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Functionalization of graphene

Aida Mohammadi, Danielle Lilly Nicholls, Aristides Docoslis
This study examines the improvements in surface-enhanced Raman scattering (SERS) performance achieved when silver nanodendritic structures are coated with various graphene-based materials, namely graphene oxide (GO), reduced graphene oxide (rGO), and graphene nanoplatelets (GNPs). The tests are performed on our unique SERS-active substrates, prepared on the surface of planar microelectrode chips using an electric field-guided Ag nanoparticle assembly process. The graphene-based materials are introduced into the substrate by means of an in-house spray-coating technique...
October 11, 2018: Sensors
Hui Xu, Yang Li, Neng-Jian Huang, Zhi-Ran Yu, Peng-Huan Wang, Zhao-Hui Zhang, Qiao-Qi Xia, Li-Xiu Gong, Shi-Neng Li, Li Zhao, Guo-Dong Zhang, Long-Cheng Tang
Fire prevention and safety of combustible materials is a global challenge. To reduce their high fire risk, traditional smoke detectors are widely used indoor via detecting smoke product after combustion; however, they usually show a long response time and limitation for outdoor use. Herein, we report a temperature-induced electrical resistance transition of graphene oxide wide-ribbon (GOWR) wrapped sponges to reliably monitor fire safety of the combustible materials. Novel rectangle-like GOWR sheets are synthesized from unzipping carbon nanofibers and used to fabricate GOWR wrapped melamine formaldehyde sponges with multi-functionalities, e...
October 1, 2018: Journal of Hazardous Materials
Jyoti Katoch, Tiancong Zhu, Denis Kochan, Simranjeet Singh, Jaroslav Fabian, Roland K Kawakami
We report the experimental observation of sublattice-resolved resonant scattering in bilayer graphene by performing simultaneous cryogenic atomic hydrogen doping and electron transport measurements in an ultrahigh vacuum. This allows us to monitor the hydrogen adsorption on the different sublattices of bilayer graphene without atomic-scale microscopy. Specifically, we detect two distinct resonant scattering peaks in the gate-dependent resistance, which evolve as a function of the atomic hydrogen dosage. Theoretical calculations show that one of the peaks originates from resonant scattering by hydrogen adatoms on the α sublattice (dimer site) while the other originates from hydrogen adatoms on the β sublattice (nondimer site), thereby enabling a method for characterizing the relative sublattice occupancy via transport measurements...
September 28, 2018: Physical Review Letters
Yupeng Sun, Kaixiang Zhang, Ruijie Deng, Xiaojun Ren, Can Wu, Jinghong Li
The stiffness of the extracellular matrix (ECM) not only provides mechanical resistance to support the cellular shape, but also plays significant roles in many cell functions. However, it's difficult to utilize traditional substrate materials to investigate cell behaviors under physical microenvironments due to their unphysiological stiffness or intrinsic secondary effects. Herein, a stiffness-tunable graphene oxide/polyacrylamide composite scaffold was fabricated to investigate the effect of substrate stiffness on cytoskeleton assembly and specific gene expression during cell growth...
August 21, 2018: Chemical Science
Qiaoping Kong, Jingyue Wei, Yun Hu, Chaohai Wei
In order to increase the density and quantity of functional groups on adsorbent, three terminal amino hyperbranched polymer modified graphene oxide adsorbents including GO-HBP-NH2 -DETA, GO-HBP-NH2 -TETA and GO-HBP-NH2 -TEPA with N-containing functional group density of 7.21 wt%, 10.20 wt% and 12.43 wt%, respectively, were prepared and used for the adsorption and reduction of toxic hexavalent chromium Cr(VI) to less toxic Cr(III). The morphology and structure of obtained adsorbents were characterized by FT-IR, SEM, XRD, Raman, BET, XPS and zeta potential...
October 1, 2018: Journal of Hazardous Materials
Wenzong Xu, Xiaoling Wang, Yun Wu, Wu Li, Chunying Chen
In order to reduce the fire risk of epoxy resin (EP), functionalized reduced graphene oxide (RGO) with Co-ZIF (zeolitic imidazolate frameworks-67) adsorbed borate ions (ZIF-67/RGO-B) was prepared. The results of transmission electron microscopy (TEM) showed that ZIF-67 was grown on the surface of RGO triumphantly. In addition, the structure of ZIF-67/RGO-B was not significantly changed compared with ZIF-67/RGO. Subsequently, ZIF-67/RGO-B was added into EP by a simple blending method. The combustion results showed that the heat and smoke production of EP composites were obviously reduced...
October 2, 2018: Journal of Hazardous Materials
Deepak Kumar, Thillai Govindaraja, Sailaja Krishnamurty, Selvaraj Kaliaperumal, Sourav Pal
Using periodic density functional theory-based calculations, in the present study, we address the chemical bonding between aluminium clusters (Aln, n = 4-8 and 13) and monovacant defective graphene. The adsorption strength of the above-mentioned aluminium clusters is fivefold (∼3 to 5 eV) higher on defective graphene as compared to the earlier reported values on non-defective graphene and BN-doped graphene. The Bader charge analysis and different charge densities reveal that this adsorption is driven by significant charge transfer from the Al clusters to defective graphene...
October 11, 2018: Physical Chemistry Chemical Physics: PCCP
Qiaoqiao Han, Lei Chen, Wenxiao Li, Zhiyong Zhou, Zhou Fang, Zhiwei Xu, Xiaoming Qian
Three-dimensional (3D) double network graphene oxide/polyacrylic acid (GO/PAA) hybrid aerogels were fabricated under mild conditions from the mixture of GO and acrylic acid (AA) monomers using a one-pot in situ solution polymerization process which included the polymerization of AA and the self-assembly of functional GO sheets. The PAA chains served as not only binder to assemble GO sheets into 3D framework but also modifier to provide more active functional groups. The adsorbents based on such material exhibited superior adsorption performance towards Cu2+ ions in aqueous media due to rich mesopores, high specific surface area, and abundant active sites...
October 10, 2018: Environmental Science and Pollution Research International
Ranganathan Krishnan, Shiuan-Yau Wu, Hsin-Tsung Chen
The catalytic reaction of carbon monoxide oxidation on boron-doped and boron-nitrogen co-doped penta-graphene materials has been systematically studied by utilizing spin-polarized density functional theory (DFT) calculations. Various pathways including the Eley-Rideal (ER), Langmuir-Hinshelwood (LH), and tri-molecular Eley-Rideal (TER) mechanisms were considered in which the TER mechanism is a newly proposed reaction mechanism for CO oxidation. According to the calculation results, the ER, LH and TER mechanisms of CO oxidation can occur and compete with each other because of the related small overall reaction energy barriers (0...
October 11, 2018: Physical Chemistry Chemical Physics: PCCP
Sekaran Saravanan, Niketa Sareen, Ejlal Abu-El-Rub, Hend Ashour, Glen Lester Sequiera, Hania I Ammar, Venkatraman Gopinath, Ashraf Ali Shamaa, Safinaz Salah Eldin Sayed, Meenal Moudgil, Jamuna Vadivelu, Sanjiv Dhingra
Abnormal conduction and improper electrical impulse propagation are common in heart after myocardial infarction (MI). The scar tissue is non-conductive therefore the electrical communication between adjacent cardiomyocytes is disrupted. In the current study, we synthesized and characterized a conductive biodegradable scaffold by incorporating graphene oxide gold nanosheets (GO-Au) into a clinically approved natural polymer chitosan (CS). Inclusion of GO-Au nanosheets in CS scaffold displayed two fold increase in electrical conductivity...
October 10, 2018: Scientific Reports
Qian Huang, Liying Hao, Ronghui Zhou, Bofeng Zhu, Hu Zhao, Xiaoxiao Cai
Graphitic-phase carbon nitride (g-C₃N₄) is a graphene analogue, which has attracted much attention for its unique physicochemical properties. The bulk g-C₃N₄ is often fragmented and ionized to nanosheets, obtaining improved performance or confer novel properties. It is reported that g-C₃N₄ nanosheets using different processing methods can be modified with different functional groups, resulting in different electrical characteristics. However, the surface charge of g-C₃N₄ nanosheets is seldom mentioned as a factor influencing their biological applications...
December 1, 2018: Journal of Biomedical Nanotechnology
Qian Zhang, Hua Deng, Hanjun Li, Keyi Song, Cheng Zeng, Ling Rong
Graphene oxide (GO) has attracted a wide attention for its excellent mechanical, thermal properties and unique two-dimensional structure. In this work, A new GO-based supramolecular hybrid nanohydrogel was prepared, in which GO as the cross-links was incorporated into the above hydrogel through non-covalent functionalization to enhance the mechanical properties and control morphology. A 1-pyrenebutyric acid (Py) modified low-molecular weight (MW) mPEG was firstly synthesized via a simple esterification reaction...
December 1, 2018: Journal of Biomedical Nanotechnology
Mingrui Guo, Yi Liu, Shun Dong, Xiuling Jiao, Ting Wang, Dairong Chen
Co9S8 crystals can catalyze the growth of thin-walled graphite microtubes (GMTs) via a catalytic chemical vapor deposition (CCVD) process using thiourea as the precursors. The growth of the GMTs follows a tip-growth mechanism with tube diameters up to a few microns. The hollow interiors of the GMTs are filled with carbon nanotubes and wrinkled graphene layers, form a unique nanotube/graphene-in-microtube structure. As-formed GMTs are N, S-codoped with lots of Co9S8 nanoparticles encapsulated in their inner walls...
October 10, 2018: ChemSusChem
Jiaxing Sun, Heng Chen, Dongxu Qi, Hao Wu, Changsong Zhou, Hongmin Yang
Graphene oxide (GO) is a new promising nanometer material in superconductor and wastewater heavy metal ions removal for its functionalized groups. Ethylenediaminetetraacetic acid functionalized graphene oxide complexes (EDTA-GO) was produced by a realizable silanization chemical reaction. Characteristics of Hg(II) removal in desulfurization wastewater was also under investigation. The chemical composition and microstructures of the EDTA-GO adsorbents were characterized by X-ray photoelectron spectroscopy (XPS), Transmission electron microscope (TEM), Scanning Electron Microscopy (SEM) analyses...
October 10, 2018: Environmental Technology
Tian Zhang, Hua Chai, Fanyu Meng, Zhenzhen Guo, Yu Jiang, Peng Miao
Herein, we have developed an ultrasensitive self-powered biosensor for miRNA assay based on biofuel cells (BFCs). The system is composed of indium tin oxide cathode and graphene oxide/gold nanoparticles/glucose oxidase anode. Redox probe of [Fe(CN)6]3- is entrapped inside porous Fe3O4 nanoparticles by DNA. However, in the presence of target miRNA, hybridization reaction occurs between miRNA and DNA, which initiates the release of [Fe(CN)6]3-. Moreover, duplex specific nuclease is further employed to trigger target recycling amplification...
October 10, 2018: ACS Applied Materials & Interfaces
Mohammed Noori, Hatef Sadeghi, Colin J Lambert
Nanoscale thermoelectricity is an attractive target technology, because it can convert ambient heat into electricity for powering embedded devices in the internet of things. We demonstrate that the thermoelectric performance of graphene nanoconstrictions can be significantly enhanced by the presence of stable radical adsorbates, because radical molecules adsorbed on the graphene nanoconstrictions create singly-occupied orbitals in the vicinity of Fermi energy. This in turn leads to sharp features in their transmission functions close to Fermi energy, which increases the electrical conductance and Seebeck coefficient of the nanoconstrictions...
October 10, 2018: Nanoscale
Dongliang Chao, Bo Ouyang, Pei Liang, Tran Thi Thu Huong, Guichong Jia, Hui Huang, Xinhui Xia, Rajdeep Singh Rawat, Hong Jin Fan
Tin and its derivatives have provoked tremendous progress of high-capacity sodium-ion anode materials. However, achieving high areal and volumetric capability with maintained long-term stability in a single electrode remains challenging. Here, an elegant and versatile strategy is developed to significantly extend the lifespan and rate capability of tin sulfide nanobelt electrodes while maintaining high areal and volumetric capacities. In this strategy, in situ bundles of robust hierarchical graphene (hG) are grown uniformly on tin sulfide nanobelt networks through a rapid (5 min) carbon-plasma method with sustainable oil as the carbon source and the partially reduced Sn as the catalyst...
October 9, 2018: Advanced Materials
Azam Akbarnia, Hamid R Zare
The authors describe a DNA based voltammetric assay for the cancer biomarker microRNA-25. A glassy carbon electrode (GCE) was modified with amino-functionalized graphene quantum dots and used as an amplifier of electrochemical signals. p-Biphenol is introduced as a new electroactive probe with a fairly low working potential of 0.3 V (vs. Ag/AgCl). The stages of fabricating the electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. ss-Probe DNA was immobilized on the modified GCE and then exposed to a sample containing microRNA-25...
October 9, 2018: Mikrochimica Acta
Jiuning Hu, Albert F Rigosi, Mattias Kruskopf, Yanfei Yang, Bi-Yi Wu, Jifa Tian, Alireza R Panna, Hsin-Yen Lee, Shamith U Payagala, George R Jones, Marlin E Kraft, Dean G Jarrett, Kenji Watanabe, Takashi Taniguchi, Randolph E Elmquist, David B Newell
We report the fabrication and measurement of top gated epitaxial graphene p-n junctions where exfoliated hexagonal boron nitride (h-BN) is used as the gate dielectric. The four-terminal longitudinal resistance across a single junction is well quantized at the von Klitzing constant [Formula: see text] with a relative uncertainty of 10-7 . After the exploration of numerous parameter spaces, we summarize the conditions upon which these devices could function as potential resistance standards. Furthermore, we offer designs of programmable electrical resistance standards over six orders of magnitude by using external gating...
October 9, 2018: Scientific Reports
Eunji Lee, Doohee Lee, Jaesik Yoon, Yilin Yin, You Na Lee, Sunil Uprety, Young Soo Yoon, Dong-Joo Kim
Few studies have investigated the gas-sensing properties of graphene oxide/titanium dioxide (GO/TiO₂) composite combined with photocatalytic effect. Room temperature gas-sensing properties of the GO/TiO₂ composite were investigated towards various reducing gases. The composite sensor showed an enhanced gas response and a faster recovery time than a pure GO sensor due to the synergistic effect of the hybridization, such as creation of a hetero-junction at the interface and modulation of charge carrier density...
October 5, 2018: Sensors
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