Graphene Oxide Composites Research Articles

A nano-imprinted graphene oxide-cellulose composite as a SERS active substrate.

Cellulose is a sustainable material capable of forming optically active nanoarrays on its surface. We created a composite of cellulose acetate (CA) and graphene oxide (GO), by mixing GO (0.1 mg mL-1) into CA. This was then imprinted with nanoscale surface features that form Bragg-like modes in resonance with the excitation laser when a thin layer of silver is vapor deposited onto the surface of the substrate. The addition of GO leads to improved surface-enhanced Raman scattering (SERS) signal strengths, obtaining an average SERS signal increase of 1.4-fold following the inclusion of GO. The combination of photonic and electromagnetic effects with charge transfer-based processes that support the SERS chemical mechanism and the possible presence of electromagnetic hot spots from the roughened surface results in an enhanced SERS signal strength when GO is added. This work shows the potential for nanoimprinted graphene oxide/cellulose acetate composites as flexible sensor platforms to detect target molecules.

Tuning the interlayer spacing of graphene oxide membrane via surfactant intercalation for ultrafast nanofiltration

A facile method has been developed to fabricate lamellar composite graphene oxide (CGO) membranes by incorporating positively charged surfactants – cetyltrimethylammonium bromide (CTAB). The interlayer spacing of GO nanosheets was regulated by the sum of both vertical and horizontal alignment of CTAB on the GO surface via electrostatic interaction. The CTAB intercalated GO membrane exhibited an internal layer spacing of 16.97 Å compared to 8.26 Å for the GO membrane. The obtained CGO lamellar membrane with well-defined nanochannels showed ultrafast pure water flux of ∼1112 L h−1 m−2 bar−1 and an excellent separation efficiency of >99 % towards negatively charged organic dye molecules at a high permeation flux of ∼932 L h−1 m−2 bar−1, which was nearly 2.5-fold enhancement compared with that of the pristine GO membrane (∼400 L h−1 m−2 bar−1). The electrostatic and π–π interaction forces between the CGO membrane and organic dye molecules played a major role in the overall dye separation mechanism. Furthermore, the CGO membrane demonstrated excellent stability with no loss in separation performance (>96 % organic molecules rejection) after exposure to various pH solutions and deionized water (DI) water. The current work provides a straightforward approach for the formation of highly tunable and stable CTAB-intercalated GO membranes for ultrafast molecular separation.

Molecularly imprinted sensors for the determination of anthocyanins in food products

A novel molecularly imprinted electrochemical sensor was developed for the sensitive and selective determination of anthocyanins in athletic food products. The sensor was fabricated by incorporating a conductive composite of graphene oxide and gold nanoparticles as the transducer material, which was modified with a silylation agent to enhance compatibility with the molecularly imprinted polymer. The MIP was synthesized using functional monomers that can interact with anthocyanins through hydrogen bonding and π-π interactions. The MIP sensor exhibited a linear response range from 1 nM to 10 μM for cyanidin-3-O-glucoside, with a detection limit of 0.3 nM. The sensor demonstrated high selectivity towards the target anthocyanin, with selectivity coefficients ranging from 7.2 to 48.6 over various interfering compounds. The MIP sensor was successfully applied to the determination of anthocyanin content in commercial athletic food products, with relative errors ranging from -2.1 % to 1.3 % compared to the reference HPLC method. The recoveries of anthocyanins from spiked food samples ranged from 96.4 % to 102.8 %.

Synthesis and photocatalytic properties of Cerium(IV) oxide graphene oxide composites

Semiconductor photocatalytic technology is a simple, efficient, and low-cost method for environmental pollution remediation. Cerium dioxide (CeO2), as a promising oxidative degradation photocatalyst, can solve the problems of energy shortage and environmental pollution. In this paper, cerium dioxide/graphene oxide composites were successfully synthesized by a one-pot hydrothermal method, achieving a degradation rate of 88.96 % for rose red dye in 150 min, and the introduction of reduced graphene oxide effectively improves the photocatalytic performance of pure cerium oxide.

Integration of a Bismuth-Based Tris-Mononuclear Complex with 2D Functional Materials for Highly Efficient and Durable Aqueous Electrocatalytic Hydrogen Evolution.

The eminence of transitioning from traditional fossil fuel-based energy resources to renewable and sustainable energy sources is most evidently crucial. The potential of hydrogen as an alternative energy source has specifically focuses the electrocatalytic water splitting (EWS) as a promising technique for generating hydrogen. Development of efficient electrocatalysts to facilitate the EWS process while rationalizing the limitations of noble metal catalysts like platinum has become one of the daunting tasks. Consequently, porous functional materials such as metal complexes (MCs) and graphene oxide (GO) can act as potential catalysts for EWS. Therefore, a composite of GO and a mononuclear bismuth metal complex is synthesized through in situ facile synthesis, which is further utilized as an efficient electrocatalyst for the hydrogen evolution reaction (HER). Several potential electrocatalytic MC@GO composite (BMGO-3,5,7) materials were prepared with compositional variation of GO (3, 5, and 7 wt %). The experimental results demonstrate that the BMGO5 composite exhibits excellent HER activity with a low overpotential value of 105 mV at 10 mA cm-2 and a low Tafel slope of 44 mV dec-1 in 1 M KOH solution. Furthermore, a comprehensive investigation on the potentiality of the BMC-GO composite for hydrogen evolution from river water splitting was performed in order to address the issue of freshwater depletion. Inclusion of a mononuclear MC for facile synthesis of functional GO-based efficient electrocatalyst material is very scanty in the literature. This unique approach could assist future research endeavors toward designing efficient electrocatalysts for sustainable renewable energy generation. This is one of the first of its kind, where mononuclear MCs were utilized to develop GO-based functional composite materials for efficient electrocatalysis toward sustainable renewable energy generation.

Application of N/P-rGO composite electrode materials and novel electrolytes in high-performance supercapacitors

Traditional graphene-based electrode materials often can not have excellent gravimetric and volumetric electrochemical properties at the same time. Furthermore, the gel electrolyte widely used at present has the disadvantages of poor water retention, easy solidification, low ionic conductivity, and narrow working temperature range during the working process. In this paper, nanocellulose/N, P co-doped reduced graphene oxide composites (NC-NPrGOs) were synthesized via a simple approach using graphene oxide (GO), ammonium dihydrogen phosphate, and nanocellulose (NC) as raw materials. Meanwhile, a new type of gel electrolyte (SNG) with renewable, wide working temperature range and ultra-high water retention properties was prepared using sodium alginate (SA), NC, GO, and potassium hydroxide as precursors. Benefiting from the unique physical and chemical properties of NC-NPrGOs, the assembled aqueous symmetric supercapacitors assembled by NC-NPrGOs present high gravimetric (303.9 F/g) and volumetric specific capacitance (416.5 F cm−3), large gravimetric (10.5 Wh kg−1) and volumetric energy density (14.6 Wh/L). Due to the multiple interactions of several components in SNG, the flexible solid-state supercapacitors (ASSC) assembled by NC-NPrGO55 and SNG deliver high specific capacitance (240.0 F/g), ultra-long cycling life, excellent bending resistance, a wide range of operating temperatures, and good regenerative performance. In summary, NC-NPrGOs and SNGs are ideal for the investigation of new energy storage devices.

Quick responding humidity sensor based on polyaniline/reduced graphene oxide composite

The relative humidity sensing response of the Polyaniline/ reduced Graphene Oxide (PRGO) composites has been explored in this present research work. For these observations, polyaniline (PANI), synthesised by the chemical oxidative polymerisation process, was physically blended using the different mass ratios of reduced graphene oxide (rGO). By the improved hummers method, graphene oxide (GO) is prepared, adding the minimal quantity of selenium power, and the GO was effectively and facilely reduced to rGO. By adding different weight per cent (wt%) of reduced Graphene oxide (rGO) to the polymer matrix, PRGO composites were prepared. Structural and morphological properties of rGO were confirmed by XRD, RAMAN, FTIR, SEM, EDX, and HR-TEM (elementary mapping) characterisations. XRD, FTIR SEM and EDX proficiencies were employed to characterise the PRGO composites. For the humidity sensing determination, the sensing film of the PANI, rGO, and PRGO composites is groomed by loading the sample on an IDT substrate through a drop casting technique. The PRGO-3 composite has shown an epitome response and recovery of 3 and 4 s, respectively. The PRGO-3 composite has the most minored and less real sensitivity with a lower limit of detection (LOD). Also, the prepared PRGO composites have recorded less hysteresis and good linearity and depicted exact stability over PANI and other PRGO composites. The physical parameters for PRGO composites were also calculated to determine the potentiality of a perfect sensor. The sensing mechanism also hashed out based on establishing chemisorption and physisorption layers.

Phosphorus‑carbon based hybrid electrodes for sodium ion batteries

In this study, commercial phosphorus powders were first subjected to mechanical ball-milling at varying times and reinforced with graphene oxide and multiwall carbon nanotubes to improve their electrochemical performances. All these processes were carried out by ball milling method to provide mechanical alloying of phosphorus. Subsequently, the crystallinity of the samples was analyzed by X-ray diffraction method, while the morphology of the samples was examined by field emission scanning electron microscopy. The main obstacles that inhibit the reversibility and the cyclic stability of red phosphorus are low electronic conductivity and huge volumetric expansion. Reinforcing amorphized phosphorous with multi-walled carbon nanotube and graphene oxide composites has presented similar initial capacity of 2100 mAh g−1. In addition, reversible capacity of multi-walled carbon nanotube and graphene oxide reinforced samples presented 370 mAh g−1 and 507 mAh g−1 after 250 cycles, respectively. Our results have shown that graphene oxide reinforced composites could be an alternative electrode material for sodium ion battery applications.

Efficiency of magnetic zeolitic imidazolate framework-8 (ZIF-8) modified graphene oxide for lead adsorption.

Simple and efficient removal of Pb(II) ion from aqueous solution through adsorption has accelerated the development of many new composites to improve this popular method. In this study, the composites of graphene oxide (GO), zeolitic imidazolate framework-8 (ZIF-8), and magnetic materials were synthesized via coprecipitation method utilizing a different molar ratio between FeCl2 and FeCl3 of 1:0.5, 2:1, 3:1.5, and 4:2. The ZIF-8/GO was prepared via room temperature synthesis method prior to its further modification with magnetic materials for ease of separation. It was observed that the MZIF-8/GO2 of molar ratio 2:1 showed the best performance in adsorbing Pb(II) ion. As confirmed by FESEM image, it appeared to be ZIF-8 particles that have grown all over the GO platform and overlayed with Fe3O4 granular-shaped particles. The MZIF-8/GO2 successfully achieved 99% removal of Pb(II) within 10min. The optimum values obtained for the initial concentration of Pb (II) were 100mg/L, pH of 4 to 6, and adsorbent dosage used was 10mg. The Langmuir isotherm and the pseudo-second-order kinetic model were deemed suitable to evaluate the adsorption of Pb(II) using MZIF-8/GO2. Results showed that MZIF-8GO2 achieved a maximum adsorption capacity of 625mg/g of Pb(II) adsorption. All parent materials demonstrated a good synergistic effects, while exhibiting a significant contribution in providing active sites for Pb(II) adsorption. Therefore, this ternary composite of MZIF-8/GO2 is expected to be a promising adsorbent for Pb(II) adsorption from aqueous solution with an added value of ease of post phase separation using external magnetic field.

Graphene oxide nanocellulose composite as a highly efficient substrate-free room temperature gas sensor

This study introduces the development of novel, flexible gas sensors operating at room temperature (RT), utilizing a graphene oxide (GO) via the modified Hummers' method and bacterial nanocellulose (BNC) composite to enhance gas detection in industrial and environmental settings. The composite materials, denoted as GO@BNC, were synthesized with varying GO concentrations ranging from 2 % to 30 %, aiming to investigate their responsiveness to gases such as carbon dioxide (CO2), oxygen (O2), acetone (Ac), and ethanol (Eth). The prepared nanomaterials were characterized using FT-IR, Raman, TGA, SEM, and AFM techniques. The bandgap of Go ranges from 4.19, 3.47, 3.16, 2.79, and 2.48 eV for 2, 5, 10, 20, and 30 % GO concentrations, respectively. Notably, the sensor containing wt % of 20 % GO concentration exhibited remarkable sensitivity to Ac, achieving a 270 % increase in resistance at a concentration of 250 μL/L. Conversely, the sensor with a wt % of 30 % GO composition showed superior sensitivity to Eth, with a 420 % signal enhancement under similar conditions. Further modification of GO@BNC through mild reduction resulted in the formation of reduced graphene oxide (rGO@BNC) composites intended to assess the functional groups' impact on sensing performance. Our findings underscore the potential of GO@BNC composites as sustainable and efficient materials for fabricating eco-friendly flexible gas sensors and devices for detecting organic compounds.

Zinc oxide doping graphene oxide composites by brush coating for uniformly one-side formation thin films

Zinc oxide doping graphene oxide composites by brush coating for uniformly one-side formation thin films

Using Sandwiched Silicon/Reduced Graphene Oxide Composites with Dual Hybridization for Their Stable Lithium Storage Properties.

Using silicon/reduced graphene oxide (Si/rGO) composites as lithium-ion battery (LIB) anodes can effectively buffer the volumetric expansion and shrinkage of Si. Herein, we designed and prepared Si/rGO-b with a sandwiched structure, formed by a duple combination of ammonia-modified silicon (m-Si) nanoparticles (NP) with graphene oxide (GO). In the first composite process of m-Si and GO, a core-shell structure of primal Si/rGO-b (p-Si/rGO-b) was formed. The amino groups on the m-Si surface can not only hybridize with the GO surface to fix the Si particles, but also form covalent chemical bonds with the remaining carboxyl groups of rGO to enhance the stability of the composite. During the electrochemical reaction, the oxygen on the m-Si surface reacts with lithium ions (Li+) to form Li2O, which is a component of the solid-electrolyte interphase (SEI) and is beneficial to buffering the volume expansion of Si. Then, the p-Si/rGO-b recombines with GO again to finally form a sandwiched structure of Si/rGO-b. Covalent chemical bonds are formed between the rGO layers to tightly fix the p-Si/rGO-b, and the conductive network formed by the reintroduced rGO improves the conductivity of the Si/rGO-b composite. When used as an electrode, the Si/rGO-b composite exhibits excellent cycling performance (operated stably for more than 800 cycles at a high-capacity retention rate of 82.4%) and a superior rate capability (300 mA h/g at 5 A/g). After cycling, tiny cracks formed in some areas of the electrode surface, with an expansion rate of only 27.4%. The duple combination of rGO and the unique sandwiched structure presented here demonstrate great effectiveness in improving the electrochemical performance of alloy-type anodes.

Two-dimensional hydrophilic imprinted resin–graphene oxide composite for selective extraction and rapid determination of gibberellin traces in licorice samples

This study presents novel methodologies and materials for selectively and sensitively determining gibberellin traces in licorice to address food safety concerns. A novel hydrophilic imprinted resin–graphene oxide composite (HMIR–GO) was developed with fast mass transfer, high adsorption capacity, and exceptional aqueous recognition performance for gibberellin. Leveraging the advantages of molecular imprinting, hydrophilic resin synthesis, and rapid mass transfer characteristics of GO, HMIR–GO was employed as an adsorbent, showing resistance to matrix interference. Coupled with HPLC, a rapid and selective method for determining gibberellin was established. Under optimal conditions, the method exhibited a wide linear range (0.02–5.00 μg g−1, r = 0.9999), low detection limits (3.3 ng g−1), and satisfactory recoveries (92.0–98.4%), enabling the accurate and rapid detection of gibberellin in licorice. This study introduces a pioneering strategy for the selective extraction and determination of trace gibberellin levels, offering insights for similar applications in functional foods.

Construction of polyaniline/MXene/graphene oxide ternary nanohybrid for sequestration and reduction of hypertoxic Cr(VI) in water

The anionic heavy metal contaminant chromium (Cr) is highly mobile, oxidizing, and carcinogenic, predisposing it to a range of biological health and environmental issue. Herein, polyaniline/MXene/graphene oxide ternary nanohybrid (PMG) with multiple types of functional groups and high efficiency of electron transfer capacity was synthesized by electrostatic self-assembly of polyaniline (PANI)-assisted MXene and graphene oxide (GO) two-dimensional nanoplates for the adsorption of hazardous Cr(VI). The charge transfer process promoted the polymerization of aniline on the surface of MXene, and the generation of PANI induced MXene and GO to intercalate with each other and ultimately ameliorated the over-negative potential of the MXene and GO composites. The adsorbent PMG exhibited the optimum adsorption effectiveness of 156.2 mg/g for Cr(VI) at pH = 2 and a sample dosage of 1 g/L. Isotherm and kinetic exploration experiments, combined with the findings of zeta potential, XPS, and first-principles calculations, indicated that approximately 89.3% of Cr(VI) was transformed into Cr(III) and anchored by PMG, revealing the adsorption mechanism to be probably a multilayered chemisorption involving redox reactions, electrostatic interactions, and complexation. The anti-interference experiments and cycling tests further confirmed the prominent application potential of PMG. This study provides feasible insights for remediating water contaminated with hexavalent chromium.

An optimized complementary design based on trilayer graphene oxide and clay composites for three stimuli responsive actuator

To promote the practical development of actuators, it is urgent to develop new multi-responsive actuators. Asymmetric bilayer actuators were reported to be dual-responsive, which can be driven by humidity and light. However, it remains a great challenge to develop rational designs for fabricating high-performance multi-responsive actuators. Here, we propose an optimized complementary design for three stimuli responsive actuators that can respond to multiple organic vapors, humidity, and light. The actuator is designed to achieve complementarity through a trilayer construction with graphene oxide (GO) in the middle layer, and with montmorillonite (MMT) and biaxially-oriented polypropylene (BOPP) on both sides, utilizing their hygroscopicity, organic vapor absorption, light absorption and thermal expansion capabilities. The maximum bending curvatures of the actuator under humidity, organic vapor and light stimulation conditions are 6.60 cm-1, 4.12 cm-1 and 2.59 cm-1 respectively, which are better than that of mixed GO-MMT/BOPP bilayer actuators. To reveal the kinetics of actuation, the actuation speed, temperature and mass during the deformation process are studied, which behave in sync with the bending curvature. Finally, a wireless intelligent claw and an organic-vapor leakage alarm are demonstrated based on these actuators. This study will provide an enlightening reference for multi-responsive actuators and promote their practical development.

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Optimization of methyl orange decolorization by bismuth(0)-doped hydroxyapatite/reduced graphene oxide composite using RSM-CCD

In the current study, the catalyst for the decolorization of methyl orange (MO) was developed HAp-rGO by the aqueous precipitation approach. Then, bismuth(0) nanoparticles (Bi NPs), which expect to show high activity, were reduced on the surface of the support material (HAp-rGO). The obtained catalyst was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. The parameters that remarkably affect the decolorization process (such as time, initial dye concentration, NaBH4 amount, and catalyst amount) have been examined by response surface methodology (RSM), an optimization method that has acquired increasing significance in recent years. In the decolorization of MO, the optimum conditions were identified as 2.91 min, Co: 18.85 mg/L, NaBH4 amount: 18.35 mM, and Bi/HAp-rGO dosage: 2.12 mg/mL with MO decolorization efficiency of 99.60%. The decolorization process of MO with Bi/HAp-rGO was examined in detail kinetically and thermodynamically. Additionally, the possible decolorization mechanism was clarified. The present work provides a new insight into the use of the optimization process for both the effective usage of Bi/HAp-rGO and the catalytic reduction of dyes.

A highly sensitive electrochemical sensor for the detection of chloramphenicol based on Ni/Co bimetallic metal-organic frameworks/reduced graphene oxide composites

A highly and simply sensitive electrochemical sensor has been developed for the detection of trace chloramphenicol (CAP) in water based on Ni/Co bimetallic metal–organic frameworks-reduced graphene oxide composites [rGO/NiCo-BTC MOFs (BTC = 1,3,5-benzenetricarboxylicacid)] modified glassy carbon electrode (GCE/rGO/NiCo-BTC MOFs). The bare glassy carbon electrode was initially coated with graphene oxide (GO). Subsequently, the GO was electrochemically reduced to obtain reduced graphene oxide (rGO). NiCo-BTC MOFs was grown on the surface of rGO modified electrode by in-situ electrochemical synthesis method to construct GCE/rGO/NiCo-BTC MOFs. The as-made composites films have been characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Further, different electrochemical techniques were utilized for investigating the electrochemical reduction behaviors of CAP at GCE/rGO/NiCo-BTC MOFs. This composites film modified electrode combines the large surface area and excellent electrical properties of rGO with the good catalytic activity of NiCo-BTC MOFs, resulting in a significant enhancement of the electrochemical signal during the electroreduction of CAP. Under the optimized experimental conditions, the sensor exhibits excellent sensing performance for CAP, with a wider linear dynamic range (0.1 − 100 μM), a lower limit of detection (0.235 μM) (S/N = 3) and a ultra-high sensitivity (33.12 μA·μM−1·cm−2). The tap water spiked with different concentrations of CAP were considered. The recoveries range from 97.79 % to 100.07 %, with relative standard deviations ranging from 3.45 % to 5.40 %. The method has been successfully applied for the determination of CAP in real samples, yielding satisfactory results. With further research and development, electrochemical in-situ synthesis of MOFs composites have the potential to revolutionize the design and performance of electrochemical sensors, holding great promise in the field of electrochemical sensing.

One-step solvent thermal synthesis of 3D networked MOF composites for preparation of anultrasensitive chemosensor for hydroquinone and catechol.

Pharmaceuticals and personal care products (PPCPs) have a significant impact on the environment and human health, due to their sometimestoxic and carcinogenic characteristics. Therefore, an innovative chemosensor was constructed for ultrasensitive determinationof two typical PCCPs (hydroquinone (HQ) and catechol (CC)) in several minutes. The homemade chemosensor (UiO-67@GO/MWCNTs) consisted of MOF(UiO-67), graphene oxide (GO), and multi-walled carbon nanotubes (MWCNTs) composites; it was a networked, structurally sparse, porosity-rich, homogeneous octahedral composite, and had ultra-high electrical conductivity, which provided lots of active adsorption sites, promote charge transfer, and enrich lots of molecules to be measured in a few minutes. The prepared electrochemical sensor showed good long-term stability, applicability, reproducibility, and immunity to interference for the determination of HQ and CC, with a wide linear range of response of 5.0 ~ 940µM for both HQ and CC, and a low limit of detection with satisfactory recoveries. In addition, a new strategy of using MOF composites as the basis for electrochemical determination of organic small molecules was established, and a new platform was constructed for the quantitative determination of organic small molecules in various environmental samples.

Magnetic recyclable visible light-driven Bi2WO6/Fe3O4/RGO for photocatalytic degradation of Microcystin-LR: Mechanism, pathway, and influencing factors

Photocatalysis was an attractive strategy that had potential to tackle the Microcystin-LR (MC-LR) contamination of aquatic ecosystems. Herein, magnetic photocatalyst Fe3O4/Bi2WO6/Reduced graphene oxide composites (Bi2WO6/Fe3O4/RGO) were employed to degrade MC-LR. The removal efficiency and kinetic constant of the optimized Bi2WO6/Fe3O4/RGO (Bi2WO6/Fe3O4-40%/RGO) was 1.8 and 2.3 times stronger than the pure Bi2WO6. The improved activity of Bi2WO6/Fe3O4-40%/RGO was corresponded to the expanded visible light adsorption ability and reduction of photogenerated carrier recombination efficiency through the integration of Bi2WO6 and Fe3O4-40%/RGO. The MC-LR removal efficiency exhibited a positive tendency to the initial density of algae cells, fulvic acid, and the concentration of MC-LR decreased. The existed anions (Cl−, CO3−2, NO3−, H2PO4−) reduced MC-LR removal efficiency of Bi2WO6/Fe3O4-40%/RGO. The Bi2WO6/Fe3O4-40%/RGO could degrade 79.3% of MC-LR at pH = 7 after 180 min reaction process. The trapping experiments and ESR tests confirmed that the h+, ∙OH, and ∙O2− played a significant role in MC-LR degradation. The LC-MS/MS result revealed the intermediates and possible degradation pathways.