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https://www.readbyqxmd.com/read/28432970/insights-into-key-factors-controlling-go-stability-in-natural-surface-waters
#1
Yang Gao, Xuemei Ren, Xiaoli Tan, Tasawar Hayat, Ahmed Alsaedi, Changlun Chen
The effects of pH, cations (Na(+), K(+), Mg(2+), Ca(2+) and Al(3+)), and anions (Cl(-), HCO3(-), HPO4(2-) and SO4(2-)) on graphene oxide (GO) stability were investigated to address the current limitations in the knowledge regarding the stability of GO in natural surface water and its underlying mechanism. The threshold values of cations that destabilize GO were obtained and affected by both pH and anions. By employing elemental mapping and studying the effects of polyacrylic acid (PAA) on GO sedimentation and the re-dispersion of GO aggregates, we find that the GO aggregates induced by Na(+) and K(+) via electric double layer suppression and by Ca(2+) and Al(3+) via strong complxing are difficult to re-disperse completely...
April 11, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28431388/retention-and-transport-of-graphene-oxide-in-water-saturated-limestone-media
#2
Shunan Dong, Yuanyuan Sun, Bin Gao, Xiaoqing Shi, Hongxia Xu, Jianfeng Wu, Jichun Wu
In this work, column experiments were conducted to investigate the transport characteristics of graphene oxide (GO) nanoparticles in limestone media under various electrolytes, solution pH, and humic acid (HA) concentration conditions. In the limestone media, GO exhibited relatively low mobility with the mass recovery rate lower than 65.2%, even when solution ionic strength was low. The presence of HA enhanced its mobility. In addition, the presence of S(2-), a divalent anion, also promoted GO transport in limestone media compared to Cl(-) under similar ionic strength conditions through neutralizing more positive charge and thus diminishing the cation bridging...
April 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28431217/reduced-graphene-oxide-as-an-effective-adsorbent-for-removal-of-malachite-green-dye-plausible-adsorption-pathways
#3
Kanika Gupta, Om P Khatri
Efficient removal of malachite green (MG) dye from simulated wastewater is demonstrated using high surface area reduced graphene oxide (rGO). The plausible interaction pathways between MG dye and rGO are deduced from nanostructural features (HRTEM) of rGO and spectroscopic analyses (FTIR and Raman). The high surface area (931m(2)⋅gm(-1)) of rGO, π-π interaction between the aromatic rings of MG dye and graphitic skeleton, and electrostatic interaction of cationic centre of MG dye with π-electron clouds and negatively charged residual oxygen functionalities of rGO collectively facilitate the adsorption of MG dye on the rGO...
April 12, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28431216/synthesis-and-loading-dependent-characteristics-of-nitrogen-doped-graphene-foam-carbon-nanotube-manganese-oxide-ternary-composite-electrodes-for-high-performance-supercapacitors
#4
Tao Cheng, Baozhi Yu, Linli Cao, Huiyun Tan, Xinghua Li, Xinliang Zheng, Weilong Li, Zhaoyu Ren, Jinbo Bai
The ternary composite electrodes, nitrogen-doped graphene foam/carbon nanotube/manganese dioxide (NGF/CNT/MnO2), have been successfully fabricated via chemical vapor deposition (CVD) and facile hydrothermal method. The morphologies of the MnO2 nanoflakes presented the loading-dependent characteristics and the nanoflake thickness could also be tuned by MnO2 mass loading in the fabrication process. The correlation between their morphology and electrochemical performance was systematically investigated by controlling MnO2 mass loading in the ternary composite electrodes...
April 18, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28430445/controlling-the-roughness-of-langmuir-blodgett-monolayers
#5
Gregory J Silverberg, Arthur A McClelland, Sarah Griesse-Nascimento, Camille Girabawe, Julian P Kadow, Lakshminarayanan Mahadevan, Chad David Vecitis
Controlling the surface roughness of thin films with nanoscale precision is of significant interest for the rational design of surface coatings. Although wrinkling and buckling of Langmuir monolayers under compression has been demonstrated for several years, there is currently no method to precisely control this behavior during compression and thereby modify the surface roughness of deposited films. Here, we combine conventional Langmuir phase analysis with a novel dynamic viscoelasticity measurement to simply and accurately observe the jamming transition of monolayers of silica spheres, graphene oxide, and surfactant...
April 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28430346/facile-synthesis-of-reduced-graphene-oxide-fe3o4-nanocomposite-film
#6
Cunqing Ma, Kaiyu Yang, Lili Wang, Xin Wang
BACKGROUND: This study aims at proposing a facile method to prepare rGO/Fe3O4 composite film with adjusted magnetic properties and electronic conductivity. METHODS: Colloidal solution of graphene oxide (GO)/Fe3O4 nanoparticles (F-NPs) with a size in the range of 20-80 nm were prepared by a solution-blending method and heated step-by-step from room temperature to 60°C, 120°C and 160°C for 12 hours, respectively, to obtain a reduced graphene oxide (rGO)/F-NP composite film...
April 20, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28430276/understanding-gas-adsorption-in-mof-5-graphene-oxide-composite-materials
#7
Li-Chiang Lin, Dooam Paik, Jihan Kim
Metal-organic framework (MOF) and graphene oxide (GO) composite materials (MOF/GO) have been regarded as promising for separation applications due to their synergistically enhanced adsorption properties. Molecular-level understandings of these materials, however, remain unknown to date. In this study, molecular simulations were used, for the first time, to model these composite materials. Specifically, the composite MOF-5/GO material was modeled as stacks of sandwich-like layers on top of one another, consistent with experimental observations inferred from XRD and the SEM images...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28430273/the-interfacing-structural-effect-of-ag-graphene-oxide-nanohybrid-films-on-surface-enhanced-raman-scattering
#8
Young-Kwan Kim, Gyeongsik Ok, Sung-Wook Choi, Hongje Jang, Dal-Hee Min
The interfacing structural effect of Ag/graphene oxide (GO) nanohybrid films on SERS was investigated by using Ag nanostructures immobilized on polyallylamine hydrochloride (PAA) functionalized-GO and reduced GO (RGO) films. We found that the electron transfer from Ag nanostructures to GO derivatives dominantly occurred at the interfaces between Ag nanostructures and the sp(2) carbon domains of GO and RGO films. By utilizing 4-aminothiophenol (4-ATP) as a Raman probe, it was revealed that this electron transfer process augmented the enhancement factor (EF) of 4-ATP up to ∼1...
April 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/28430221/numerical-simulation-on-the-performance-analysis-of-a-graphene-coated-optical-fiber-plasmonic-sensor-at-anti-crossing
#9
Jeeban Kumar Nayak, Rajan Jha
A graphene-based surface plasmon resonance sensor using D-shaped fiber in anti-crossing has been designed. Silver as a plasmon active metal is followed by graphene, which helps in preventing oxidation and shows better adsorption efficiency to biomolecules. A wavelength interrogation technique based on the finite element method has been used to evaluate performance parameters. Design parameters such as thickness of silver, residual cladding, and GeO<sub>2</sub> dopant concentration have been optimized...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28429929/flexible-paper-like-free-standing-electrodes-by-anchoring-ultrafine-sns2-nanocrystals-on-graphene-nanoribbons-for-high-performance-sodium-ion-batteries
#10
Yang Liu, Yongzhen Yang, Xuzhen Wang, Yanfeng Dong, Yongchao Tang, Zhengfa Yu, Zongbin Zhao, Jieshan Qiu
Ultrafine SnS2 nanocrystals/reduced graphene oxide nanoribbon paper (SnS2/RGONRP) has been created by a well-designed process including in situ reduction, evaporation induced self-assembly and sulfuration. The as formed SnS2 nanocrystals possess an average diameter of 2.3 nm and disperse on the surface of RGONRs uniformly. The strong capillary force formed during evaporation leads to a compact assembly of RGONRs to give flexible paper structure with high density of 0.94 g cm-3. The as-prepared SnS2/RGONRP composite could be directly used as free-standing electrode for sodium ion batteries...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28429736/single-step-one-pot-synthesis-of-tio2-nanosheets-doped-with-sulfur-on-reduced-graphene-oxide-with-enhanced-photocatalytic-activity
#11
Weilin Wang, Zhaofeng Wang, Jingjing Liu, Zhu Luo, Steven L Suib, Peng He, Guqiao Ding, Zhengguo Zhang, Luyi Sun
A hybrid photocatalyst based on anatase TiO2 was designed by doping TiO2 with sulfur and incorporating reduced graphene oxide (TiO2-S/rGO hybrid), with an aim to narrow the band gap to potentially make use of visible light and decrease the recombination of excitons, respectively. This TiO2-S/rGO hybrid was successfully synthesized using a one-pot hydrothermal method via single-step reaction. The structure and morphology of the TiO2-S/rGO hybrid catalyst was carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS)...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28429523/poly-cytosine-dna-as-a-high-affinity-ligand-for-inorganic-nanomaterials
#12
Chang Lu, Zhicheng Huang, Biwu Liu, Yibo Liu, Yibin Ying, Juewen Liu
Attaching DNA to nanomaterials is the basis for DNA-directed assembly, sensing, and drug delivery using such hybrid materials. Poly-cytosine (poly-C) DNA is a high affinity ligand for four types of commonly used nanomaterials, including nanocarbons (graphene oxide and single-walled carbon nanotubes), transition metal dichalcogenides (MoS2 and WS2 ), metal oxides (Fe3 O4 and ZnO), and metal nanoparticles (Au and Ag). Compared to other homo-DNA sequences, poly-C DNA has the highest affinity for the first three types of materials...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28429506/a-robust-and-conductive-black-tin-oxide-nanostructure-makes-efficient-lithium-ion-batteries-possible
#13
Wujie Dong, Jijian Xu, Chao Wang, Yue Lu, Xiangye Liu, Xin Wang, Xiaotao Yuan, Zhe Wang, Tianquan Lin, Manling Sui, I-Wei Chen, Fuqiang Huang
SnO2 -based lithium-ion batteries have low cost and high energy density, but their capacity fades rapidly during lithiation/delithiation due to phase aggregation and cracking. These problems can be mitigated by using highly conducting black SnO2-x , which homogenizes the redox reactions and stabilizes fine, fracture-resistant Sn precipitates in the Li2 O matrix. Such fine Sn precipitates and their ample contact with Li2 O proliferate the reversible Sn → Li x Sn → Sn → SnO2 /SnO2-x cycle during charging/discharging...
April 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28429029/derivatization-and-interlaminar-debonding-of-graphite-iron-nanoparticle-hybrid-interfaces-using-fenton-chemistry
#14
Neha Agarwal, Ruma Bhattacharyya, Narendra K Tripathi, Sanjay Kanojia, Debmalya Roy, Kingsuk Mukhopadhyay, Namburi Eswara Prasad
The interfacial debonding of graphite lattices using iron (Fe) nanoparticles and Fenton's reagent is reported, towards the scalable production of few-layer graphene flakes. Acoustic cavitation via a sonochemical route was adapted to produce iron and iron oxide nanoparticles in the graphite matrix. The oxygenated species were introduced into the graphite lattice using a physical method, and then Fenton chemistry was utilized to generate localized hydroxyl radicals at the Fe nanoparticle-graphite interfaces for zipping and self-exfoliation of the defected graphite lattices...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28427681/sonochemical-assisted-synthesis-of-rgo-zno-nanowire-arrays-for-photoelectrochemical-water-splitting
#15
Ibrahim Khan, Akram A M Ibrahim, Manzar Sohail, Ahsanulhaq Qurashi
This article presented the synthesis of a hybrid nanoarchitecture material composed of reduced graphene oxide (RGO) multiple sheets and ZnO nanowire arrays (NWAs) formed on an arbitrary ZnO coated fluorine doped tin oxide (FTO) substrates via pulse sonication and hydrothermal approach. The NWAs have high aspect-ratio, high density, apt positioning and well-ordered formation. FESEM images demonstrated that RGO layers have been effectively intercalated between and on the accessible surfaces of the ZnO NWAs. The diameter of ZnO nanowires is 80-150nm and length about 1-2μm...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427614/production-of-graphene-quantum-dots-by-ultrasound-assisted-exfoliation-in-supercritical-co2-h2o-medium
#16
Hanyang Gao, Chen Xue, Guoxin Hu, Kunxu Zhu
In this research, three kinds of graphene quantum dots (GQDs)-pristine graphene quantum dots (PGQDs), expanded graphene quantum dots (EGQDs) and graphene oxide quantum dots (GOQDs)-were produced from natural graphite, expanded graphite, and oxide graphite respectively in an ultrasound-assisted supercritical CO2 (scCO2)/H2O system. The effects of aqueous solution content ratio, system pressure, and ultrasonic power on the yields of different kinds of GQDs were investigated. According to these experiment results, the combination of the intense knocking force generated from high-pressure acoustic cavitation in a scCO2/H2O system and the superior penetration ability of scCO2 was considered to be the key to the successful exfoliation of such tiny pieces from bulk graphite...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28426072/in-situ-hybridization-of-coox-nanoparticles-on-n-doped-graphene-through-one-step-mineralization-of-co-responsive-hydrogels
#17
Jing Ma, Xiaojuan Wang, Ting He, Minli Tan, Jun Zheng, Huiqiong Wu, Mengying Yuan, Rujuan Shen, Yi Zhang, Juan Xiang
The in situ hydrothermal mineralization for a mixture of graphene oxide (GO) and Co-responsive supramolecular hydrogels led to a hybrid graphene aerogel, doped with Co and N elements. The as-prepared aerogels exhibited a competitive half-wave potential (0.840 V, versus RHE) and peak current density (2.35 mA cm(-2)) to that of Pt/C (0.836 V, 2.23 mA cm(-2), respectively). Furthermore, they demonstrated a significantly perfect catalytic efficiency (nearly 100% of 4e(-) ORR) toward the oxygen reduction reaction (ORR)...
April 20, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28425695/reduced-graphene-oxide-containing-smart-hydrogels-with-excellent-electro-response-and-mechanical-property-for-soft-actuators
#18
Chao Yang, Zhuang Liu, Chen Chen, Kun Shi, Lei Zhang, Xiao-Jie Ju, Wei Wang, Rui Xie, Liang-Yin Chu
A novel reduced graphene oxide/poly(2-acrylamido-2-methylpropane sulfonic acid-co-acrylamide) (rGO/poly(AMPS-co-AAm)) nanocomposite hydrogel that possesses excellent electro-response and mechanical property has been successfully developed. The rGO nanosheets that homogeneously dispersed in the hydrogels could provide prominent conductive platforms for promoting the ion transport inside the hydrogels to generate significant osmotic pressure between the external and internal of such nanocomposite hydrogels. Thus, the electro-responsive rate and degree of the hydrogel for both deswelling and bending performances become rapid and remarkable...
April 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28425621/p53-competent-cells-and-p53-deficient-cells-display-different-susceptibility-to-oxygen-functionalized-graphene-cytotoxicity-and-genotoxicity
#19
Dayton M Petibone, Thikra Mustafa, Shawn E Bourdo, Andersen Lafont, Wei Ding, Alokita Karmakar, Zeid A Nima, Fumiya Watanabe, Daniel Casciano, Suzanne M Morris, Vasily N Dobrovolsky, Alexandru S Biris
Due to the distinctive physical, electrical, and chemical properties of graphene nanomaterials, numerous efforts pursuing graphene-based biomedical and industrial applications are underway. Oxidation of pristine graphene surfaces mitigates its otherwise hydrophobic characteristic thereby improving its biocompatibility and functionality. Yet, the potential widespread use of oxidized graphene derivatives raises concern about adverse impacts on human health. The p53 tumor suppressor protein maintains cellular and genetic stability after toxic exposures...
April 20, 2017: Journal of Applied Toxicology: JAT
https://www.readbyqxmd.com/read/28425517/diels-alder-reactions-of-graphene-oxides-greatly-enhanced-chemical-reactivity-by-oxygen-containing-groups
#20
Shaobin Tang, Weihua Wu, Liangxian Liu, Zexing Cao, Xiaoxuan Wei, Zhongfang Chen
Graphene oxides (GOs) or reduced GOs (rGOs) may offer extraordinary potential for chemical functionalization of graphene due to their unique electronic and structural properties. By means of dispersion-corrected density functional theory computations, we systematically investigated the Diels-Alder (DA) chemistry of GOs. Our computations showed that the dual nature of GOs as both a diene and a dienophile is stronger than that of pristine graphene. Interestingly, the interior bonds of a graphene surface modified by oxygen-containing groups could be functionalized by maleic anhydride (MA) and 2,3-dimethoxybutadiene (DMBD) through cycloaddition reactions, and the cycloaddition products of MA and DMBD are more favorable than the non-covalent complexes between these reagents and the GO surface...
April 20, 2017: Physical Chemistry Chemical Physics: PCCP
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