Artykuły w czasopismach: „Graphene-Solvent Interactions”

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Abahussain, Abdulaziz A. M., S. Z. J. Zaidi, M. H. Nazir, M. Raza, M. H. Nazir i S. Hassan. "A DFT Study of Graphene as a Drug Carrier for Gemcitabine Anticancer Drug". Journal of New Materials for Electrochemical Systems 25, nr 4 (31.12.2022): 234–39. http://dx.doi.org/10.14447/jnmes.v25i4.a02.

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Research is being carried out worldwide for possible treatment of cancer. Graphene has been studied as a drug carrier for various cancer-related drugs [1-2]. In the present work, we apply theoretical models to study the electrons interactions, thermodynamic properties, and solvent interaction of the drug-carrier configuration. The stability of graphene means that it can be a nanocarrier in the biological system. The simulations result shows that graphene provides a stable base, where gemcitabine is a highly dissolvable and reactive drug. The adsorption of gemcitabine on the graphene was physical. The drug carrier configuration formed a highly impactful drug-carrier design.

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Liang, Yanyu, Dongqing Wu, Xinliang Feng i Klaus Müllen. "Dispersion of Graphene Sheets in Organic Solvent Supported by Ionic Interactions". Advanced Materials 21, nr 17 (4.05.2009): 1679–83. http://dx.doi.org/10.1002/adma.200803160.

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Graziano, Antimo, Shaffiq Jaffer i Mohini Sain. "Graphene oxide modification for enhancing high-density polyethylene properties: a comparison between solvent reaction and melt mixing". Journal of Polymer Engineering 39, nr 1 (19.12.2018): 85–93. http://dx.doi.org/10.1515/polyeng-2018-0106.

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Abstract Graphene oxide (GO) was chemically modified in xylene with dodecyl amine and hydrazine monohydrate to obtain reduced functionalized graphene oxide (RFGO). Composites of high-density polyethylene (HDPE) and GO were made via solvent reaction, whereas both melt mixing and solvent reaction were used for HDPE-RFGO composites for comparison purposes. Elemental and thermal analysis showed the success of GO modification in grafting amine functionalities onto its structure and restoring most of the original graphene C=C bonds. A significant increase in mechanical properties, thermal stability, and crystallization behavior was observed for HDPE-RFGO (solvent) compared with HDPE and HDPE-GO, proving that homogeneous dispersion of RFGO in the polymer matrix and strong interactions between them resulted in facilitated stress transfer, delayed thermal degradation, and more efficient nucleating effect in inducing the crystal growth of HDPE. A comparison of HDPE-RFGO properties enhancement between the melt mixing method and the solvent reaction method showed that, apart from mechanical behavior, the RFGO contribution was the same, suggesting that the optimization of the ecofriendlier approach (melt) could eventually lead to its total use for the mass production of high-performance, cost-effective, and more environmentally friendly graphene-based thermoplastic polyolefin nanocomposites suitable for highly demanding industrial applications.

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Berisha, Avni. "Interactions between the Aryldiazonium Cations and Graphene Oxide: A DFT Study". Journal of Chemistry 2019 (26.02.2019): 1–5. http://dx.doi.org/10.1155/2019/5126071.

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Understanding the grafting behavior of the aryldiazonium cations is of fundamental and also of practical importance for the vast number of applications that involve the use of modified graphene oxide (from simple adsorption process to electronic and photovoltaic applications). In this work, the mechanism of the adsorption and grafting of diazonium cations on the graphene oxide surface was investigated by the use of density functional theory. Two types of aryldiazonium cations, one bearing only phenyl ring and the other nitrophenyl, were selected as adsorbates/grafted moiety. By evaluating the adsorption energies at 7 different positions onto the graphene oxide both in the gaseous and solvent phase (using COSMO approach), the most probable adsorption sites were found. Moreover, the most stable adsorption sites were used to calculate and plot NCI (noncovalent interactions). The obtained results are important as they not only give molecular insights regarding the nature of the interaction and its dependence on the adsorption site of the graphene oxide surface but also on the activation energy for such a grafting reaction to take place, providing a mechanistic aspect to understand these grafting reactions.

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Arunachalam, Vaishali, i Sukumaran Vasudevan. "Graphene–Solvent Interactions in Nonaqueous Dispersions: 2D ROESY NMR Measurements and Molecular Dynamics Simulations". Journal of Physical Chemistry C 122, nr 3 (10.01.2018): 1881–88. http://dx.doi.org/10.1021/acs.jpcc.7b11138.

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Czajka, Michael, Robert A. Shanks i Ing Kong. "Preparation of graphene and inclusion in composites with poly(styrene-b-butadiene-b-styrene)". Science and Engineering of Composite Materials 22, nr 1 (1.01.2015): 7–16. http://dx.doi.org/10.1515/secm-2013-0119.

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AbstractThe aim of this work was to prepare and characterize nanocomposites containing graphene from intercalated graphite. The graphene was produced by rapid thermal expansion using expandable graphite oxide or obtained commercially. The polymer used was poly(styrene-b-butadiene-b-styrene) (SBS). The SBS was dissolved in p-xylene and the graphene was ultrasonically suspended in the xylene solution. The morphology, dynamic mechanical, electrical, and thermal properties of composites were characterized. Graphene at 1% (w/w) (hydrogen atmosphere) was found to increase the storage modulus (68%) and loss modulus (147%) of the glassy state of polybutadiene in SBS. The damping factor of SBS was enhanced by 74% corresponding to the polystyrene phase of SBS using Cheap Tubes graphene. The composites were insulators at 1% (w/w). The styrene groups in SBS strongly adsorb onto the graphenes, preventing a percolation network that would enhance electrical permittivity. Graphene enhanced physical crosslinks of the polystyrene phase to increase the modulus at low concentration. Graphene dispersion using ultrasonic shear depended on π-π interactions between the aromatic rings of the solvent, graphene, and polystyrene. This is a simple, fast, cheap, and scalable way of making high-quality graphene and a new way of graphene dispersal in polymers.

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Moni, Grace, Jiji Abraham, Chinchu Kurian, Ayarin Joseph i Soney C. George. "Effect of reduced graphene oxide on the solvent transport characteristics and sorption kinetics of fluoroelastomer nanocomposites". Physical Chemistry Chemical Physics 20, nr 26 (2018): 17909–17. http://dx.doi.org/10.1039/c8cp02411a.

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Molecular transport characteristics of fluoroelastomer nanocomposites in aromatic hydrocarbons exhibited improved chemical resistivity by the incorporation of reduced graphene oxide, due to its better reinforcing efficiency and improved polymer-filler interactions.

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Son, Chang Yun, i Zhen-Gang Wang. "Image-charge effects on ion adsorption near aqueous interfaces". Proceedings of the National Academy of Sciences 118, nr 19 (4.05.2021): e2020615118. http://dx.doi.org/10.1073/pnas.2020615118.

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Electrostatic interactions near surfaces and interfaces are ubiquitous in many fields of science. Continuum electrostatics predicts that ions will be attracted to conducting electrodes but repelled by surfaces with lower dielectric constant than the solvent. However, several recent studies found that certain “chaotropic” ions have similar adsorption behavior at air/water and graphene/water interfaces. Here we systematically study the effect of polarization of the surface, the solvent, and solutes on the adsorption of ions onto the electrode surfaces using molecular dynamics simulation. An efficient method is developed to treat an electrolyte system between two parallel conducting surfaces by exploiting the mirror-expanded symmetry of the exact image-charge solution. With neutral surfaces, the image interactions induced by the solvent dipoles and ions largely cancel each other, resulting in no significant net differences in the ion adsorption profile regardless of the surface polarity. Under an external electric field, the adsorption of ions is strongly affected by the surface polarization, such that the charge separation across the electrolyte and the capacitance of the cell is greatly enhanced with a conducting surface over a low-dielectric-constant surface. While the extent of ion adsorption is highly dependent on the electrolyte model (the polarizability of solvent and solutes, as well as the van der Waals radii), we find the effect of surface polarization on ion adsorption is consistent throughout different electrolyte models.

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Borzehandani, Mostafa Yousefzadeh, Emilia Abdulmalek, Mohd Basyaruddin Abdul Rahman i Muhammad Alif Mohammad Latif. "Elucidating the Aromatic Properties of Covalent Organic Frameworks Surface for Enhanced Polar Solvent Adsorption". Polymers 13, nr 11 (3.06.2021): 1861. http://dx.doi.org/10.3390/polym13111861.

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Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 and covalent triazine-based frameworks (CTF-1), are studied. In addition, a theoretical porous graphene (TPG) was included for comparison purposes. The three solid sheets were investigated for aromaticity and stability using quantum mechanics calculations and their ability for water and ethanol adsorption using molecular dynamics simulations. COF-1 demonstrated the poorest aromatic character due to the highest energy delocalization interaction between B–O bonding orbital of sigma type and unfilled valence-shell nonbonding of boron. CTF-1 was identified as the least kinetically stable and the most chemically reactive. Both COF-1 and CTF-1 showed good surface properties for selective adsorption of water via hydrogen bonding and electrostatic interactions. Among the three sheets, TPG’s surface was mostly affected by aromatic currents and localized π electrons on the phenyl rings which in turn made it the best platform for selective adsorption of ethanol via van der Waals interactions. These results can serve as guidelines for future studies on solvent adsorption for COFs materials.

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Araya-Hermosilla, Esteban, Matteo Minichino, Virgilio Mattoli i Andrea Pucci. "Chemical and Temperature Sensors Based on Functionalized Reduced Graphene Oxide". Chemosensors 8, nr 2 (21.06.2020): 43. http://dx.doi.org/10.3390/chemosensors8020043.

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In this work, we investigated the functionalization of reduced graphene oxide (rGO) with 2-(dodecen-1-yl) succinic anhydride (TPSA) to increase the rGO effective interactions with organic solvents both in liquid and vapor phases. Thermogravimetric analysis, STEM, XPS, FTIR-ATR, and Raman spectroscopy confirmed the effective functionalization of rGO with about the 30 wt% of grafted TPSA without affecting the structural characteristics of graphene but successfully enhancing its dispersibility in the selected solvent except for the apolar hexane. Solid TPSA-rGO dispersions displayed a reproducible semiconducting (activated) electrical transport with decreased resistance when heated from 20 °C to 60 °C and with a negative temperature coefficient of 10−3 K−1, i.e., comparable in absolute value with temperature coefficient in metals. It is worth noting that the same solid dispersions showed electrical resistance variation upon exposure to vapors with a detection limit in the order of 10 ppm and sensitivity α of about 10−4 ppm−1.

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Mohammadsalih, Zaid G., Beverley J. Inkson i Biqiong Chen. "Structure and Properties of Polystyrene-Co-Acrylonitrile/Graphene Oxide Nanocomposites". Journal of Composites Science 7, nr 6 (31.05.2023): 225. http://dx.doi.org/10.3390/jcs7060225.

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Polymer/graphene nanocomposites have attracted significant attention from the research community over the past two decades. In this work, nanocomposites of polystyrene-co-acrylonitrile (SAN) and graphene oxide (GO) were prepared using a solution blending method with tetrahydrofuran as the solvent. The GO loadings used were 0.1, 0.25, 0.5, and 1.0 wt.%. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy were employed to characterize the structure and morphology of SAN/GO nanocomposites. Thermal analysis showed increases in the glass transition (Tg) and peak thermal degradation (Tdpeak) temperatures of SAN by the additions of GO, with Tg increasing by 3.6 °C and Tdpeak by 19 °C for 1.0 wt.% GO loading. Dynamic mechanical analysis revealed that the storage modulus of SAN was also enhanced with the incorporations of GO by up to 62% for 1.0 wt.% loading. These property enhancements may be attributed to a good dispersion of GO in the polymer matrix and their interfacial interactions.

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Zhu, Jing, Binglin Lu, Shanshan Liu, Aifei Xu, Guifang Tang, Zhiyan Chen, Yuling Pan, Gangling Tang, Fei Yang i Yun Zhou. "Magnetic Graphene Dispersive Solid-Phase Extraction for the Determination of Phthalic Acid Esters in Flavoring Essences by Gas Chromatography Tandem Mass Spectrometry". Journal of Chromatographic Science 58, nr 8 (29.07.2020): 770–78. http://dx.doi.org/10.1093/chromsci/bmaa032.

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Abstract In the present study, a sensitive, efficient and repeatable method for the simultaneous extraction and determination of 13 types of phthalic acid esters (PAEs) in flavoring essence samples using magnetic graphene solid-phase extraction coupled with gas chromatography tandem mass spectrometry was developed. Due to the unique structure of magnetic graphene, it has several advantages, such as large surface area and fast separation ability. This unique structure not only provided strong magnetic responsiveness for the separation but also prevented the self-aggregation of graphene. The large delocalized p-electron system of graphene can form strong π-stacking interactions with the benzene ring. Thus, graphene may be also a good candidate adsorbent for the adsorption of benzenoid-form compounds. Several magnetic soild-phase extraction parameters, such as elution solvents, amounts of sorbents, enrichment time and desorption time were optimized. The optimized procedures for this method were performed by ultrasonication using ethyl acetate as elution solvent for 5 min. Under the optimal conditions, the developed method provided spiked recoveries of 75.0–105.3% with relative standard deviations of ~5.6% and limits of detection were 0.011–0.091 mg/kg. Good linear relationships were observed with the coefficient of determination (R2) > 0.993 for all the analytes. Finally, the validated method was successfully applied to the analysis of PAEs in real samples.

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Sohail, Uroosa, Faizan Ullah, Nur Hazimah Binti Zainal Arfan, Malai Haniti Sheikh Abdul Hamid, Tariq Mahmood, Nadeem S. Sheikh i Khurshid Ayub. "Transition Metal Sensing with Nitrogenated Holey Graphene: A First-Principles Investigation". Molecules 28, nr 10 (12.05.2023): 4060. http://dx.doi.org/10.3390/molecules28104060.

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The toxicity of transition metals, including copper(II), manganese(II), iron(II), zinc(II), hexavalent chromium, and cobalt(II), at elevated concentrations presents a significant threat to living organisms. Thus, the development of efficient sensors capable of detecting these metals is of utmost importance. This study explores the utilization of two-dimensional nitrogenated holey graphene (C2N) nanosheet as a sensor for toxic transition metals. The C2N nanosheet’s periodic shape and standard pore size render it well suited for adsorbing transition metals. The interaction energies between transition metals and C2N nanosheets were calculated in both gas and solvent phases and were found to primarily result from physisorption, except for manganese and iron which exhibited chemisorption. To assess the interactions, we employed NCI, SAPT0, and QTAIM analyses, as well as FMO and NBO analysis, to examine the electronic properties of the TM@C2N system. Our results indicated that the adsorption of copper and chromium significantly reduced the HOMO–LUMO energy gap of C2N and significantly increased its electrical conductivity, confirming the high sensitivity of C2N towards copper and chromium. The sensitivity test further confirmed the superior sensitivity and selectivity of C2N towards copper. These findings offer valuable insight into the design and development of sensors for the detection of toxic transition metals.

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Yu, Li, Fei Ma, Liangxiao Zhang i Peiwu Li. "Determination of Aflatoxin B1 and B2 in Vegetable Oils Using Fe3O4/rGO Magnetic Solid Phase Extraction Coupled with High-Performance Liquid Chromatography Fluorescence with Post-Column Photochemical Derivatization". Toxins 11, nr 11 (26.10.2019): 621. http://dx.doi.org/10.3390/toxins11110621.

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In this study, magnetic graphene nanocomposite Fe3O4/rGO was synthesized by facile one-pot solvothermal method. The nanocomposite was successfully used as magnetic solid phase extraction (MSPE) adsorbents for the determination of aflatoxins in edible vegetable oils through the π–π stacking interactions. MSPE parameters including the amount of adsorbents, extraction and desorption time, washing conditions, and the type and volume of desorption solvent were optimized. Under optimal conditions, good linear relationships were achieved. Limits of detection of this method were as low as 0.02 µg/kg and 0.01 µg/kg for aflatoxin B1 and B2, respectively. Finally, the magnetic graphene nanocomposite was successfully applied to aflatoxin analysis in vegetable oils. The results indicated that the recoveries of the B-group aflatoxins ranged from 80.4% to 106.0%, whereas the relative standard deviations (RSDs) were less than 8.1%. Owing to the simplicity, rapidity and efficiency, Fe3O4/rGO magnetic solid phase extraction coupled with high-performance liquid chromatography fluorescence with post-column photochemical derivatization (Fe3O4/rGO MSPE-HPLC-PCD-FLD) is a promising analytical method for routine and accurate determination of aflatoxins in lipid matrices.

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Mahendran, R., D. Sridharan, K. Santhakumar i G. Gnanasekaran. "Green Route Fabrication of Graphene Oxide Reinforced Polymer Composites with Enhanced Mechanical Properties". Journal of Nanoscience 2016 (13.07.2016): 1–8. http://dx.doi.org/10.1155/2016/6410295.

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A facile and “Green” route has been applied to fabricate graphene oxide (GO) reinforced polymer composites utilizing “deionized water” as solvent. The GO was reinforced into water soluble poly(vinyl alcohol) (PVA) and poly-2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) matrix by ultrasonication followed by mechanical stirring. The incorporation and dispersion of the GO in the polymer matrix were analyzed by XRD, FE-SEM, AFM, FT-IR, and TGA. Further, the FE-SEM and AFM images revealed that the surface roughness and agglomeration of the GO in the polymer matrix increased by increasing its concentration. Ionic exchange capacity, proton conductivity, and tensile texture results showed that the reinforcement of GO in the polymer matrix enhances the physicochemical properties of the host polymer. These PVA/PAMPS/GO nanocomposites showed improved mechanical stability compared to the pristine polymer, because of strong interfacial interactions within the components and homogeneous dispersion of the GO sheets in the PVA/PAMPS matrix.

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Mohamad, Sharifah, Shabnam Bakhshaei, Ninie Suhana Abdul Manan, N. A. Parmin i Siti Khalijah Mahmad Rozi. "Free Fatty Acid from Waste Palm Oil Functionalized Magnetic Nanoparticles Immobilized on Surface Graphene Oxide as a New Adsorbent for Simultaneously Detecting Hazardous Polycyclic Aromatic Hydrocarbons and Phthalate Esters in Food Extracts". Journal of Nanoscience and Nanotechnology 21, nr 11 (1.11.2021): 5522–34. http://dx.doi.org/10.1166/jnn.2021.19454.

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A newly synthesized free fatty acids from waste palm oil functionalized magnetic nanoparticles immobilized on the surface of graphene oxide (FFA@MNP-GO) was successfully synthesized and characterized in this research. The combinations of long alkyl chain of free fatty acid with graphene oxide that consists of large delocalized 77-electron systems and abundant of hydrophilic groups with hydroxyl, epoxide and carboxylic groups offer the determination of simultaneous wide range of polarities of organic pollutants in real matrices through hydrogen bonding, hydrophobic and 77-77 interactions. The fabricated adsorbent was successfully applied as a magnetic solid phase extraction (MSPE) adsorbent for the simultaneous separation of selected phthalate esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) in apple and cabbage extracts prior to their high performance liquid chromatography with diode-array detector (HPLC-DAD) determination. Factors affecting the extraction efficiency such as amount of adsorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume were investigated and optimized. The results revealed that under optimal conditions, the detection limit of selected PAEs and PAHs were in the range of 0.56-0.97 ng mL-1 and 0.02–0.93 ng mL-1, respectively. The spiked recoveries of real apple and cabbage extracts for PAEs and PAHs were in the range of 81.5-117.6% with good relative standard deviation (RSD) (n = 5) less than 10% and 86.7-118.2% with acceptable RSDs (n = 5) ranging from 1.5 to 11.0%, respectively. This study reported for the first time the use of MSPE procedure for simultaneous determination of chosen PAHs and PAEs in real samples including apple and cabbage extracts by using new adsorbent, FFA@MNP-GO.

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Li, Shuxuan, Can Li, Baowei Su, Michael Z. Hu, Xueli Gao i Congjie Gao. "Amino-functionalized graphene quantum dots (aGQDs)-embedded thin film nanocomposites for solvent resistant nanofiltration (SRNF) membranes based on covalence interactions". Journal of Membrane Science 588 (październik 2019): 117212. http://dx.doi.org/10.1016/j.memsci.2019.117212.

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Shaik, Mohammed, Manawwer Alam, Syed Adil, Mufsir Kuniyil, Abdulrahman Al-Warthan, Mohammed Siddiqui, Muhammad Tahir, Joselito Labis i Mujeeb Khan. "Solvothermal Preparation and Electrochemical Characterization of Cubic ZrO2 Nanoparticles/Highly Reduced Graphene (HRG) based Nanocomposites". Materials 12, nr 5 (28.02.2019): 711. http://dx.doi.org/10.3390/ma12050711.

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A single-step solvothermal approach to prepare stabilized cubic zirconia (ZrO2) nanoparticles (NPs) and highly reduced graphene oxide (HRG) and ZrO2 nanocomposite (HRG@ZrO2) using benzyl alcohol as a solvent and stabilizing ligand is presented. The as-prepared ZrO2 NPs and the HRG@ZrO2 nanocomposite were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD), which confirmed the formation of ultra-small, cubic phase ZrO2 NPs with particle sizes of ~2 nm in both reactions. Slight variation of reaction conditions, including temperature and amount of benzyl alcohol, significantly affected the size of resulting NPs. The presence of benzyl alcohol as a stabilizing agent on the surface of ZrO2 NPs was confirmed using various techniques such as ultraviolet-visible (UV-vis), Fourier-transform infrared (FT-IR), Raman and XPS spectroscopies and thermogravimetric analysis (TGA). Furthermore, a comparative electrochemical study of both as-prepared ZrO2 NPs and the HRG@ZrO2 nanocomposites is reported. The HRG@ZrO2 nanocomposite confirms electronic interactions between ZrO2 and HRG when compared their electrochemical studies with pure ZrO2 and HRG using cyclic voltammetry (CV).

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Díez-Pascual, Ana M. "Effect of Graphene Oxide on the Properties of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate)". Polymers 13, nr 14 (7.07.2021): 2233. http://dx.doi.org/10.3390/polym13142233.

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The main shortcomings of polyhydroxybutyrate (PHB), which is a biodegradable and biocompatible polymer used for biomedical and food packaging applications, are its low thermal stability, poor impact resistance and lack of antibacterial activity. This issue can be improved by blending with other biodegradable polymers such as polyhydroxyhexanoate to form poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), which is a copolymer with better impact strength and lower melting point. However, PHBHHx shows reduced stiffness than PHB and poorer barrier properties against moisture and gases, which is a drawback for use in the food industry. In this regard, novel biodegradable PHBHHx/graphene oxide (GO) nanocomposites have been prepared via a simple, cheap and environmentally friendly solvent casting method to enhance the mechanical properties and antimicrobial activity. The morphology, mechanical, thermal, barrier and antibacterial properties of the nanocomposites were assessed via several characterization methods to show the enhancement in the biopolymer properties. The stiffness and strength of the biopolymer were enhanced up to 40% and 28%, respectively, related to the strong matrix-nanofiller interfacial adhesion attained via hydrogen bonding interactions. Moreover, the nanocomposites showed superior thermal stability (as far as 40 °C), lower water uptake (up to 70%) and better gas and vapour barrier properties (about 45 and 35% reduction) than neat PHBHHx. They also displayed strong biocide action against Gram positive and Gram negative bacteria. These bio-based nanocomposites with antimicrobial activity offer new perspectives for the replacement of traditional petroleum-based synthetic polymers currently used for food packaging.

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Mersal, Gaber A. M., I. S. Yahia i Hamdy S. El-Sheshtawy. "Lone pair Halogen (X2)…π Interactions Stabilizes Molecular Halogens (X2=I2, Br2, Cl2, and F2) on Reduced Graphene Oxide surface: Structural, Solvent Effect and optical properties". Journal of Molecular Structure 1244 (listopad 2021): 130963. http://dx.doi.org/10.1016/j.molstruc.2021.130963.

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Tsai, Hsin-Yen, Munusamy Sathish Kumar, Balaraman Vedhanarayanan, Hsin-Hui Shen i Tsung-Wu Lin. "Urea-Based Deep Eutectic Solvent with Magnesium/Lithium Dual Ions as an Aqueous Electrolyte for High-Performance Battery-Supercapacitor Hybrid Devices". Batteries 9, nr 2 (18.01.2023): 69. http://dx.doi.org/10.3390/batteries9020069.

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A new deep eutectic solvent (DES) made from urea, magnesium chloride, lithium perchlorate and water has been developed as the electrolyte for battery-supercapacitor hybrid devices. The physicochemical characteristics of DES electrolytes and potential interactions between electrolyte components are well analyzed through electrochemical and spectroscopic techniques. It has been discovered that the properties of DES electrolytes are highly dependent on the component ratio, which allows us to engineer the electrolyte to meet the requirement of the battery application. Perylene tetracarboxylic di-imide and reduced graphene oxide ha ve been combined to produce a composite (PTCDI/rGO) that has been tested as the anode in DES electrolyte. This composite shows that the capacitive contribution is greater than 90% in a low scan rate, resulting in the high rate capability. The PTCDI/rGO electrode exhibits no sign of capacity degradation and its coulombic efficiency is close to 99% after 200 cycles, which suggests excellent reversibility and stability. On the other hand, the electrochemical performance of lithium manganese oxide as the cathode material is studied in DES electrolyte, which exhibits the maximum capacity of 76.5 mAh/g at 0.03 A/g current density. After being successfully examined in terms of electrode kinetics, capacity performance, and rate capability, the anode and cathode materials are combined to construct a two-electrode system with DES electrolyte. At a current density of 0.03 A/g, this system offers 43.5 mAh/g specific capacity and displays 55.5% retention of the maximum capacity at 1 A/g. Furthermore, an energy density of 53 Wh/kg is delivered at a power density of 35 W/kg.

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Manza, Hirasing T., Mangesh S. Dhore i Shankar Amalraj. "2D Covalent Interaction of Aminophenol Functionalized Graphene Oxide". ECS Transactions 107, nr 1 (24.04.2022): 16531–37. http://dx.doi.org/10.1149/10701.16531ecst.

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The versatile applications of graphene oxide and its derivatives have attracted scientists to do keen research in the field of functionalized graphene oxide. Herein we report the synthesis of graphene oxide (GO) functionalized with 2,4-diaminophenol (2,4-DAP). This reaction is refluxing at 60oC for 18 hrs under the solvent of dimethylformamide (DMF). The graphene oxide is synthesized from graphite by modified hummer’s method. The developed product is subjected to X-ray diffraction spectroscopy (XRD) and infrared spectroscopy (IR). The results are revealing that the successful intercalation of amine group and GO to form GO-2,4-DAP product.

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Kim, Ho Shin, Sabrina M. Huang i Yaroslava G. Yingling. "Sequence dependent interaction of single stranded DNA with graphitic flakes: atomistic molecular dynamics simulations". MRS Advances 1, nr 25 (2016): 1883–89. http://dx.doi.org/10.1557/adv.2016.91.

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ABSTRACTIn an attempt to understand the structure and dynamics of ssDNA on graphene based surfaces, we performed all-atom implicit solvent molecular dynamics simulations of ssDNA on graphene and graphene oxide (GO) surfaces. Simulations indicate that adsorption of poly(A), poly(T) and poly (AT) have similar mechanisms of adsorption to free standing graphitic flakes, which are governed by a surface oxygen content. Specifically, higher oxygen content of a surface leads to decrease in persistence length of ssDNA. However, the role of DNA sequence on the physisorption mechanism is minimal.

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Oh, Yuna, Hoi Kil Choi, Hana Jung, Jeong-Un Jin, Young-Kwan Kim, Nam-Ho You, Bon-Cheol Ku, Yonjig Kim i Jaesang Yu. "Analysis of the effect of organic solvent–sheet interfacial interaction on the exfoliation of sulfur-doped reduced graphene oxide sheets in a solvent system using molecular dynamics simulations". Physical Chemistry Chemical Physics 22, nr 36 (2020): 20665–72. http://dx.doi.org/10.1039/d0cp03498c.

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In this study, the effect of interfacial interaction between solvent and sheets on the exfoliation of sulfur-doped reduced graphene oxide (SrGO) sheets was studied, using molecular dynamics simulations.

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de Oliveira, Matheus Mendes, Sven Forsberg, Linnéa Selegård i Danilo Justino Carastan. "The Influence of Sonication Processing Conditions on Electrical and Mechanical Properties of Single and Hybrid Epoxy Nanocomposites Filled with Carbon Nanoparticles". Polymers 13, nr 23 (26.11.2021): 4128. http://dx.doi.org/10.3390/polym13234128.

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Graphene nanoplatelets (GNP) and carbon nanotubes (CNT) are used to enhance electrical and mechanical properties of epoxy-based nanocomposites. Despite the evidence of synergetic effects in the hybrid GNP-CNT-epoxy system, there is still a lack of studies that focus on the influence of different dispersion methods on the final properties of these ternary systems. In the present work, direct and indirect ultrasonication methods were used to prepare single- and hybrid-filled GNP-CNT-epoxy nanocomposites, varying the amplitude and time of sonication in order to investigate their effect on electrical and thermomechanical properties. Impedance spectroscopy was combined with rheology and electron microscopy to show that high-power direct sonication tends to degrade electrical conductivity in GNP-CNT-epoxy nanocomposites due to damage caused in the nanoparticles. CNT-filled samples were mostly benefitted by low-power direct sonication, achieving an electrical conductivity of 1.3 × 10−3 S·m−1 at 0.25 wt.% loading, while indirect sonication was not able to properly disperse the CNTs and led to a conductivity of 1.6 ± 1.3 × 10−5. Conversely, specimens filled with 2.5 wt. % of GNP and processed by indirect sonication displayed an electrical conductivity that is up to 4 orders of magnitude higher than when processed by direct sonication, achieving 5.6 × 10−7 S·m−1. The introduction of GNP flakes improved the dispersion state and conductivity in hybrid specimens processed by indirect sonication, but at the same time impaired these properties for high-power direct sonication. It is argued that this contradictory effect is caused by a selective localization of shorter CNTs onto GNPs due to strong π-π interactions when direct sonication is used. Dynamic mechanical analysis showed that the addition of nanofillers improved epoxy’s storage modulus by up to 84%, but this property is mostly insensitive to the different processing parameters. Decrease in crosslinking degree and presence of residual solvent confirmed by Fourier-transform infrared spectroscopy, however, diminished the glass transition temperature of the nanocomposites by up to 40% when compared to the neat resin due to plasticization effects.

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Kadhim, Ishraq Abd Ulrazzaq. "Biocompatibility of Alginate -Graphene Oxide Film for Tissue Engineering Applications". Key Engineering Materials 900 (20.09.2021): 26–33. http://dx.doi.org/10.4028/www.scientific.net/kem.900.26.

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The present paper indicates promising potential of Sodium Alginate) Alg)/Graphene oxide (Go) films in fields bone tissue engineering (TE). The Sodium Alginate (Alg)/Graphene oxide (Go) films, were fabricated via (solvent casting method). The interaction of Sodium Alginate (Alg) with Graphene oxide (Go) via hydrogen bonding was confirmed by FTIR analysis. The swelling degree of Sodium Alginate (Alg)/Graphene oxid (Go) films was also studied. Furthermore, the biocompatibility of Sodium Alginate (Alg)/Graphene oxide (Go) films disclosed its non-cytotoxic effect on the cell lines (MG-63) in-vitro test, the viability of cell lines on the films, and hence its appropriateness as potent biomaterial for tissue engineering.

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27

Neklyudov, Vadim V., Nail R. Khafizov, Igor A. Sedov i Ayrat M. Dimiev. "New insights into the solubility of graphene oxide in water and alcohols". Physical Chemistry Chemical Physics 19, nr 26 (2017): 17000–17008. http://dx.doi.org/10.1039/c7cp02303k.

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Here we demonstrate that the solubility of GO, and the stability of as-formed solutions depend not just on the solute and solvent cohesion parameters, as commonly believed, but mostly on the chemical interactions at the GO/solvent interface.

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Sahu, Sumit Ranjan, Mayanglambam Manolata Devi, Puspal Mukherjee, Pratik Sen i Krishanu Biswas. "Optical Property Characterization of Novel Graphene-X (X=Ag, Au and Cu) Nanoparticle Hybrids". Journal of Nanomaterials 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/232409.

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The present investigation reports new results on optical properties of graphene-metal nanocomposites. These composites were prepared by a solution-based chemical approach. Graphene has been prepared by thermal reduction of graphene oxide (GO) at 90°C by hydrazine hydrate in an ammoniacal medium. This ammoniacal solution acts as a solvent as well as a basic medium where agglomeration of graphene can be prevented. This graphene solution has further been used for functionalization with Ag, Au, and Cu nanoparticles (NPs). The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to reveal the nature and type of interaction of metal nanoparticles with graphene. The results indicate distinct shift of graphene bands both in Raman and UV-Vis spectroscopies due to the presence of the metal nanoparticles. Raman spectroscopic analysis indicates blue shift of D and G bands in Raman spectra of graphene due to the presence of metal nanoparticles except for the G band of Cu-G, which undergoes red shift, reflecting the charge transfer interaction between graphene sheets and metal nanoparticles. UV-Vis spectroscopic analysis also indicates blue shift of graphene absorption peak in the hybrids. The plasmon peak position undergoes blue shift in Ag-G, whereas red shift is observed in Au-G and Cu-G.

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Lashkari, Sima, Sima A. Lashkari i Rajinder Pal. "Ionic Liquid/Non-Ionic Surfactant Mixtures As Versatile, Non-Volatile Electrolytes: Double-Layer Capacitance and Conductivity". ECS Meeting Abstracts MA2022-01, nr 1 (7.07.2022): 5. http://dx.doi.org/10.1149/ma2022-0115mtgabs.

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Self-assembly of ionic liquids (ILs) on 2D materials such as graphene oxide and MXenes facilitated by non-ionic surfactants is a promising approach being increasingly used for the fabrication of high surface area electrodes resulting in high performance supercapacitors. However, the impact that non-ionic surfactants have on double-layer formation and ionic conductivity has yet to be explored. These surfactants are not ionically conductive, have low dielectric constants and high viscosity which are expected to impact the final performance of the electrode. In this study we analyze the effect of adding two commonly used non-ionic surfactants, P123 and Triton X-100 (TX-100) to 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) on the double-layer capacitance formed at a glassy carbon electrode by means of electrochemical impedance spectroscopy. The results, surprisingly suggest an improvement of 75% and 116% in the double layer capacitance measured at the open circuit voltage for 40% of P123 and TX-100, respectively. We also interpret the changes in the DC potential dependence of the capacitance via the most up-to-date understanding of double-layer charging mechanisms with ionic liquids. Similar to previous literature on solvent-based diluents such as polycarbonate and acetonitrile, which cause a similar effect, the improved capacitance is attributed to the reduced Debye length resulting from an increased effective ionic charge accrued by the IL when surrounded by the low-dielectric constant surfactant. Both electrolyte series show the same reduction in ionic conductivity (from 8.5 mS/cm to 1 mS/cm) with respect to concentration regardless of the higher viscosity measured for the P123 electrolyte series. Pulsed field gradient nuclear magnetic resonance, is used to determine the diffusion coefficient for the IL as a function of surfactant concentration and allow us to calculate the effective Stokes radius which is found to shrink significantly as a function of surfactant concentration. Similar to the improved capacitance, this is caused by a reduction in ion-ion interactions and an increase in the average effective charge on each ion. These effects make the electrolyte less sensitive than expected to the increased viscosity caused by addition of the more viscous surfactant phase. The ability to improve the capacitance with non-volatile, low dielectric constant additives, without significantly sacrificing ionic conductivity, opens up an improved avenue for completely non-volatile, non-flammable electrolyte design.

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Ivaništšev, Vladislav, Trinidad Méndez-Morales, Ruth M. Lynden-Bell, Oscar Cabeza, Luis J. Gallego, Luis M. Varela i Maxim V. Fedorov. "Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid–graphene electrode interfaces". Physical Chemistry Chemical Physics 18, nr 2 (2016): 1302–10. http://dx.doi.org/10.1039/c5cp05973a.

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We study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion–electrode interactions in ionic liquids.

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Charoeythornkhajhornchai, Pollawat, i Anongnat Somwangthanaroj. "Synthesis of Graphene Oxide Grafted with Epoxidized Natural Rubber via Aminosilane Linkage". Materials Science Forum 940 (grudzień 2018): 28–34. http://dx.doi.org/10.4028/www.scientific.net/msf.940.28.

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Graphene oxide was synthesized from graphite by Hummer method and connected with (3-aminopropyl) triethoxysilane to form graphene oxide-aminosilane (GO-Si) linkage. The solution was centrifuged and washed with acetone to remove unreacted aminosilane before grafting with epoxidized natural rubber (ENR). ENR dissolved in toluene solution was mixed with GO-Si particle and dried at room temperature. Then, it was grafted to form graphene oxide grated with ENR via aminosilane linkage (GO-Si-ENR) by heat treatment. GO-Si-ENR was washed in toluene to remove unconnected ENR molecule. The synthesized GO particle in each step was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The possible reaction mechanism was proposed in this research. The aim of this synthesis is to improve natural rubber - graphene interfacial interaction thus the dispersion of GO and GO-Si-ENR particle in natural rubber matrix by solvent mixing process was observed by transmission electron microscopy (TEM).

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Wang, Sijie, Gang Liu i Junwen Pu. "Enhancement of the strength of biocomposite films via graphene oxide modification". BioResources 13, nr 3 (5.07.2018): 6321–31. http://dx.doi.org/10.15376/biores.13.3.6321-6331.

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Chitosan-cellulose film is found in food processing and biotechnology because of its biocompatibility, biodegradability, and antibacterial property. Despite the excellent properties, the presence of intramolecular and intermolecular hydrogen bonds cause cellulose and chitosan to be insoluble in common solvents, resulting in limited mechanical strength. Graphene oxide has heavy oxygen-containing functional groups with excellent mechanical properties, which makes it an ideal filler for reinforcing polymers. In this work, blends of graphene oxide and chitosan-cellulose were successfully produced using 1-ally-3-methylimidazolium chloride ([Amim]Cl) and dimethyl sulfoxide (DMSO) as solvent media. Films were prepared by phase-transfer method and investigated by Fourier transform infrared analysis, scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis, and mechanical tests. The absence of the bands corresponding to C=O stretching in graphene oxide and the -NH bending of amides and amines in chitosan, the absence of the diffraction peak at 2θ =11.3° in graphene oxide (XRD), and the improvement of thermal stability and mechanical property provided evidence for the interaction between graphene oxide and chitosan-cellulose.

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33

Jin, Yezi, Zhijun Xu, Yanan Guo i Xiaoning Yang. "Molecular-Level Recognition of Interaction Mechanism between Graphene Oxides in Solvent Media". Journal of Physical Chemistry C 122, nr 7 (9.02.2018): 4063–72. http://dx.doi.org/10.1021/acs.jpcc.7b12017.

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Nair, Adwaita SR, Subhash Mandal, Debmalya Roy i N. EswaraPrasad. "Fabrication of cellular structures in thermoplastic polyurethane matrix using carbonaceous nanofillers". IOP Conference Series: Materials Science and Engineering 1219, nr 1 (1.01.2022): 012004. http://dx.doi.org/10.1088/1757-899x/1219/1/012004.

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Abstract In the present study, we have synthesized, graphene oxide (GO) by using modified Hummer’s method and reduced graphene oxide(rGO) by using hydrazine hydrate as reducing agent. Since GO and rGO have high surface area and modification of surface is easier, they produce drastic changes in the matrix properties at a very low loading volume. Oxygen functionalities further allow increased interaction with polar polymer composites. Modified hummers method is the most commonly and widely used method of chemical reduction to synthesis graphene oxide as it is rapid and safe. Unlike other method, it is less hazardous and requires less reaction time. Sulfuric acid was used to disperse graphite and NaNO3 and KMNO4 as oxidizing agent. The use of KMNO4 instead of KClO3 reduced the chances of ClO2 explosion and also accelerated the reaction. Characterization of graphene oxide and reduced graphene oxide was done using XRD, SEM, FTIR, Raman spectroscopy and TGA. The synthesized GO and rGO were used as nanofillers for the synthesis of polyurethane nanocomposite. Thermoplastic polyurethane is biodegradable and thus polyurethane nanocomposites have wide application. PU nanocomposites were prepared using thermo-chemical solvent mixing method and their microstructures were investigated using various characterization techniques.

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35

Cui, Liting, Haining Wang, Sian Chen, Yiwen Zhang, Zhaoqian Lv, Jin Zhang, Yan Xiang i Shanfu Lu. "The Interaction Energy between Solvent Molecules and Graphene as an Effective Descriptor for Graphene Dispersion in Solvents". Journal of Physical Chemistry C 125, nr 9 (19.02.2021): 5167–71. http://dx.doi.org/10.1021/acs.jpcc.0c10132.

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Rai, K. B., R. P. Yadav, P. M. Shrestha, S. P. Gupta, R. Neupane i R. R. Ghimire. "Fabrication of Gas Sensor Based on Graphene for the Adsorption of Gases Produced from Waste Material in Kitchen and its Surrounding". Journal of Nepal Physical Society 8, nr 3 (30.12.2022): 26–31. http://dx.doi.org/10.3126/jnphyssoc.v8i3.50719.

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Graphene attracted to the researcher with huge attention due to their unique physicochemical properties including high specific surface area and high-speed electron mobility at room temperature. The graphene with several layers was synthesized through liquid phase exfoliation method using high shear force of the magnetic stirrer. This process was performed about 6 hour on the graphite powder and dimethyl-formamide solvent of 0.25 M, 0.5 M and 1 M concentration solution following the microwave treatment for 30 second and sonication for 2 hour at room temperature. The drop-casted exfoliated graphene into glass substrate had G peak and 2D peak. The graphene from 1M concentration had the better quality as compared to the graphene obtained from 0.25M and 0.5M concentration solution. The fabricated gas sensor device with two contact electrodes using exfoliated graphene as a channel material produced the different current (I)–voltage (V) characteristics. The current vs. voltage of bare graphene film without filling of waste harmful gases had the current shifted from 0 mA to 0.0652 mA when the maximum voltage was applied. The current increased nearly from 0.0652 mA to 0.2391 mA after harmful waste gases adjustment at maximum applied voltage. The current through few layers graphene channel after harmful gases filled was found 3.6 times higher than that of the current through the graphene channel without harmful waste gases. This result was due to the adsorption/absorption and interaction of more quantity of harmful waste gases by the exfoliated graphene. So, the device showing some current variation informed that the graphene gas sensor was sensitive to waste gases produced from home kitchen and its surrounding.

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Shtepliuk, Ivan, Maria Santangelo, Mikhail Vagin, Ivan Ivanov, Volodymyr Khranovskyy, Tihomir Iakimov, Jens Eriksson i Rositsa Yakimova. "Understanding Graphene Response to Neutral and Charged Lead Species: Theory and Experiment". Materials 11, nr 10 (22.10.2018): 2059. http://dx.doi.org/10.3390/ma11102059.

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Deep understanding of binding of toxic Lead (Pb) species on the surface of two-dimensional materials is a required prerequisite for the development of next-generation sensors that can provide fast and real-time detection of critically low concentrations. Here we report atomistic insights into the Lead behavior on epitaxial graphene (Gr) on silicon carbide substrates by thorough complementary study of voltammetry, electrical characterization, Raman spectroscopy, and Density Functional Theory (DFT). It is verified that the epitaxial graphene exhibits quasi-reversible anode reactions in aqueous solutions, providing a well-defined redox peak for Pb species and good linearity over a concentration range from 1 nM to 1 µM. The conductometric approach offers another way to investigate Lead adsorption, which is based on the formations of stable charge-transfer complexes affecting the p-type conductivity of epitaxial graphene. Our results suggest the adsorption ability of the epitaxial graphene towards divalent Lead ions is concentration-dependent and tends to saturate at higher concentrations. To elucidate the mechanisms responsible for Pb adsorption, we performed DFT calculations and estimated the solvent-mediated interaction between Lead species in different oxidative forms and graphene. Our results provide central information regarding the energetics and structure of Pb-graphene interacting complexes that underlay the adsorption mechanisms of neutral and divalent Lead species. Such a holistic understanding favors design and synthesis of new sensitive materials for water quality monitoring.

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38

Elazab, Hany A., i Tamer T. El-Idreesy. "Polyvinylpyrrolidone - Reduced Graphene Oxide - Pd Nanoparticles as an Efficient Nanocomposite for Catalysis Applications in Cross-Coupling Reactions". Bulletin of Chemical Reaction Engineering & Catalysis 14, nr 3 (1.12.2019): 490. http://dx.doi.org/10.9767/bcrec.14.3.3461.490-501.

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This paper reported a scientific approach adopting microwave-assisted synthesis as a synthetic route for preparing highly active palladium nanoparticles stabilized by polyvinylpyrrolidone (Pd/PVP) and supported on reduced Graphene oxide (rGO) as a highly active catalyst used for Suzuki, Heck, and Sonogashira cross coupling reactions with remarkable turnover number (6500) and turnover frequency of 78000 h-1. Pd/PVP nanoparticles supported on reduced Graphene oxide nanosheets (Pd-PVP/rGO) showed an outstanding performance through high catalytic activity towards cross coupling reactions. A simple, reproducible, and reliable method was used to prepare this efficient catalyst using microwave irradiation synthetic conditions. The synthesis approach requires simultaneous reduction of palladium and in the presence of Gaphene oxide (GO) nanosheets using ethylene glycol as a solvent and also as a strong reducing agent. The highly active and recyclable catalyst has so many advantages including the use of mild reaction conditions, short reaction times in an environmentally benign solvent system. Moreover, the prepared catalyst could be recycled for up to five times with nearly the same high catalytic activity. Furthermore, the high catalytic activity and recyclability of the prepared catalyst are due to the strong catalyst-support interaction. The defect sites in the reduced Graphene oxide (rGO) act as nucleation centers that enable anchoring of both Pd/PVP nanoparticles and hence, minimize the possibility of agglomeration which leads to a severe decrease in the catalytic activity. Copyright © 2019 BCREC Group. All rights reserved

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Purwandari, Vivi, Saharman Gea, Basuki Wirjosentono, Agus Haryono, I. Putu Mahendra i Yasir Arafat Hutapea. "Electrical and Thermal Conductivity of Cyclic Natural Rubber/Graphene Nanocomposite Prepared by Solution Mixing Technique". Indonesian Journal of Chemistry 20, nr 4 (10.06.2020): 801. http://dx.doi.org/10.22146/ijc.44791.

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Thermal and electrical conductivity studies of Cyclic Natural Rubber nanocomposite with graphene 1 and 2 phr (G1 and G2) and modified 1 and 2 graphenes (mG1 and mG2) have been carried out. Graphene was activated with cetrimonium bromide (CTAB), was isolated from Sawahlunto coal (Bb) by the Hummer modification method. The nanocomposite was fabricated through the mixing solution method using Xylena as a solvent. The characterizations of nanocomposites which were performed by Fourier Transform Infrared (FT-IR) and X-Ray Diffraction (XRD) reveals an interaction between graphene, CTAB and the CNR matrix. Furthermore, Scanning Electron Magnetic (SEM) and Transmission Electron Microscopy (TEM) indicate the particle size to be smaller and particle distribution is more in accordance with CTAB. Thermal analysis of nanocomposites using Differential Scanning Calorimeter (DSC) showed an increase in thermal conductivity from 3.0084 W/mK to 3.5569 W/mK. Analysis of electrical conductivity using the Two-Point Probe shows 2 phr mG (mG2) capable of increasing electrical conductivity from 0.1170 × 10–4 S/cm to 0.2994 × 10-4 S/cm.

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Wang, Jian, Ryuki Suzuki, Kentaro Ogata, Takuto Nakamura, Aixue Dong i Wei Weng. "Near-Linear Responsive and Wide-Range Pressure and Stretch Sensor Based on Hierarchical Graphene-Based Structures via Solvent-Free Preparation". Polymers 12, nr 8 (13.08.2020): 1814. http://dx.doi.org/10.3390/polym12081814.

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Flexible and wearable electronics have huge potential applications in human motion detection, human–computer interaction, and context identification, which have promoted the rapid development of flexible sensors. So far the sensor manufacturing techniques are complex and require a large number of organic solvents, which are harmful not only to human health but also to the environment. Here, we propose a facile solvent-free preparation toward a flexible pressure and stretch sensor based on a hierarchical layer of graphene nanoplates. The resulting sensor exhibits many merits, including near-linear response, low strain detection limits to 0.1%, large strain gauge factor up to 36.2, and excellent cyclic stability withstanding more than 1000 cycles. Besides, the sensor has an extraordinary pressure range as large as 700 kPa. Compared to most of the reported graphene-based sensors, this work uses a completely environmental-friendly method that does not contain any organic solvents. Moreover, the sensor can practically realize the delicate detection of human body activity, speech recognition, and handwriting recognition, demonstrating a huge potential for wearable sensors.

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Zhou, Wei, Qiao Liu, Nong Xu, Qing Wang, Long Fan i Qiang Dong. "In Situ Incorporation of TiO2@Graphene Oxide (GO) Nanosheets in Polyacrylonitrile (PAN)-Based Membranes Matrix for Ultrafast Protein Separation". Membranes 13, nr 4 (26.03.2023): 377. http://dx.doi.org/10.3390/membranes13040377.

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Organic polymeric ultrafiltration (UF) membranes have been widely used in protein separation due to their advantages of high flux and simple manufacturing process. However, due to the hydrophobic nature of the polymer, pure polymeric UF membranes need to be modified or hybrid to increase their flux and anti-fouling performance. In this work, tetrabutyl titanate (TBT) and graphene oxide (GO) were simultaneously added to the polyacrylonitrile (PAN) casting solution to prepare a TiO2@GO/PAN hybrid ultrafiltration membrane using a non-solvent induced phase separation (NIPS). During the phase separation process, TBT underwent a sol–gel reaction to generate hydrophilic TiO2 nanoparticles in situ. Some of the generated TiO2 nanoparticles reacted with the GO through a chelation interaction to form TiO2@GO nanocomposites. The resulting TiO2@GO nanocomposites had higher hydrophilicity than the GO. They could selectively segregate towards the membrane surface and pore walls through the solvent and non-solvent exchange during the NIPS, significantly improving the membrane’s hydrophilicity. The remaining TiO2 nanoparticles were segregated from the membrane matrix to increase the membrane’s porosity. Furthermore, the interaction between the GO and TiO2 also restricted the excessive segregation of the TiO2 nanoparticles and reduced their losing. The resulting TiO2@GO/PAN membrane had a water flux of 1487.6 L·m−2·h−1 and a bovine serum albumin (BSA) rejection rate of 99.5%, which were much higher than those of the currently available UF membranes. It also exhibited excellent anti-protein fouling performance. Therefore, the prepared TiO2@GO/PAN membrane has important practical applications in the field of protein separation.

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Hadano, Fabio Seiti, Anderson Emanuel Ximim Gavim, Josiani Cristina Stefanelo, Sara Luiza Gusso, Andreia Gerniski Macedo, Paula Cristina Rodrigues, Abd Rashid bin Mohd Yusoff, Fabio Kurt Schneider, Jeferson Ferreira de Deus i Wilson José da Silva. "NH3 Sensor Based on rGO-PANI Composite with Improved Sensitivity". Sensors 21, nr 15 (21.07.2021): 4947. http://dx.doi.org/10.3390/s21154947.

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This work reports on a reduced graphene oxide and poly(aniline) composite (rGO-PANI), with rGO clusters inserted between PANI chains. These clusters were formed due the plasticizing effect of N-methyl-2-pyrrolidone (NMP) solvent, which was added during the synthesis. Further, this composite was processed as thin film onto an interdigitated electrode array and used as the sensitive layer for ammonia gas, presenting sensitivity of 250% at 100 ppm, a response time of 97 s, and a lowest detection limit of 5 ppm. The PANI deprotonation process, upon exposure to NH3, rGO, also contributed by improving the sensitivity due its higher surface area and the presence of carboxylic acids. This allowed for the interaction between the hydrogen of NH3 (nucleophilic character) and the -COOH groups (electrophilic character) from the rGO surface, thereby introducing a promising sensing composite for amine-based gases.

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Colburn, Andrew, Ronald J. Vogler, Aum Patel, Mariah Bezold, John Craven, Chunqing Liu i Dibakar Bhattacharyya. "Composite Membranes Derived from Cellulose and Lignin Sulfonate for Selective Separations and Antifouling Aspects". Nanomaterials 9, nr 6 (7.06.2019): 867. http://dx.doi.org/10.3390/nano9060867.

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Cellulose-based membrane materials allow for separations in both aqueous solutions and organic solvents. The addition of nanocomposites into cellulose structure is facilitated through steric interaction and strong hydrogen bonding with the hydroxy groups present within cellulose. An ionic liquid, 1-ethyl-3-methylimidazolium acetate, was used as a solvent for microcrystalline cellulose to incorporate graphene oxide quantum dots into cellulose membranes. In this work, other composite materials such as, iron oxide nanoparticles, polyacrylic acid, and lignin sulfonate have all been uniformly incorporated into cellulose membranes utilizing ionic liquid cosolvents. Integration of iron into cellulose membranes resulted in high selectivity (>99%) of neutral red and methylene blue model dyes separation over salts with a high permeability of 17 LMH/bar. With non-aqueous (alcohol) solvent, iron–cellulose composite membranes become less selective and more permeable, suggesting the interaction of iron ions cellulose OH groups plays a major role in pore structure. Polyacrylic acid was integrated into cellulose membranes to add pH responsive behavior and capacity for metal ion capture. Calcium capture of 55 mg Ca2+/g membrane was observed for PAA-cellulose membranes. Lignin sulfonate was also incorporated into cellulose membranes to add strong negative charge and a steric barrier to enhance antifouling behavior. Lignin sulfonate was also functionalized on the commercial DOW NF270 nanofiltration membranes via esterification of hydroxy groups with carboxyl group present on the membrane surface. Antifouling behavior was observed for both lignin-cellulose composite and commercial membranes functionalized with lignin. Up to 90% recovery of water flux after repeated cycles of fouling was observed for both types of lignin functionalized membranes while flux recovery of up to 60% was observed for unmodified membranes.

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Maya, M. G., Jiji Abraham, Soney C. George i Sabu Thomas. "Exploring the filler–polymer interaction and solvent transport behavior of nanocomposites derived from reduced graphene oxide and polychloroprene rubber". Journal of Applied Polymer Science 136, nr 44 (24.06.2019): 48168. http://dx.doi.org/10.1002/app.48168.

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Rana, Malay Kumar, i Amalendu Chandra. "Solvation of narrow pores of graphene-like plates in simple dipolar liquids: Wetting and dewetting behavior and solvent dynamics for varying pore width and solute–solvent interaction". Chemical Physics 457 (sierpień 2015): 78–86. http://dx.doi.org/10.1016/j.chemphys.2015.05.009.

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Zhou, Fengyi, Xuedan Song, Ce Hao i Jieshan Qiu. "Insight into the Inhibition of Shuttle by Metal-Modified Covalent Triazine Frameworks and Graphene Composites with the Solvent Interaction in Lithium Sulfur Batteries". ACS Applied Energy Materials 5, nr 1 (4.01.2022): 825–31. http://dx.doi.org/10.1021/acsaem.1c03272.

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Fredi, Giulia, Mahdi Karimi Jafari, Andrea Dorigato, Dimitrios N. Bikiaris i Alessandro Pegoretti. "Improving the Thermomechanical Properties of Poly(lactic acid) via Reduced Graphene Oxide and Bioderived Poly(decamethylene 2,5-furandicarboxylate)". Materials 15, nr 4 (10.02.2022): 1316. http://dx.doi.org/10.3390/ma15041316.

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Polylactide (PLA) is the most widely used biopolymer, but its poor ductility and scarce gas barrier properties limit its applications in the packaging field. In this work, for the first time, the properties of PLA solvent-cast films are improved by the addition of a second biopolymer, i.e., poly(decamethylene 2,5-furandicarboxylate) (PDeF), added in a weight fraction of 10 wt%, and a carbon-based nanofiller, i.e., reduced graphene oxide (rGO), added in concentrations of 0.25–2 phr. PLA and PDeF are immiscible, as evidenced by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy, with PDeF spheroidal domains showing poor adhesion to PLA. The addition of 0.25 phr of rGO, which preferentially segregates in the PDeF domains, makes them smaller and considerably rougher and improves the interfacial interaction. Differential scanning calorimetry (DSC) confirms the immiscibility of the two polymer phases and highlights that rGO enhances the crystallinity of both polymer phases (especially of PDeF). Thermogravimetric analysis (TGA) highlights the positive impact of rGO and PDeF on the thermal degradation resistance of PLA. Quasi-static tensile tests evidence that adding 10 wt% of PDeF and a small fraction of rGO (0.25 phr) to PLA considerably enhances the strain at break, which raises from 5.3% of neat PLA to 10.0% by adding 10 wt% of PDeF, up to 75.8% by adding also 0.25 phr of rGO, thereby highlighting the compatibilizing role of rGO on this blend. On the other hand, a further increase in rGO concentration decreases the strain at break due to agglomeration but enhances the mechanical stiffness and strength up to an rGO concentration of 1 phr. Overall, these results highlight the positive and synergistic contribution of PDeF and rGO in enhancing the thermomechanical properties of PLA, and the resulting nanocomposites are promising for packaging applications.

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Gun’ko, V. M., Yu I. Sementsov, L. S. Andriyko, Yu M. Nychyporuk, O. I. Oranska, O. K. Matkovsky, Yu V. Grebel'na, B. Charmas, J. Skubiszewska–Zięba i M. T. Kartel. "2D–nanostructured carbons: effects of oxidation and packing disordering". Himia, Fizika ta Tehnologia Poverhni 14, nr 3 (30.09.2023): 275–99. http://dx.doi.org/10.15407/hftp14.03.275.

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Various 2D carbons demonstrate significant effects of surface oxidation, heating, suspending–drying, cryogelation, swelling, and adsorption of polar and nonpolar compounds on the morphological, structural, and textural characteristics. Heating at 120–150 °C could result in collapse of pores not only between carbon sheets in stacks but also between neighboring stacks; therefore, the specific surface area (SSA) decreases by a factor of 30–100 for preheated graphene oxides (GO). According to the TEM and XRD data, the GO structure is rather amorphous, since only small X-ray coherent scattering regions demonstrate a certain order giving broad XRD (001) and (002) lines. In the Raman spectra, the D line (disordered defect structures with sp3 hybridized C atoms) intensity for GO is similar to that of the G line (ordered structures with sp2 hybridized C atoms). The graphite oxide (GtO) structure, which is closer to that of graphite than that of GO, is characterized by intensive G and low D lines, and the main XRD peak at 26.4° (characteristic for graphite) is broadened similar to the XRD peak of GO at 10°. Despite the GO stacks have a tendency to collapse upon heating, the collapsed stacks can be swollen not only in water (strongly) but also in liquid nitrogen (relatively weakly). Therefore, the use of GO in aqueous media can provide great SSA values in contact with the solvent and solute molecules. This could provide high efficiency of the GO use for purification of wastewater, separation of solutes, etc. MLGO produced from natural flake graphite as a precursor (flakes < 0.2 mm in size) using a modified method of ionic hydration and freeze–drying is characterized by typical light brown color, low bulk density, flexible sheet stacks easily collapsed, but its interaction with water results in strong swelling. Interaction between the carbon sheets in preheated MLGO is strong and nonpolar molecules, such as benzene, n–decane, poorly penetrate between the sheets, i.e., intercalation adsorption is small. However, water molecules can effectively penetrate (this is rather intercalation adsorption resulting in swelling) between the sheets, but the swelling effect of water adsorbed from the gas phase could be weaker than that in the aqueous suspensions. Thus, the proposed synthesis method of MLGO using natural graphite is effective and appropriate for preparation of the materials for various practical applications.

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Chen, Zhongyan, Boqun Zhao, Yuhang Qin, Yi Zhou, Yinghua Lu i Wenyao Shao. "Thin-Film Nanocomposite Reverse Osmosis Membrane with High Flux and Antifouling Performance via Incorporating Maleic Anhydride-Grafted Graphene Oxide". Advances in Polymer Technology 2022 (22.08.2022): 1–8. http://dx.doi.org/10.1155/2022/4177619.

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Water flux is one of the most important performance parameters of the reverse osmosis (RO) membrane. The higher water flux means lower energy cost when treating the same volume of feed solution with membrane separation technology. However, the increase of membrane water flux always corresponds to the decrease of solvent rejection, known as the “trade-off” effect. In addition, the surface fouling of membranes is often a serious problem, as frequent cleaning not only increases the operating cost but also shortens the life of the membranes. Recently, various hydrophilic nanomaterials have been used to improve the performance of membranes. To fabricate thin film nanocomposite (TFN) RO membrane with high flux and antifouling performance, maleic anhydride-grafted graphene oxide (MG) was successfully synthesized and incorporated into the polyamide (PA) layer via the interfacial polymerization (IP) method. We performed the IP reaction with m-phenylenediamine (MPD) and trimesoyl chloride (TMC) as reactive monomers on a polysulfone (PSF) substrate, and acid absorbent (TEA) and surfactant (SDS) were added to improve the separation performance of the membrane. The effects of MG incorporation on the membrane morphology and separation performance were investigated. SEM and AFM results show that the surface of the MG membrane is rougher than that of the membrane without MG. In addition, excessive loading of MG will lead to aggregation of MG nanosheets. FT-IR spectra indicate that the interaction between MG and PA layers results in an increase of hydrophilic groups on the surface of the TFN membrane, which is further confirmed by the results of the contact angle. The optimal MG doping concentration in the aqueous solution is 0.004 wt%, the water flux of the resultant TFN membrane is significantly increased to 51 L·m-2·h-1, 150% higher than the blank control membrane, which also performs a higher NaCI rejection (97.5% vs. 96.6%). Furthermore, the MG-incorporated RO membrane exhibits superior antifouling performance compared with the blank control membrane.

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Mahani, Nosrat, Fatemeh Mostaghni i Homa Shafiekhani. "GRAPHEN-PHENYL-NH2 AS NANOCARRIER: A DENSITY FUNCTIONAL THEORY STUDY". Química Nova, 2022. http://dx.doi.org/10.21577/0100-4042.20170865.

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Recently, graphene and modified graphene as one of the most suitable and the most important carbon nanomaterials have been introduced for drug delivery. In this paper, we have studied the binding characteristics of the EDC-NHS cross-linking process of graphene-phenyl-NH2 and 5-aminolevulinic acid (ALA) drug in both gas and solvent phases by density functional theory calculations. For describing binding properties and reaction nature between graphene-ghenyl-NH2 and ALA drug, quantum molecular descriptors, topological analysis, natural bond orbital analysis, analysis of the bond order, the density of states, and analysis bond length was investigated in solvent and gas phases. Due to the results, the complex of the graphene-phenyl-NH2 @ALA turns to absorb more electrons in water solvent than gas phase. Furthermore, the binding of graphene-phenyl-NH2 and ALA is mainly based on covalent interactions, and bond order of graphene-phenyl-NH2 @ALA complex is one in solvent and gas phases. The praphene-phenylNH2 @ALA complex has displayed a meaningful improvement of electronic and structural properties. Therefore, it represented that praphene-phenyl-NH2 being combined with the ALA drug is appropriate for use in drug delivery.

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