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Functionalization of graphene

Tengfei Cao, David Cuffari, Angelo Bongiorno
A general method is presented to calculate from first principles the full set of third-order elastic constants of a material of arbitrary symmetry. The method here illustrated relies on a plane-wave density functional theory scheme to calculate the Cauchy stress and the numerical differentiation of the second Piola-Kirchhoff stress tensor to evaluate the elastic constants. It is shown that finite difference formulas lead to a cancellation of the finite basis set errors, whereas simple solutions are proposed to eliminate numerical errors arising from the use of Fourier interpolation techniques...
November 23, 2018: Physical Review Letters
Samanta Witomska, Włodzimierz Czepa, Zhaoyang Liu, Alessandro Aliprandi, Dawid Pakulski, Piotr Pawluc, Artur Ciesielski, Paolo Samorì
Towards the introduction of fast faradaic pseudocapacitive behavior and the increase of the specific capacitance of carbon-based electrodes, we have covalently functionalized graphene oxide with a redox active thiourea-formaldehyde polymer yield-ing a multifunctional hybrid system. The multiscale physical and chemical characterization of the novel 3-dimensional hy-brid revealed high material's porosity with high specific surface area (402 m2 g-1) and homogeneous element distribution. The presence of multiple functional groups comprising sulphur, nitrogen and oxygen, provide additional contribution of Faradic redox reaction in supercapacity performance, leading to a high effective electrochemical pseudocapacitance...
December 5, 2018: Journal of the American Chemical Society
Jiří Tuček, Katerina Hola, Giorgio Zoppellaro, Piotr Blonski, Rostislav Langer, Miroslav Medved, Toma Susi, Michal Otyepka, Radek Zbořil
Stabilization of ferromagnetic ordering in graphene-based systems up to room temperature remains an important challenge owing to huge scope for applications in electronics, spintronics, biomedicine, and separation technologies. To date, several strategies have been proposed, including edge engineering, introduction of defects and dopants, and covalent functionalization. However, these techniques are usually hampered by limited temperature sustainability of ferromagnetic ordering. Here, we describe a method for the well-controlled sp3 functionalization of graphene to synthesize zig-zag conjugated sp2 carbon chains that can act as communication pathways among radical motifs...
December 5, 2018: ACS Nano
Un Jeong Kim, Jun Suk Kim, Noejung Park, Sanghyub Lee, Ukjae Lee, Yeonsang Park, Jinbong Seok, Sungwoo Hwang, Hyungbin Son, Young Hee Lee
Metal/graphene interface has been one of the most important research topics with regard to charge screening, charge transfer, contact resistance, and solar cells. Chemical bond formation of metal/graphene can be deduced from the defect induced D-band and its second-order mode, 2D band, measured by Raman spectroscopy, as a simple and non-destructive method. However, a phonon mode located at ~ 1350 cm-1 , which is normally known as the defect-induced D-band, is intriguing for graphene deposited with noble metals (Ag, Au, and Cu)...
December 5, 2018: ACS Nano
Yinghong Xiao, Ming Zhang, Yunting Fan, Qicheng Zhang, Yuli Wang, Wenwen Yuan, Ninglin Zhou, Jianfei Che
A novel drug carrier is constructed by compositing hydrophilic hydroxypropyl-β-cyclodextrins (HP-β-CD) and carboxylated graphene nanomaterial (GO-COOH). Fourier transform infrared spectroscopy confirms that the two materials are successfully combined via chemical bonds. Further, a crosslinking agent of glutaraldehyde is applied to fabricate composite GO-COO-HP-β-CD nanospheres, as demonstrated by an atomic force microscope. Dexamethasone (DEX) is selected as the model drug, and the drug loading efficiency and water solubility of the nanospheres greatly increased...
November 28, 2018: Colloids and Surfaces. B, Biointerfaces
Yao Huang, Yanyan Gong, Jingchun Tang, Siyu Xia
A novel thiol-functionalized graphene oxide/Fe-Mn (SGO/Fe-Mn) was investigated for aqueous Hg2+ and CH3 Hg+ removal. Mercury were removed mainly through ligand exchange and surface complexation with surface active sites (i.e., -SH, OH, OCO, CC, SiO, and ππ bond). SH had the strongest binding ability with mercury, forming sulfur-containing organic matter or polymers with Hg2+ , and sulfur-containing organometallic compounds or thiolate-like species with CH3 Hg+ . The BET sorption isotherm model well simulated the sorption isotherm data of Hg2+ (R2 =0...
November 18, 2018: Journal of Hazardous Materials
Carol Korzeniewski, Jay P Kitt, Saheed Bukola, Stephen E Creager, Shelley D Minteer, Joel M Harris
Single layer graphene (SLG), with its angstrom-scale thickness and strong Raman scattering cross section, was adapted for measurement of the axial (Z-direction) probe beam profile in confocal Raman microscopy depth-profiling experiments. SLG adsorbed to a glass microscope coverslip (SLG/SiO2 ) served as a platform for estimation of axial spatial resolution. Profiles were measured by stepping the confocal probe volume through the SLG/SiO2 interface while measuring Raman scattering from the sample. Using a high numerical aperture (1...
December 4, 2018: Analytical Chemistry
Xiong Su, Xiao-Feng Yang, Yanqiang Huang, Bin Liu, Tao Zhang
Simply yet powerfully, single-atom catalysts (SACs) with atomically dispersed metal active centers on supports have received a growing interest in a wide range of catalytic reactions. As a specific example, SACs have exhibited distinctive performances in CO2 chemical conversions. The unique structures of SACs are appealing for adsorptive activation of CO2 molecules, transfer of intermediates from support to active metal sites, and production of desirable products in CO2 conversion. In this Account, we have exemplified our recent endeavors in the development of SACs toward CO2 conversions in thermal catalysis and electrocatalysis...
December 4, 2018: Accounts of Chemical Research
Yang Li, Xue-Yin Sun, Cheng-Yan Xu, Jian Cao, Zhao-Yuan Sun, Liang Zhen
Integrating two-dimensional (2D) materials with ferroelectric thin films may result in unique characteristics and novel applications due to the coupling between their intrinsic characters. Here, we observed the ferroelectric resistive switching behavior in both graphene/BFO and MoS2/BFO heterojunctions, which stems from the modulation of contact barriers and depletion width at the hetero-interface induced by the ferroelectric polarization. Besides, the ferroelectric resistive switching behavior in both graphene/BFO and MoS2/BFO depends on the thicknesses of the corresponding 2D materials, because the thickness-dependent work function or conductivity of 2D materials could change the contact barrier heights and widths at the interface of 2D materials and ferroelectrics...
December 4, 2018: Nanoscale
Li Zhao, Jingting Kong, Natalia Krasteva, Dayong Wang
The developmental basis for the epidermal barrier against the translocation of nanomaterials is still largely unclear in organisms. We here investigated the effect of deficits in the epidermal barrier on the translocation and toxicity of PEG modified graphene oxide (GO-PEG) in Caenorhabditis elegans . In wild-type or NR222 nematodes, GO-PEG exposure did not cause toxicity and affect the expression of epidermal-development related genes. However, GO-PEG exposure resulted in toxicity in mlt-7(RNAi) nematodes with deficit in the function of epidermal barrier...
November 1, 2018: Toxicology Research
Hina Javed, Aminul Islam, Anjali Chauhan, Suneel Kumar, Sushil Kumar
Graphene oxide (GO) was immobilized innovatively through azo spacer arm onto the surface of polymeric Amberlite XAD-16 resin in order to expose all oxygen functionalities freely available for metal ions coordination and further modification with picolylamine which governs selectivity. The GO Amberlite XAD-16 picolylamine enables the development of SPE column coupled with ICP-OES for preconcentration and determination of Pb (II) and Cu (II) in water and fish samples. Elution was performed by mild acid (2M HCl) no other carcinogenic organic solvent was used, prevents ligand leaching...
December 3, 2018: Scientific Reports
Hyo Won Kim, Wonhee Ko, Won-Jae Joo, Yeonchoo Cho, Youngtek Oh, JiYeon Ku, Insu Jeon, Seongjun Park, Sungwoo Hwang
The direct growth of graphene on a semiconducting substrate opens a new avenue for future graphene-based applications. Understanding the structural and electronic properties of the graphene on a semiconducting surface is key for realizing such structures; however, these properties are poorly understood thus far. Here, Here, we provide an insight into the structural and electronic properties of graphene grown directly on a Ge(110) substrate. Our scanning tunneling microscopy (STM) study reveals that overlaying graphene on Ge(110) promotes the formation of a new Ge surface reconstruction, i...
December 4, 2018: Journal of Physical Chemistry Letters
Yan Chen, Xiuqiang Xie, Xin Xin, Zi-Rong Tang, Yi-Jun Xu
Assembly of two-dimensional (2D) layered structures into three-dimensional (3D) macroscopic hydrogel has been an enduring attracting research theme. However, the anisotropic intersheet cross-linking to form Ti3C2Tx MXene-based hydrogel remains intrinsically challenging because of the superior hydrophilic nature of 2D Ti3C2Tx. Herein, Ti3C2Tx MXene is ingeniously assembled into the 3D macroscopic hydrogel under mild conditions by a graphene oxide (GO) assisted self-convergence process. During the process, GO is reduced to reduced graphene oxide (RGO) by virtue of the reduction ability of Ti3C2Tx, leading to the partial removal of hydrophilic oxygen-containing groups and an increase of the hydrophobicity and the π-conjugated structures of RGO, which enables the assembly of RGO into 3D RGO framework...
December 3, 2018: ACS Nano
Kairi Yamato, Ryo Sekiya, Manabu Abe, Takeharu Haino
Excitation-dependent photoluminescence (PL) is well-known property of graphene quantum dots (GQDs). For the development of carbon-based photo-functional materials, GQDs possessing uniform PL properties are highly demanded. We established a protocol to separate spectroscopically uniform lipophilic GQD-1a from a GQD-1 mixture mainly composed of GQD-1a and GQD-1b. The GQD-1 mixture was synthesized by the reaction of p-methoxybenzyl amine with GQD-2 prepared from graphite by common oxidative exfoliations. Size exclusion chromatography gave raise to GQD-1a and GQD-1b with diameters of 19...
December 2, 2018: Chemistry, An Asian Journal
Shengjie Ling, Qi Wang, Dong Zhang, Yingying Zhang, Xuan Mu, David L Kaplan, Markus J Buehler
The production of structural and functional materials with enhanced mechanical properties through the integration of soft and hard components is a common approach to Nature's materials design. However, directly mimicking these optimized design routes in the lab for practical applications remains challenging. For example, graphene and silk are two materials with complementary mechanical properties that feature ultrahigh stiffness and toughness, respectively. Yet no simple and controllable approach has been developed to homogeneously integrate these two components into functional composites, mainly due to the hydrophobicity and chemical inertness of the graphene...
February 28, 2018: Advanced Functional Materials
Niloufar Nekouei Marnani, Afsaneh Shahbazi
The synergistic combination of two different environmentally friendly functional groups (EDTA and Chitosan) with magnetic graphene oxide (mGO) nano-sheets was used for synthesizing a promising nanobiocomposite adsorbent (CS-EDTA-mGO) for efficient removal of a cationic dye, Rhodamine B (RhB), from aqueous solutions. CS-EDTA-mGO nanobiocomposite was characterized by XRD, FTIR, VSM, TGA, and zeta potential. Further, the morphological features of the synthesized graphene oxide and mGO were examined by SEM technique...
November 16, 2018: Chemosphere
Ana Domínguez-Bajo, Ankor González-Mayorga, Carlos R Guerrero, F Javier Palomares, Ricardo García, Elisa López-Dolado, María Concepción Serrano
Neural diseases at the central nervous system including spinal cord injury (SCI) remain therapeutic challenges. Graphene materials are being delineated as alternative tools for neural repair. Herein, the regenerative ability of reduced graphene oxide (rGO) scaffolds to support pivotal features of neural repair at 4 months after SCI is assessed by an interdisciplinary approach. 3D randomly porous foams have been prepared in mechanical compliance with neural cells and tissues (Young's modulus of 1.3 ± 1...
November 19, 2018: Biomaterials
Dongdong Gao, Yirui Wang, Yi Liu, Huiping Sun, Minghong Wu, Haijiao Zhang
The interfacial engineering plays an important role in enhancing the electrochemical properties of graphene-based hybrid materials for energy conversion and storage. Herein, we propose a facile interfacial engineering route for achieving a novel type of SnS2 /N-doped graphene (SnS2 /NG) composite with superior lithium storage capability. Interestingly, the SnS2 particles formed show two totally different morphologies including ultrasmall nanoparticles about 5 nm and ultrathin nanosheets, and they are strongly coupled with nitrogen-doped graphene, giving rise to a unique 0D/2D heterostructure...
November 26, 2018: Journal of Colloid and Interface Science
Qiang Tan, Jie Qiu, Xiang Luo, Yuquan Chen, Yuting Liu, Haihong Wei, Ruochen Lu, Dongmei Wu
Graphene oxide has been widely used in biological applications because of good biocompatibility. In the present work, graphene oxide was synthesized successfully and was employed to immobilize glutaryl-7-aminocephalosporanic acid acylase (GLA). The immobilization conditions like pH, temperature, immobilization time, and enzyme/carrier ratio were investigated. Under the optimal immobilization conditions, the immobilization yield and efficiency were 86% and 52%, respectively. The characterization of the immobilized GLA was performed and compared with the free enzyme...
May 1, 2019: Journal of Nanoscience and Nanotechnology
Violetta Kozik, Andrzej Bak, Danuta Pentak, Barbara Hachula, Katarzyna Pytlakowska, Marcin Rojkiewicz, Josef Jampilek, Karolina Sieron, Joanna Jazowiecka-Rakus, Aleksander Sochanik
Chemically functionalized graphene oxides could be used as novel drug carriers. Covalent alterations of graphene oxides lead to surface changes via formation of chemical bonding while non-covalent ones involve van der Waals forces, hydrogen bonding, and π - π stacking interactions. Covalent modifications appear to be superior as they can yield compounds with desired properties and carriers prepared by other methods are less stable. Synthesis of graphene oxide-iminodiacetic acid and graphene oxide-glycine involves nucleophilic substitution of graphene oxide nanoparticles with iminodiacetic acid or glycine...
May 1, 2019: Journal of Nanoscience and Nanotechnology
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