Graphene Oxide Solution Research Articles

Graphene oxide/polydopamine interface co-reinforced carbon paper: With comprehensive mechanical properties, electrical conductivity and air permeability

Proton Exchange Membrane Fuel Cell ( PEMFC) are characterised by their cleanliness, efficiency and lack of pollution. Carbon paper, the fundamental material for constructing gas-diffusion layer (GDL), plays a crucial role in electron transmission, supporting the electrode structure, and proton transport. However, the traditional carbon paper for GDL significantly limits the large-scale commercial application of PEMFC due to its low mechanical strength and poor conductivity. Based on this, in this paper, polydopamine is used to modify primary carbon fiber paper, a homogeneous mixed solution of graphene oxide and phenolic resin is used as the impregnating agent, and the effects of different GO concentrations on the properties of carbon paper are investigated. The results show that the graphitization degree and mechanical properties of carbon paper are improved with the increase of GO concentration. When the content of polydopamine is 2 g/L and the concentration of GO is 0.5 wt%, the carbon paper exhibits optimal performance. The air permeability of carbon paper is 12.18 L/min, the resistivity is 13.5 mΩ·cm, and the tensile strength is 19.3 MPa. This study provides a simple method for preparing highly breathable and highly conductive carbon paper, offering a reference for achieving low-cost and high-performance carbon paper production, and facilitating the large-scale commercial production of carbon paper.

Development of Biocompatible and Water-Soluble Reduced Graphene Oxide Using Non-Toxic Reducing Agents for Biomedical Applications

Graphene's appeal in various applications stems from its unique properties like remarkable electrical conductivity, impressive mechanical strength, expansive surface area, minimal thermal expansion, and a high aspect ratio. However, its insolubility in water poses challenges for its use in the biomedical sector. This research focuses on developing a method to produce water-soluble and biocompatible graphene suitable for biomedical uses. The study successfully created a stable solution of graphene oxide (GO) in water using a non-ionic Pluronic copolymer. This GO-tripolymer solution maintained its solubility in phosphate buffered saline (PBS) and displayed similar UV absorption characteristics to standard GO. Given the toxicity concerns with traditional reducing agents like hydrazine, this study opted for safer alternatives. Non-toxic substances such as ascorbic acid, galactose, and bovine serum albumin were employed to reduce GO, resulting in a reduced GO (RGO) -tripolymer solution that also showed excellent solubility in PBS. The final phase of the study involved assessing the cytotoxicity of these RGO-tripolymers. The results indicated that these novel RGO-tripolymers exhibit low levels of cytotoxicity, making them potentially suitable for biomedical applications.Keywords: Graphene Oxide (GO), Biocompatibility, Non-Toxic Reducing Agents, Water Solubility and Biomedical Applications

Experimental insights into the stability of graphene oxide nanosheet and polymer hybrid coupled by ANOVA statistical analysis

The synergistic potential of using graphene oxide (GO) nanosheets and hydrolyzed polyacrylamide (HPAM) as GO enhanced polymer hybrid (GOeP) for enhancing oil recovery (EOR) purposes has drawn attention. However, the hybridization method and stability of GOeP have not been comprehensively studied. To cover this gap, the current study evaluates the stability of GOeP under different conditions, including temperatures such as 60 and 80 °C, high and low salinities, and the presence of Mg2+ ions (6430 and 643 ppm). Hence, GO nanosheets were synthesized and characterized through XRD, Raman, FTIR, and DLS techniques. The performance of five preparation methods was assessed to determine their ability to produce stable hybrids. Zeta potential and sedimentation methods, coupled with the ANOVA statistical technique, were used for measuring and interpreting stability for 21 days. Results revealed that the stability of GOeP in the presence of brine is influenced by hydrolyzation duration, the composition of the water used in polymer hydrolyzation, the form of additives (being powdery or in aqueous solution), and the dispersion quality, including whether the GO solution was prediluted. The results revealed that the positive impact of higher temperatures on the long-term stability of GOeP is approximately seven times less significant than the reduction in stability caused by salinity. Under elevated salinity conditions, a higher Mg2+ concentration led to an 80% decrease in long-term stability, whereas the temperature impact was negligible. These findings highlight the potential of GOeP for EOR applications, offering insights into optimizing stability under challenging reservoir conditions.

Microwave-assisted synthesis of electrode materials for LIBs: MoS2/rGO heterostructures

The incomplete reduction of graphene oxide (GO) yields reduced graphene oxide (rGO), characterized by a zero band gap and intrinsic layer stacking, thus constraining its practical utility across diverse domains. Fortunately, this challenge can be effectively addressed by employing a suitable substrate for the fabrication of MoS2/rGO heterostructures. Nanocomposites of MoS2/reduced graphene oxide (MoS2/rGO-700W and MoS2/rGO-560W) were synthesized using MoS2 and GO solutions as starting materials through microwave-assisted synthesis with microwave power treatments of 700W and 560W, respectively. Structural characterization results reveal that the particle size of MoS2 within the composites is notably smaller compared to that of pure MoS2. The MoS2/rGO-700W composite demonstrates a more homogeneous dispersion of MoS2 and features a well-developed hierarchical porous structure with increased pore volume and specific surface area. The MoS2/rGO-700W composite demonstrates elevated ID/IG ratio, C/O ratio and C = C peak area, suggesting that increased microwave power enhances the removal of oxygen-containing groups from rGO. This process significantly restores the extended conjugated structure of graphene, thereby offering enhanced conductivity at the MoS2 interface. Furthermore, the proposed strategy holds considerable theoretical value and provides significant insights for the development process of novel MoS2-based composite electrode materials.

Four-wave mixing temperature sensor based on graphene oxide-coated microfiber hybrid waveguide

Utilizing a hybrid waveguide comprising microfiber and graphene oxide (GO), this study introduced an innovative temperature sensor based on four-wave mixing (FWM) effect. The methodology involved a tunable continuous wave (TCW) laser and a self-engineered all-fiber mode-locked laser operating at 1560 nm. The microfiber, featuring a minimum diameter of 10 μm, was fabricated through the flame fusion tapering technique, and the microfiber surface was coated with a GO film through the spontaneous evaporation of a GO solution. To improve the stability and robustness of the sensor, a layer of polydimethylsiloxane (PDMS) was applied to the surface as a protective coating. The GO film compensated for dispersion in conjunction with microfiber, enhanced nonlinearity and facilitated low-power FWM phenomena. Furthermore, it increased temperature sensing sensitivity. By measuring the center wavelength shift of the idler and signal light, we achieved a temperature sensing sensitivity of −2.08 nm/℃ from −15 ℃ to 20 ℃ using the CW laser at 1540 nm. This sensor also had a resolution of 0.024 ℃, a response time of 0.12 s and a maximum temporal resolution of 0.08 s. Our study marks the initial investigation of a temperature sensing mechanism employing the FWM phenomenon within this unique hybrid waveguide. It serves as a proof of concept for using a microfiber combined with the two-dimensional material GO film to generate nonlinear FWM for temperature sensing. Continuous optimization of experimental conditions and waveguide dimensions is expected to enhance sensing performance. This opens up new avenues for future research in novel optical sensing technology, particularly in the exploration of high-performance sensors through the integration of nonlinear phenomena with different two-dimensional materials, showcasing substantial research potential.

Flexible Mechanical Sensors Fabricated with Graphene Oxide-Coated Commercial Silk.

Many studies on flexible strain and pressure sensors have been reported due to growing interest in wearable devices for healthcare purposes. Here, we present flexible pressure and strain (motion) sensors prepared with only graphene oxide (GO) and commercial silk fabrics and yarns. The pressure sensors were fabricated by simply dipping the silk fabric into GO solution followed by applying a thermal treatment at 400 °C to obtain reduced GO (rGO). The pressure sensors were made from rGO-coated fabrics, which were stacked in three, five, and seven layers. A super-sensitivity of 2.58 × 103 kPa-1 at low pressure was observed in the seven-layer pressure sensor. The strain sensors were obtained from rGO-coated twisted silk yarns whose gauge factor was 0.307. Although this value is small or comparable to the values for other sensors, it is appropriate for motion sensing. The results of this study show a cost-effective and simple method for the fabrication of pressure and motion sensors with commercial silk and GO.

The Janus Structure of Graphene Oxide and Its Large-Size Conductive Film Strip Pattern.

In this paper, the oxidation-exfoliation process of graphite is studied experimentally by the mixed-solvent method, the oxidation-exfoliation process of graphite is simulated theoretically, and it is found that Graphene Oxide (GO) is a Janus structure with inconsistent oxidation on both surfaces; hydrophilic on one side and hydrophobic on the other side. This layer structure and layer spacing are due to the inconsistent oxidation on both sides which changes with the polarity of different solvent mixtures. We used a two-phase system of benzyl alcohol and water, as well as controlling the polarity of the surface of the substrate, to achieve (using a mixed solution of GO which has a selectivity more inclined to the oil phase when the aqueous phase is present) the preparation of reduced graphene oxide patterns. We also used a complex solution of hydrogen iodide and a sodium-iodide complex solution for secondary reduction to enhance its conductivity to 8653 S/m.

Optimization of heat transfer rate of trihybrid nanofluid Embedded between two horizontal coaxial cylinders by RSM

Heat pipes are heat transfer devices that carry heat from one point to another efficiently. The thermal conductivity and heat transfer performance of the heat pipe can be increased by integrating nanofluids, making them appropriate for applications such as electronics cooling, spacecraft thermal management, and heat recovery systems. The suggested work is being carried out for the approximate solution of tri-hybrid nanofluid (copper (Cu), silver (Ag) and graphene oxide (GO)) flow between two horizontal coaxial cylinders. The inner cylinder is rotating with constant velocity and the outer cylinder is fixed. Moreover, the flow is under the influence of magnetic field. The system of governing partial differential equations is converted into a set of non-linear ordinary differential equations by incorporating the suitable similarity transformation and then solved numerically by employing Runga-Kutta 4th order technique. Response surface methodology (RSM) is also incorporated in order to optimize the heat transfer rate by the various combinations of the physical parameters involved in the study. The study revealed that the temperature of the nanofluid increased by raising the strength of the Reynolds number and melting parameter. From optimization technique RSM it came to know that the heat transfer rate reached its peak value when the strength of the Reynolds number and concentration of the nanoparticle of the fluid is higher than normal.

Gamma radiation assisted green synthesis of hesperidin-reduced graphene oxide nanocomposite targeted JNK/SMAD4/MMP2 signaling pathway

In this study, a novel method for the fabrication of hesperidin/reduced graphene oxide nanocomposite (RGOH) with the assistance of gamma rays is reported. The different RGOHs were obtained by varying hesperidin concentrations (25, 50, 100, and 200 wt.%) in graphene oxide (GO) solution. Hesperidin concentrations (25, 50, 100, and 200 wt.%) in graphene oxide (GO) were varied to produce the various RGOHs. Upon irradiation with 80 kGy from γ-Ray, the successful reduction of GO occurred in the presence of hesperidin. The reduction process was confirmed by different characterization techniques such as FTIR, XRD, HRTEM, and Raman Spectroscopy. A cytotoxicity study using the MTT method was performed to evaluate the cytotoxic-anticancer effects of arbitrary RGOH on Wi38, CaCo2, and HepG2 cell lines. The assessment of RGOH’s anti-inflammatory activity, including the monitoring of IL-1B and IL-6 activities as well as NF-kB gene expression was done. In addition, the anti-invasive and antimetastatic properties of RGOH, ICAM, and VCAM were assessed. Additionally, the expression of the MMP2-9 gene was quantified. The assessment of apoptotic activity was conducted by the detection of gene expressions related to BCl2 and P53. The documentation of the JNK/SMAD4/MMP2 signaling pathway was ultimately accomplished. The findings of our study indicate that RGOH therapy has significant inhibitory effects on the JNK/SMAD4/MMP2 pathway. This suggests that it could be a potential therapeutic option for cancer.

Spatial Graphene Structures with Potential for Hydrogen Storage

Spatial graphene is a 3D structure of a 2D material that preserves its main features. Its production can be originated from the water solution of graphene oxide (GO). The main steps of the method include the crosslinking of flakes of graphene via treatment with hydrazine, followed by the reduction of the pillared graphene oxide (pGO) with hydrogen overpressure at 700 °C, and further decoration with catalytic metal (palladium). Experimental research achieved the formation of reduced pillared graphene oxide (r:pGO), a porous material with a surface area equal to 340 m2/g. The transition from pGO to r:pGO was associated with a 10-fold increase in pore volume and the further reduction of remaining oxides after the action of hydrazine. The open porosity of this material seems ideal for potential applications in the energy industry (for hydrogen storage, in batteries, or in electrochemical and catalytic processes). The hydrogen sorption potential of the spatial graphene-based material decorated with 6 wt.% of palladium reached 0.36 wt.%, over 10 times more than that of pure metal. The potential of this material for industrial use requires further refining of the elaborated procedure, especially concerning the parameters of substrate materials.

Deformed graphene FET biosensor on textured glass coupled with dielectrophoretic trapping for ultrasensitive detection of GFAP

Numerous efforts have been undertaken to mitigate the Debye screening effect of FET biosensors for achieving higher sensitivity. There are few reports that show sub-femtomolar detection of biomolecules by FET mechanisms but they either suffer from significant background noise or lack robust control. In this aspect, deformed/crumpled graphene has been recently deployed by other researchers for various biomolecule detection like DNA, COVID-19 spike proteins and immunity markers like IL-6 at sub-femtomolar levels. However, the chemical vapor deposition (CVD) approach for graphene fabrication suffers from various surface contamination while the transfer process induces structural defects. In this paper, an alternative fabrication methodology has been proposed where glass substrate has been initially texturized by wet chemical etching through the sacrificial layer of synthesized silver nanoparticles, obtained by annealing of thin silver films leading to solid state dewetting. Graphene has been subsequently deposited by thermal reduction technique from graphene oxide solution. The resulting deformed graphene structure exhibits higher sensor response towards glial fibrillary acidic protein (GFAP) detection with respect to flat graphene owing to the combined effect of reduced Debye screening and higher surface area for receptor immobilization. Additionally, another interesting aspect of the reported work lies in the biomolecule capture by dielectrophoretic (DEP) transport on the crests of the convex surfaces of graphene in a coplanar gated topology structure which has resulted in 10 aM and 28 aM detection limits of GFAP in buffer and undiluted plasma respectively, within 15 min of application of analyte. The detection limit in buffer is almost four decades lower than that documented for GFAP using biosensors which is is expected to pave way for advancing graphene FET based sensors towards ultrasensitive point-of-care diagnosis of GFAP, a biomarker for traumatic brain injury.

The absorption effect and mechanism of graphene oxide removal from aqueous solution by basalt stone power

Graphene oxide (GO) is a novel carbon material utilized extensively for diverse industrial applications. When exposed to environmental elements like sunlight and chlorination, GO can undergo a series of physical and chemical transformations, and its presence in water and the environment can endanger ecosystems. Therefore there is a need for methods that can effectively remove GO from water. Accordingly, we delve into the efficacy of basalt stone powder (BSP) as an adsorption medium for purifying aqueous solutions of GO. We examine the impact of various experimental parameters—namely pH, initial solution concentration, adsorbent mass, contact duration, and ambient temperature—on GO adsorption, employing the method of controlled variables. The adsorption efficacy is notably influenced by the pH level. At an acidic pH of 3, an initial GO concentration of 80 mg/L, an adsorbent dosage of 50 mg, and a temperature of 303 K (approximately 30 °C), the adsorption removal efficiency reaches an impressive 99 %, boasting a maximum adsorption capacity of 112 mg/g. Dynamically, the adsorption kinetics align most closely with a pseudo-first-order model, achieving equilibrium after 24 h. Thermodynamic analyses reveal that the Langmuir isotherm model most accurately describes the adsorption behavior, indicating an enhancement in BSP's adsorption capacity for GO as temperature rises. Based on thermodynamic equations, the adsorption of GO onto BSP is deduced to be a spontaneous process. Our findings illustrate BSP's considerable potential in the treatment and removal of GO from water, and therefore it may prove useful in environmental remediation efforts.

Improvement of carbon fiber/phenolic composite properties by low-loading graphene oxide and SiO2 nanoparticles

As an ablative thermal protection material, the mechanical properties and ablative resistance of carbon fiber/phenolic (C-Ph) composite should be improved to meet the high requirements in deep space exploration. Herein, the properties of C-Ph composites were improved by the synergistic effect of low-concentration graphene oxide (GO) solution and low mass fraction of SiO2 nanoparticles. Compared to the unmodified C-Ph composite, the compressive strength of the modified composites was increased by 40.75 % and the linear and mass ablation rates were reduced by 17.78 % and 43.95 %, respectively. The introduction of GO effectively improved the interfacial bonding between the fiber and phenolic resin. Meanwhile, the uniformly dispersed SiO2 nanoparticles resisted the applied loads, thus synergistically enhancing the mechanical properties of the composites. In terms of improving ablation resistance, GO promoted the graphitization of fibers and enhanced the stability of the char layer. Concurrently, SiO2 nanoparticles reacted with the carbon matrix under high temperatures to form ablation-resistant SiC, thus synergistically enhancing the ablative properties of the composite.

Detection of 238Pu at picogram quantities by laser resonance ionization mass spectrometry

Based on the laser resonance ionization mass spectrometry (LRIMS) developed in the laboratory, a preliminary method was established to determine Pu isotope ratios. A three-color-three-photon resonance ionization scheme was confirmed, and the laser wavelengths of each excitation/ionization step were λ1 = 586.654 nm, λ2 = 606.181 nm and λ3 = 642.722 nm. The selective ionization of 238Pu/238U was realized by testing the Pu and U mixed sample, a selectivity ratio of over 107 was obtained. More effective electrothermal atomization of Pu was implemented by loading graphene oxide solution on the Pu sample surface, and the total detection efficiency of ∼40 ng Pu sample was above 3 × 10−4, which was three orders of magnitude higher than the efficiency of the unloaded graphene oxide solution Pu sample. Results showed that the relative standard deviation of 238Pu/239Pu ratio was ∼0.20%, indicating that LRIMS could effectively avoid the isobaric interference of 238U faced by other commercial mass spectrometers such as TIMS and ICP-MS, and could achieve precise measurement of 238Pu/239Pu ratio.

Effects of graphene-oxide and nanosilica on the wear resistance and strength of self-consolidating high-strength cement mortar

ABSTRACT This paper investigates the effects of the nanosilica (NS) and graphene oxide (GO) on the mechanical properties of the self-consolidating high-strength cement mortars (SCHSCM). Ten different mortar mixes, including aqueous solutions of GO and NS, were designed to perform the experimental study. Multiple specimens are prepared for each mortar mix to be tested to determine the mean tensile, flexural and compressive strength as well as wear resistance of the SCHSCM at 28 days of curing. Different contents of GO (0.00%, 0.01%, 0.02% and 0.05% by weight of cement) and NS (0.0%, 1.5% and 3% by weight of cement) are used in the experiments. The hybrid effects of the NS and GO on the mechanical properties of the SCHSCM are also investigated. The obtained results illustrate that the simultaneous use of 0.01% of GO and up to 3% of NS can increase the flexural, tensile and compressive strength of SCHSCM up to 45%, 30% and 26%, respectively, which are higher than those obtained by using NS and GO separately. However, the hybrid use of GO and NS has negative effects on the abrasion depth while the NS additive could improve the abrasion resistance of the SCHSCM.

Development of biodegradable nanofiber filters based on surface-modified cellulose nanofibers with graphene oxide for high removal of airborne particulate matter

Airborne particulate matter is a pressing environmental and public health concern globally. This study aimed to develop sustainable filtration materials from cellulose nanofibers (CNFs) modified with graphene oxide (GO) to capture fine particulates from air effectively. CNFs were extracted from α-cellulose via mechanical grinding and modified with 0.5–1.5 wt% GO solution by ultrasonication to produce CNF-GO nanocomposites. These were freeze-dried into highly porous, lightweight aerogels for air filtration applications. Fourier transform infrared spectroscopy (FT-IR) confirmed GO incorporation through hydroxyl group interactions. Field emission scanning electron microscopy (FE-SEM) revealed a porous 3D network with reduced porosity after GO addition due to pore blocking. X-ray diffraction analysis showed the cellulose I crystal structure was retained after modification. Brunauer-Emmett-Teller (BET) measurements indicated increased density but decreased surface area and pore volume with GO loading. The thermogravimetric analysis demonstrated improved thermal stability with GO incorporation due to oxidative reactions and a barrier effect. The particulate absorption efficiency markedly increased from 86.37 % to 99.98 % for CNFs modified with 1.5 wt% GO due to the high surface area, surface oxygen functionalities, and nanoplatelet morphology of GO. The nanofiber filters with 1.5 wt% GO exhibited a maximum absorption efficiency of 99.98 % and a quality factor of 0.0912 Pa−1. Although GO reduced biodegradability, substantial degradation occurred under soil conditions. Overall, the sustainable, high-efficiency CNF-GO air filters developed in this work demonstrate immense promise for controlling air pollution and protecting human health.

Properties evaluation of concrete made with recycled coarse aggregate modified by graphene oxide

Previous application of graphene oxide (GO) in recycled aggregate concrete (RAC) is the direct replacement of cement or binder to achieve performance improvement. To develop a more efficient recycled aggregate (RA) modification technique and improve the properties of the corresponding RAC, this paper performed GO solution pre-spraying and pre-soaking treatment on RA. The modification efficiency of GO was evaluated by compressive strength, interfacial transition zone (ITZ) properties, and chloride ion permeability of RAC. The results show that the pre-spraying and pre-soaking methods improved the compressive strength of RAC at different ages by 20%–28.6 % and 8.3%–30.8 %, respectively. The GO-modified RAC also exhibited lower electric flux in the chloride ion permeability tests. However, no significant effect was observed on the elastic modulus of RAC. The modified RAC showed lower total porosity and harmful pore content. Meanwhile, the GO-modified ITZ between old and new mortar had denser hydration products. As a result, the elastic modulus and hardness of the ITZ increased by 27.8%–65.8 % and 9.8%–107 %, respectively, while the width of the ITZ decreased by 15.4%–30.8 %. The good filling and nucleation effect of GO were credited with the enhancement mechanism of RA by pre-spraying and pre-soaking methods.

Exploration of the impact of graphene oxide, acetylenic gemini, and CTAT on the photophysical and aggregation properties of dipolar coumarin 153.

Advanced spectroscopic techniques have been utilized to study the interaction between the laser dye coumarin 153 (C153) and graphene oxide (GO) nanoparticles. GO was synthesized using a modified Hummers' method and characterized by UV-vis spectroscopy, Raman laser spectroscopy, FTIR-ATR spectroscopy, FESEM, HR-TEM, and XRD techniques. The GO@C153 composite was formed by mixing two aqueous solutions of GO and C153 due to their strong interaction through stacking and hydrophobic interactions. In this case, GO acts as an effective fluorescence quencher for C153 molecules, which undergo H-type aggregation in the presence of GO. The Stern-Volmer equation and time-dependent fluorescence studies were utilized to analyse the mechanism of fluorescence quenching. According to the findings, both static and dynamic quenching processes are responsible for the reduction in fluorescence intensity. The effect of surfactants (both cetyltrimethylammonium p-toluenesulfonate (CTAT) and synthesized N,N'-dihexadecyl-N,N,N',N'-tetramethyl-N,N'-but-2-ynediyl-di-ammonium chloride (16-4-16)) on the aggregation and photophysical properties of the dye was investigated using surface tensiometry, conductometry, UV-vis absorption spectroscopy, steady-state fluorescence measurements, DLS, and time-dependent fluorescence spectroscopy. Surfactants change the microenvironment of the C153 dye, leading to spectrum shifting and a higher quantum yield, which causes a rapid rise in fluorescence intensity in the micellar medium. It has been noted that in a micellar medium rather than in an aqueous one, the luminous intramolecular charge transfer (ICT) state of C153 stabilises. Lastly, we investigated the photophysical behavior of the GO-C153-micelle ternary system and discovered that, in the presence of a micellar medium, the quenched and blue-shifted (H-type aggregation) fluorescence peak of C153 (in the presence of GO) began to intensify once more. The main goal of this work is to create an effective and fairly cost powerful fluorescence sensor. Additionally, the ternary system (GO-C153-micelle) analytical idea can be employed to identify the onset of micelle formation. In wastewater treatment analysis, the GO-C153-surfactant ternary system concept can also be used to regenerate the adsorbent (in this case, GO) from dye molecules by allowing the dye molecules to exit the adsorbent and enter the micellar medium.

Hydrogen bonding-regulated miscibility of graphene oxide and nonionic water-soluble polymers.

The integration of graphene and nonionic water-soluble polymers has generated useful composites with high performances and rich functionalities. These attractive graphene composites are usually synthesized from the aqueous mixture of graphene oxide (GO) precursor and polymers such as synthetic polyvinyl alcohol and natural cellulose. In this widely known preparation method, the miscibility of GO and nonionic water-soluble polymers seems to be intuitive but has been disputed by some observations of gelation and aggregation. Herein, we have re-examined the miscibility of GO and nonionic water-soluble polymers and confirm their general coaggregation caused by hydrogen bonding interaction. Due to the increasing GO concentration, the property of stable miscibility is converted to aggregation by surface adsorption with transient hydrogen bond crosslinking. We have proposed a preheat mixing strategy to prepare a homogenous solution of GO and nonionic water-soluble polymers in any arbitrary ratio. The re-exploited miscibility allows the fabrication of homogeneous composite papers with renewed high performance trend. The hydrogen bonding-regulated miscibility refreshes the understanding on graphene/water-soluble polymeric composites and provides an ecofriendly interaction control method to modulate the assembly of structures and materials.

High-response room-temperature NO2 gas sensor fabricated with thermally reduced graphene oxide-coated commercial cotton fabric

Electronic textile-based gas sensors with a high response for NO2 gas were fabricated using reduced graphene oxide (rGO)-coated commercial cotton fabric (rGOC). Graphene oxide (GO) was coated on cotton fabric by simply dipping the cotton into a GO solution. To investigate the relationship between the degree of reduction and the sensing response, the GO-coated fabrics were thermally reduced at various temperatures (190, 200, 300, and 400 °C). The change in the amount of oxygen functional groups on the rGOCs was observed by x-ray photoelectron spectroscopy, Raman spectroscopy, and x-ray diffraction patterns. The maximum sensing response of 45.90 % at 10 ppm of NO2 gas at room temperature was exhibited by the rGOC treated at 190 °C, which was the lowest heat-treatment temperature. The high response comes from the greater amount of oxygen functional groups compared to other rGOC samples, and the tubular structure of the cotton.