterizations

Graphene is one of the nanoscale materials that has attracted many researchers to continue in-depth study on its unique properties where both the graphene oxide (GO) and electrochemical reduced graphene oxide (ERGO) are the derivatives of graphene. GO and ERGO can be further modified chemically for many types of application such as sensor and water filter membrane. However, to restore the electrical property of graphene, GO should be reduced to ERGO. There are several types of reduction methods which are fast to produce good quality and high yield of graphene material. However, those methods use toxic chemicals to reduce GO which can bring negative impact to both human and environment. Therefore, an electrochemical approach can be carried out to solve this issue. This study presents the electrochemical synthesis of GO and electrochemical reduction of ERGO. All characterizations were conducted by using Fourier transform infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).

Self-supported electrochemical sensor based on uniform palladium nanoparticles functionalized porous graphene film for monitoring H2O2 released from living cells.

Graphene film has been considered a promising material for the construction of self-supported electrodes due to its favorable flexibility and high conductivity. However, the film fabricated from pristine graphene or conventional graphene sheet reduced graphene oxide processes limited electrocatalytic performance. Decorating active metal species or incorporating heteroatoms intothegraphene framework have been proved to be effective methods to enhance the electrocatalytic efficiency of graphene film-based self-supported electrodes. Herein, we present a freestanding electrode composed of uniform Pd nanoparticles decorating N,S co-doped porous graphene film (Pd/NSPGF) and explore its practical application in differentiating various human colon cell types by in situ tracking the amount of H2O2 secreted from live cells. Our findings reveal that, on the one hand, the NSPGF has abundant surface and inner pores, which promote active site exposure, and mass diffusion during electrochemical reactions; on the other hand, the substitutional doping ofthe graphene framework with heteroatoms (e.g., N or S) can tailor its electronic and chemical properties, and facilitate the uniform loading of high-density Pd nanoparticles. Moreover, the intrinsic activity of Pd/NSPGF is regulated by the interaction of Pd nanoparticles withtheNSPGF support. Taking the advantages of morphology and composition, the self-supported Pd/NSPGF electrode displays remarkable electrochemical performance with a wide linear range up to 2.0mM, low detection limit of 0.1μM (S/N = 3), high sensitivity of 665 µA cm-2mM-1, and good selectivity. When applied in real-time trackingofthe H2O2 released from normal human colon epithelial cells and human colorectal cancer cells, the Pd/NSPGF-based electrochemical sensing system can distinguish the cell types by testing the number of extracellular H2O2 molecules released per cell, which holds considerable potential for early detection and monitoring of disease-related clinical specimens.

Investigating the bifunctional electrocatalytic activity of nickel oxide/nitrogen-doped reduced graphene oxide nanocomposite for zinc-air battery application

Investigating the bifunctional electrocatalytic activity of nickel oxide/nitrogen-doped reduced graphene oxide nanocomposite for zinc-air battery application

Localized surface plasmon resonance induced nonlinear absorption and optical limiting activity of gold decorated graphene/MoS2 hybrid

The synergistic supremacy of a hybrid nanocomposite made of reduced graphene oxide (rGO), molybdenum disulfide (MoS2) and gold nanoparticles (Au) for Q-switching and optical limiting applications is investigated. Hydrothermally synthesized Au-rGO-MoS2 hybrid with varying concentrations of Au (2.5, 5, 7.5 and 10 wt%) was subjected to interact with Q-switched Nd:YAG nanosecond green laser pulses. The intensity dependent nonlinear absorption studies revealed a switch over in the nonlinear behaviour from saturable absorption (SA) to reverse saturable absorption (RSA) behaviour. SA occurs due to ground state bleaching at comparatively lower laser irradiances serving the need for Q-switching and optical communications. The RSA trait at higher laser irradiance is attributed to sequential two-photon absorption which serves as the platform for optical limiting behaviour prompting laser safety and effective photothermal therapy applications. The strong mid-visible and UV absorption promotes the availability of multiple energy bands for energy transitions of excited state absorption (ESA). Enhanced local fields due to localized surface plasmon resonance effect, structural defects, hierarchical morphology, increased absorption cross-section and plasmon induced energy transfer promotes robust ESA process. These tunable nonlinear optical properties make Au-rGO-MoS2 hybrid promising futuristic candidates for applications in nonlinear photonic devices, ultrafast optical switches and all-optical signal processing systems.

Developing Rapid-Charging Li-S Batteries via "Target Catalysis" of Cations and Anions Modified Electrocatalyst.

The shuttle effect and sluggish sulfur reduction reaction have resulted in significantly low efficiency and poor high current cycling stability in lithium-sulfur batteries, impeding their practical applications. To address these challenges, the introduction of Ni cations into MoS2 grown on reduced graphene oxide (MoS2/rGO) induces the formation of impurity energy levels between the conduction and valence bands of MoS2. Additionally, the introduction of anionic Se expands the interlayer spacing, enhances intrinsic conductivity, and improves ion diffusion rates. Simultaneously introducing anionic and cationic species into the MoS2/rGO causes the center of the d-band to shift upward, reducing the occupancy of electrons in antibonding orbitals. This modification leads to a rearrangement of the electronic structure of Mo, accelerating the redox reactions of lithium polysulfides. It particularly enhances the binding energy and lowers the conversion energy barrier of Li2S4. Consequently, the Li||S coin cell with the Ni-MoSSe/rGO cathode demonstrates an initial capacity of 446 mAh g-1 at 20 C, with a remarkable capacity retention of ≈96.7% after 200 cycles. Moreover, even under high sulfur loading conditions (6.45 mg cm-2) and a low electrolyte/sulfur ratio (5.4 µL mg-2), it maintains a high areal capacity of 6.42 mAh cm-2.

Silver-Doped Reduced Graphene Oxide/PANI-DBSA-PLA Composite 3D-Printed Supercapacitors.

This study presents a novel approach to the development of high-performance supercapacitors through 3D printing technology. We synthesized a composite material consisting of silver-doped reduced graphene oxide (rGO) and dodecylbenzenesulfonic acid (DBSA)-doped polyaniline (PANI), which was further blended with polylactic acid (PLA) for additive manufacturing. The composite was extruded into filaments and printed into circular disc electrodes using fused deposition modeling (FDM). These electrodes were assembled into symmetric supercapacitor devices with a solid-state electrolyte. Electrochemical characterization, including cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests, demonstrated considerable mass-specific capacitance values of 136.2 F/g and 133 F/g at 20 mV/s and 1 A/g, respectively. The devices showed excellent stability, retaining 91% of their initial capacitance after 5000 cycles. The incorporation of silver nanoparticles enhanced the conductivity of rGO, while PANI-DBSA improved electrochemical stability and performance. This study highlights the potential of combining advanced materials with 3D printing to optimize energy storage devices, offering a significant advancement over traditional manufacturing methods.

Surface Transformation Of Ultrahigh-Temperature Ceramics HfB2-SiC-C(graphene) Under The Influence Of High-Speed Disossociated Nitrogen Jets

In order to study the promising potential of HfB2–30 vol % SiC ultrahigh-temperature ceramic materials modified with low amounts of reduced graphene oxide for the creation of aerospace equipment intended for use in N2-based atmospheres, the effect of high-speed dissociated nitrogen flow on it has been investigated. It has been established that under the chosen conditions of exposure during the stepwise increase of the anode power supply of plasma torch and, accordingly, the influencing heat flux, at certain parameters there is a sharp increase in the surface temperature from ~1750 to 2000-2100°C. At the same time, further increase of the heat flux has no obvious and proportional effect on the temperature of the sample surface, which may indicate its high catalyticity with respect to the reactions of surface recombination of atomic nitrogen. It is shown that the surface layers of the material undergo chemical transformation (removal of silicon-containing substances, formation of a new phase based on HfN), which is accompanied by a significant change in the microstructure (formation of dendrite-like structures), which affects the optical and catalytic characteristics of the surface.

A sustainable strategy to improve photocatalytic degradation properties of CuO and CuO-rGO nanocomposite using Eucalyptus leaf extract

In this study, Copper oxide (CuO) nanoparticles were synthesized using a sustainable approach. The process comprised Eucalyptus leaf extract as both a biological capping agent and a reducing agent. The synthesis process used a one-pot hydrothermal technique to efficiently combine CuO nanoparticles with reduced graphene oxide (rGO). Analytical methods were utilized to investigate the prepared nanocomposite's structural, crystalline, morphological, functional, optical, and thermal characteristics. The prepared sample was analyzed using X-ray diffraction, which revealed that CuO nanoparticles have a monoclinic crystal structure, and no impurity peaks were observed. Field emission scanning microscopes displayed the uniform dispersion of spherical CuO nanoparticles with layered and non-agglomerated, resembling a sponge-like structure of rGO. The microstructural analysis also confirmed the dispersion of copper inside reduced graphene oxide (rGO) sheets. The optical properties, including light absorption and bandgap width, were investigated using UV–visible spectroscopy using bandgap energies of 2.5 and 2.8 eV. In addition, the nanocomposite's ability to degrade cationic Rhodamine 6G and anionic Rose Bengal dyes by photocatalysis was evaluated. The degradation of RB and Rh6G dyes was characterized by nanocatalysis using UV–visible spectroscopy and a pseudo-first-order kinetics model. The pseudo-first-order degradation kinetic rate of Rhodamine 6G was determined to be 2.55 x 10−2 min−1, indicating that the nanocomposite effectively initiates this dye's degradation. The results showed that dye degradation was effective even at reduced catalyst concentrations.

A bioinspired porous and electroactive reduced graphene oxide hydrogel based biosensing platform for efficient detection of tumor necrosis factor-α.

Oral cancer is one of the leading cancer types, which is frequently diagnosed at an advanced stage, giving patients a poor prognosis and fewer therapeutic choices. To address this gap, exploiting biosensors utilizing anti-biofouling hydrogels for early-stage oral cancer detection in non-invasive body fluids is gaining utter importance. Herein, we have demonstrated the fabrication of an innovative electrochemical immunosensor for the rapid, label-free, non-invasive, and affordable detection of tumor necrosis factor-α (TNF-α), a biomarker associated with oral cancer progression in artificial saliva samples. The gold screen-printed electrodes (gSPEs) are modified with a green synthesized porous and electroactive reduced graphene oxide (rGO) hydrogel utilizing L-cystine (L-cys) as both in situ reducing and surface functionalization agent, followed by covalent immobilization of anti-TNF-α and blocking of residual sites with bovine serum albumin (BSA) to fabricate the BSA/anti-TNF-α/L-cys_rGO hydrogel/gSPE immunosensing platform. The fabricated platform demonstrates excellent performance, with a low limit of detection of 1.20 pg mL-1, a broad linear range from 1 to 200 pg mL-1, and a high sensitivity of 2.10 μA pg-1 mL cm-2 carried out with differential pulse voltammetry (DPV) technique. Moreover, it exhibits specificity towards TNF-α, even in the presence of potential interferents and other cancer biomarkers. Besides, the biosensor showed good reproducibility and repeatability with a relative standard deviation (%RSD) of 5.11% and 1.85%, respectively. Thus, integrating the L-cys_rGO hydrogel in the immunosensor design offers enhanced performance, paving the way for its application in early-stage oral cancer diagnosis.

Integration of Electrical Properties and Polarization Loss Modulation on Atomic Fe–N-RGO for Boosting Electromagnetic Wave Absorption

HighlightsSingle-atom Fe–N4 sites embedded into graphene were successfully synthesized to exert the dielectric properties of graphene.The absorption mechanisms of metal-nitrogen doping reduced graphene oxide mainly include enhanced dipole polarization, interface polarization, conduction loss and defect-induced polarization.Excellent reflection loss of − 74.05 dB (2.0 mm) and broad effective absorption bandwidth of 7.05 GHz (1.89 mm, with filler loading only 1 wt%) were obtained.

Thermally conductive and electrically insulated DGEBA-epoxy nano-composite fabricated by integrating GO/h-BN and rGO/h-BN hybrid for thermal management applications: a comparative analysis

Abstract Thermal interface materials (TIMs) are prerequisite components of micro- and nano-electronics, as well as advanced semiconductor applications. A bisphenol-A epoxy-based thermal adhesive amalgamated graphene oxide (GO), reduced graphene oxide (rGO), and modified hexagonal boron nitride (h-BN/mh-BN) are fabricated. The advantages of adhesive TIMs compared to other TIMs encompass lower cost, process savings, reduced component weight, and prevention of vibration loosening the high-end electronics. Additionally, some parts are not suitable for soldering, as they may lack “legs” that go through holes in the PCBs, and adhesive TIMs help prevent short circuits. The thermal conductivity (TC) is measured at 1.653 ± 0.057 W/mK when incorporating 44.5 wt% mh-BN hybrid rGO into the epoxy matrix. However, substituting rGO with GO reduced the TC to 0.81 ± 0.0289 W/mK due to the lower phonon transfer of GO compared to rGO. The binding strength, in terms of lap shear, of the utmost TC composite adhesive was within the range of 6.26 ± 0.48 MPa, which is acceptable for effective end applications. The thermal stability of both optimized composites (mh-BN/rGO and mh-BN/GO) has demonstrated better results beyond 280 °C. The highest TC epoxy nanocomposite, termed mh-BN/rGO4/epoxy, also revealed electrical insulation properties.

PTFE-based antistatic coatings by incorporating modified carbon black

A kind of antistatic coatings which were applied to nonconductive surfaces were prepared with Polytetrafluoroethylene (PTFE) as matrix, modified carbon black (CB) as conductive filler. Compared to sodium dodecyl sulfate, poly(vinyl pyrrolidone), the TMN-10 modified CB has better wettability, dispersion, stability and re-disperse. When CBTMN-10content is 5 wt.%, the surface resistivity of coating reach to 106Ω*cm, which denotes the coating performance good antistatic behavior. The antistatic coating of 5 wt.% CBTMN-10content is found to exhibit excellent hydrophobicity and high HV hardness. Meanwhile, the low average friction coefficients and wear rate were achieved in antistatic coating of 5 wt.% CBTMN-10content. Furthermore, compared to MXene, reduced graphene oxide, carbon nanotube, the modified CB as conductive material in PTFE antistatic materials could be an useful way not only excellent properties but also large-scale production as well as a reduction in unit cost in antistatic materials.

Facile One-Pot Synthesis of Fe3O4 Nanoparticles Composited with Reduced Graphene Oxide as Fast-Chargeable Anode Material for Lithium-Ion Batteries.

To address the rapidly growing demand for high performance of lithium-ion batteries (LIBs), the development of high-capacity anode materials should focus on the practical perspective of a facile synthetic process. In this work, iron oxide nanoparticles (Fe3O4 NPs) in situ grown on the surface of reduced graphene oxide (rGO), denoted as Fe3O4 NPs@rGO, were prepared through a facile one-pot synthesis under the wet-colloidal conditions. The synthesized Fe3O4 NPs showed that uniform Fe3O4 NPs, with a size of around 9 nm, were distributed on the rGO surfaces. When applied as an anode material for LIBs, the Fe3O4 NPs@rGO anode revealed a high reversible capacity of 1191 mAh g-1 at 1.0 A g-1 after 200 cycles. It also exhibited excellent rate performance, achieving 608 mAh g-1 at a current density of 5.0 A g-1 over 500 cycles, with improved electronic and ionic conductivities due to the rGO template. This suggested that practically available anode materials can be developed through our one-pot synthesis by in situ growing the Fe3O4 NPs.

Surface acoustic wave platform integrated with ultraviolet activated rGO-SnS2 nanocomposites to achieve ppb-level dimethyl methylphosphonate detection at room-temperature

Dimethyl methylphosphonate (DMMP) is commonly used as an alternative for demonstrating to detect sarin, which is one of the most toxic but odorless chemical nerve agents. Among various types of DMMP sensors, those utilizing surface acoustic wave (SAW) technology provide notable advantages such as wireless/passive monitoring, digital output, and a compact, portable design. However, key challenges for SAW-based DMMP sensors operated at room temperature lies in simultaneous enhancement of sensitivities and reduction of detection limits. In this study, we developed a binary material strategy by combining reduced graphene oxide (rGO) and tin disulfide (SnS2) with (100)-facets orientation as sensing layers of SAW device for DMMP detection utilized at room temperature. Ultraviolet (UV) light was applied to activate the sensitive film and reduce the sensor's response time. The developed SAW DMMP sensor demonstrated a superior sensitivity (−1298.82 Hz/ppm), a low detection limit of 50 ppb, and a hysteresis below 1.5%, along with fast response/recovery time (39.2 s/28.4 s), excellent selectivity, long-term stability and repeatability. The formation of shrub-like rGO-SnS2 heterojunctions with abundant surface defects and large specific surface areas, high-energy (100) crystalline surfaces of SnS2, and photogenerated carriers generated by UV irradiation were pinpointed as the crucial sensing mechanisms. These factors collectively enhanced adsorption and reaction dynamics of DMMP molecules.

A novel electrochemical sensor based on reduced graphene oxide decorated with gold nanoparticles for voltammetric sensing of amlodipine in human urine

A novel electrochemical sensor based on reduced graphene oxide decorated with gold nanoparticles for voltammetric sensing of amlodipine in human urine

Sodium-Ion Traps in a Two-Dimensional Confined Channel for Effective Water and Ion Selective Transport.

Nanoconfined interlayer channels in two-dimensional (2D) laminates are promising for the construction of novel permselective membranes. Controlling the interlayer spacing and modifying the interlayer chemical microenvironment are effective for high-efficiency separation. However, manipulating ion-diffusion energy barriers in confined channels is challenging, and their role in selective water-ion transport is unclear. This study engineered sodium-ion traps (SITs) in confined graphene oxide (GO) interlayer channels by incorporating N-phenylaza-15-crown-5 (NPCE) to regulate the ion-diffusion energy barriers. Partial reduction of GO enhanced membrane stability and enabled precise adjustment of interlayer spacing, while the addition of NPCE further constricted the free space and entrapped sodium ions by increasing their transport energy barriers. The optimized membrane with NPCE-dominated SITs achieved mono/monovalent-ion efficient sieving (K+/Na+ ≈ 10.2, and Li+/Na+ ≈ 6.7) and rejection of Na2SO4 (∼99.0%) and NaCl (∼90.0%), while maintaining stable performance for >1500 h. The findings provide new insights into manipulating transport energy barriers and modifying other 2D material laminates.

Possible protective effect of natural flavanone naringenin-reduced graphene oxide nanosheets on nonalcoholic fatty liver disease.

Utilizing naringenin as a safe, natural compound for reducing graphene oxide and to determine whether Nar-RGO more effectively mitigates the harmful effects of HFFD-induced NAFLD compared to crude naringenin. Using a straightforward experimental setup, we utilize the bioactive flavonoid naringenin (NAR) as the reducing agent to synthesize naringenin-reduced graphene oxide nanosheets (Nar-RGO). Naringenin loading on graphene oxide was validated using electroscopic methods(SEM and TEM) and zeta potential measurements. Utilization of reduced graphene oxide for naringenin encapsulation resulted in a significant improvement in hepatic steatosis, insulin resistance, oxidative stress, and signs of inflammation in HFFD-induced NAFLD compared to crude naringenin. This study demonstrates that Nar-RGO exhibits significantly greater efficacy compared to free naringenin. Therefore, it can be used as a promising medicine in counteractinghigh-fat-fructose diet (HFFD)-induced NAFLD.