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Functionalization of graphene

Tung Pham, Guanghui Li, Elena Bekyarova, Mikhail E Itkis, Ashok Mulchandani
Red light illumination with photon energy matching the direct bandgap of CVD grown single-layer MoS2 with Au metal electrodes was used to induce a photocurrent which was employed instead of dark current for NO2 gas sensing. Resulted Au/MoS2 /Au optoelectronic gas sensor showed a significant enhancement of the device sensitivity S toward ppb level of NO2 gas exposure reaching S=4.8%/ppb (4800%/ppm), where S is a slope of dependence of relative change of the sensor resistance on NO2 concentration. Further optimization of the MoS2 based optoelectronic gas sensor by using a graphene (Gr) with lower work function than of Au for the electrical contacts to the MoS2 channel allowed an increase of photocurrent...
February 20, 2019: ACS Nano
Christopher D Williams, Paola Carbone, Flor R Siperstein
Graphene oxide (GO) membranes offer exceptional promise for certain aqueous separation challenges, such as desalination. Central to unlocking this promise and optimising performance for a given separation is the establishment of a detailed molecular-level understanding of how the membrane's composition affects its structural and transport properties. This understanding is currently lacking, in part due to the fact that, until recently, molecular models with a realistic distribution of oxygen-functionalities and interlayer flake structure were unavailable...
February 20, 2019: ACS Nano
Artur P Durajski, Kamil M Skoczylas, Radosław Szczśniak
With the enormous research activity focused on graphene in recent years, it is not surprising that graphene superconductivity has become an attractive area of research. To date, no superconducting properties have been experimentally observed in the pristine form of graphene but controllable structure manipulation is a promising way to induce a superconducting state in graphene-based systems. Therefore, herein we investigate the possible superconductivity in two-layer graphene intercalated with atoms of alkali and alkaline earth metals...
February 20, 2019: Physical Chemistry Chemical Physics: PCCP
Ji-Soo Jang, Hayoung Yu, Seon-Jin Choi, Won-Tae Koo, Jiyoung Lee, Dong-Ha Kim, Joon-Young Kang, Yong Jin Jeong, Hyeon Su Jeong, Il-Doo Kim
The development of freestanding fiber-type chemiresistor, having high integration ability with various portable electronics including smart clothing system, is highly demanding for the next-generation wearable sensing platform. However, critical challenges stemming from irreversible chemical sensing kinetics and weak reliability of the freestanding fiber-type chemiresistor hinder their practical use. In this work, for the first time, we report on potential suitability of the freestanding and ultraporous reduced graphene oxide fiber functionalized with WO3 nanorods (porous WO3 NRs-RGO composite fiber) as a sensitive nitrogen dioxide (NO2) detector...
February 20, 2019: ACS Applied Materials & Interfaces
Jung Hwa Kim, Se-Yang Kim, Yeonchoo Cho, Hyo Ju Park, Hyeon-Jin Shin, Soon-Yong Kwon, Zonghoon Lee
Van der Waals (vdW) epitaxy allows the fabrication of various heterostructures with dramatically released lattice matching conditions. This study demonstrates interface-driven stacking boundaries in WS2 using epitaxially grown tungsten disulfide (WS2 ) on wrinkled graphene. Graphene wrinkles function as highly reactive nucleation sites on WS2 epilayers; however, they impede lateral growth and induce additional stress in the epilayer due to anisotropic friction. Moreover, partial dislocation-driven in-plane strain facilitates out-of-plane buckling with a height of 1 nm to release in-plane strain...
February 20, 2019: Advanced Materials
Shabi Abbas Zaidi
Apart from being a vital catecholamine molecule responsible for the proper functioning of the central nervous system (CNS), hormonal and renal systems, dopamine (DA) has also been increasingly employed as a functional monomer in the fabrication of surface molecular imprinting polymers (MIPs) for valuable analytes. Herein, we demonstrate the effective imprinting of 6-thioguanine (6-TG), an anticancer drug, via mussel-inspired self-polymerization of dopamine conducted in a weakly alkaline solution over reduced graphene oxide (rGO)...
February 20, 2019: Analyst
Huai Li, Zifang Chi, Baixing Yan
The increasing application of engineered nanoparticles (NPs) has posed an emerging challenge to constructed wetland wastewater treatment. The performance, microbial community and toxic mechanism of anammox-based unplanted subsurface-flow constructed wetlands (USFCWs) were investigated under the long-term exposure of different graphene oxides (GOs) and Ag NP concentrations. Results showed that the addition of GO could promote TN removal, manifesting as function anammox bacteria C. Anammoxoglobus having a relative high abundance, for GO did not cause significant damage to the cell integrity though there was an increase in ROS concentrations...
May 2019: Journal of Environmental Sciences (China)
Hector Rosas-Hernandez, Claudia Escudero-Lourdes, Manuel A Ramirez-Lee, Elvis Cuevas, Susan M Lantz, Syed Z Imam, Waqar Majeed, Shawn E Bourdo, Merle G Paule, Alexandru S Biris, Syed F Ali
Graphene-based nanomaterials hold the potential to be used in a wide variety of applications, including biomedical devices. Pristine graphene (PG) is an un-functionalized, defect-free type of graphene that could be used as a material for neural interfacing. However, the neurotoxic effects of PG, particularly to the blood-brain barrier (BBB), have not been fully studied. The BBB separates the brain tissue from the circulating substances in the blood and is essential to maintain the brain homeostasis. The principal components of the BBB are brain microvascular endothelial cells (BMVECs), which maintain a protectively low permeability due to the expression of tight junction proteins...
February 19, 2019: Journal of Applied Toxicology: JAT
Joshua Avossa, Roberto Paolesse, Corrado Di Natale, Emiliano Zampetti, Giovanni Bertoni, Fabrizio De Cesare, Giuseppe Scarascia-Mugnozza, Antonella Macagnano
Structural and functional properties of polymer composites based on carbon nanomaterials are so attractive that they have become a big challenge in chemical sensors investigation. In the present study, a thin nanofibrous layer, comprising two insulating polymers (polystyrene (PS) and polyhydroxibutyrate (PHB)), a known percentage of nanofillers of mesoporous graphitized carbon (MGC) and a free-base tetraphenylporphyrin, was deposited onto an Interdigitated Electrode (IDE) by electrospinning technology. The potentials of the working temperature to drive both the sensitivity and the selectivity of the chemical sensor were studied and described...
February 17, 2019: Nanomaterials
Xiaoqing Yu, Shuwei Sun, Lin Zhou, Zhicong Miao, Xiaoyuan Zhang, Zhiqiang Su, Gang Wei
Here we report the fabrication of graphene oxide (GO)-based membranes covalently combined with bovine serum albumin (BSA) for metal ions detection. In this system, BSA acts as a transporter protein in the membrane and endows the membrane with selective recognition of Co2+ , Cu2+ , AuCl₄- , and Fe2+ . Combining the metal-binding ability of BSA and the large surface area of GO, the hybrid membrane can be used as a water purification strategy to selectively absorb a large amount of AuCl₄- from HAuCl₄ solution...
February 16, 2019: Nanomaterials
Ji Hye Lee, Sung Hyun Kwon, Soonchul Kwon, Min Cho, Kwang Ho Kim, Tae Hee Han, Seung Geol Lee
We calculated the band structures of a variety of N- and S-doped graphenes in order to understand the effects of the N and S dopants on the graphene electronic structure using density functional theory (DFT). Band-structure analysis revealed energy band upshifting above the Fermi level compared to pristine graphene following doping with three nitrogen atoms around a mono-vacancy defect, which corresponds to p-type nature. On the other hand, the energy bands were increasingly shifted downward below the Fermi level with increasing numbers of S atoms in N/S-co-doped graphene, which results in n-type behavior...
February 15, 2019: Nanomaterials
Eva Álvarez-Regueiro, Javier P Vallejo, José Fernández-Seara, Josefa Fernández, Luis Lugo
Convection heat transfer coefficients and pressure drops of four functionalized graphene nanoplatelet nanofluids based on the commercial coolant Havoline® XLC Pre-mixed 50/50 were experimentally determined to assess its thermal performance. The potential heat transfer enhancement produced by nanofluids could play an important role in increasing the efficiency of cooling systems. Particularly in wind power, the increasing size of the wind turbines, up to 10 MW nowadays, requires sophisticated liquid cooling systems to keep the nominal temperature conditions and protect the components from temperature degradation and hazardous environment in off-shore wind parks...
February 15, 2019: Nanomaterials
Wenquan Zhou, Jincheng Wang, Zhijun Wang, Zhi-Feng Huang
A computational method is developed for the study of mechanical response and fracture behavior of phase field crystals (PFC), to overcome a limitation of the PFC dynamics which lacks an effective mechanism for describing fast mechanical relaxation of the material system. The method is based on a simple interpolation scheme for PFC (IPFC) making use of a condition of the displacement field to satisfy local elastic equilibration, while preserving key characteristics of the original PFC model. We conduct a systematic study on the mechanical properties of a sample nanoribbon system with honeycomb lattice symmetry subjected to uniaxial tension, for numerical validation of the IPFC scheme and the comparison with the original PFC and modified PFC methods...
January 2019: Physical Review. E
Simas Rackauskas, Tatiana Rackauskas, Andrei Alaferdov, Alfredo Vaz, Raluca Savu, Stanislav A Moshkalev
In this work we propose multilayer graphene (MLG) nanobelts for high current interconnections with single wall carbon nanotubes (SWCNT) and compare with metal contacts. MLG contacts were directly printed on SWCNT, without additional metal parts, demonstrating possibility to use as interconnections in microelectronics. Different work function metals Al, Ti and Pd were probed for the lowest contact resistance with SWCNT. Ti contacts showed best results among the metals owing to its work function closest to SWCNT and therefore giving lowest Schottky barrier...
February 19, 2019: Nanotechnology
Zhi-Wei Huang, Zi-Jie Li, Li-Rong Zheng, Wang-Suo Wu, Zhi-Fang Chai, Wei-Qun Shi
One of the most important reasons for the controversy over the development of nuclear energy is the proper disposal of spent fuel. Separation of actinide and lanthanide ions is an important part of safe long-term storage of radioactive waste. Herein, a three-dimensional (3D) graphene-based macrostructure (GOCS) was utilized to remove actinide thorium and lanthanide europium ions from aqueous solutions. The adsorption of Eu(III) and Th(IV) on the GOCS was evaluated as a function of adsorption time, solution pH, initial ion concentrations, and ionic strength...
February 4, 2019: Environmental Pollution
Jie Xie, Xiang Fang, Xinhua Dai, Bing Shao, Jiancheng Li, You Jiang, Kai Yao, Sihan Wang, Xi Xia, Haiyang Jiang
Pyrenylbutyric acid and streptavidin were coupled to films of reduced graphene oxide (rGO) and then conjugated to a biotinylated broad-spectrum monoclonal antibody against aflatoxins (AFs). It is shown that such films can efficiently and selectively capture AFs inculding AFB1 , AFB2 , AFG1 , AFG2 , AFM1 and AFM2 . The rGO films were characterized by using scanning electron microscopy, energy-dispersive spectroscopy, and raman spectroscopy. The selectivity and purification performance of the antibody-loaded rGO films were investigated...
February 18, 2019: Mikrochimica Acta
Hatice Gamze Soğukömeroğulları, Yaşar Karataş, Metin Celebi, Mehmet Gülcan, Mehmet Sönmez, Mehmet Zahmakiran
We reported the improved catalytic property of Pd (0) nanoparticles decorated on amine-functionalized graphene nanosheets (Pd/GNS-NH2 ) for the hydrogenation of nitrophenol derivatives in the presence of NaBH4 at moderate conditions. Pd/GNS-NH2 nanocatalyst was synthesized by the deposition-reduction method. Sundry techniques such as ICP-OES, P-XRD, XPS, TEM, HR-TEM and EDX have been applied to explain the structure and morphology of the Pd/GNS-NH2 nanocatalyst. The results show that the Pd (0) nanoparticles are perfectly dispersed on the surface of the GNS-NH2 support material (dmean  = 1...
February 10, 2019: Journal of Hazardous Materials
Xifeng Yang, Fangxin Tan, Yaojun Dong, Hailin Yu, Yushen Liu
Based on the non-equilibrium Green function method combined with density functional theory, we investigate the spin-resolved transport through transition metal (TM) (= Cr, Mn, Fe and Ru)-containing molecular devices in the presence of zigzag graphene nanoribbon (ZGNR) electrodes. The wave-function mismatch for the single-spin component results in a perfect spin-filtering property near the Fermi level. Moreover, we also observe Fano and Breit-Wigner resonance peaks in the transmission spectrum. Under a temperature gradient, the single-spin electric current exhibits a remarkable negative differential thermoelectric resistance (NDTR) in the Ru-complex molecular device, which originates from the Fano asymmetry of the single-spin transmission peak near the Fermi level...
February 18, 2019: Physical Chemistry Chemical Physics: PCCP
Hongwu Chen, Wencheng Du, Jing Liu, Liangti Qu, Chun Li
The excellent solution-processability of graphene oxide (GO) has provided a collection of strategies for the construction of functional graphene assemblies. To improve the performance of graphene-based materials, structurally intact GO should be prepared as a precursor for high-quality graphene; however, solution chemical methods have been constantly challenged by a structural integrity versus fabrication yield trade-off. Here, we report a wet chemical method for the high-efficiency production of a high-quality graphene oxide precursor, with all steps conducted at room-temperature...
January 28, 2019: Chemical Science
Akimitsu Narita, Zongping Chen, Qiang Chen, Klaus Müllen
Graphene nanoribbons (GNRs) are quasi-one-dimensional subunits of graphene and have open bandgaps in contrast to the zero-bandgap graphene. The high potential of GNRs as a new family of carbon-based semiconductors, e.g. for nanoelectronic and optoelectronic applications, has boosted the research attempts towards fabrication of GNRs. The predominant top-down methods such as lithographical patterning of graphene and unzipping of carbon nanotubes cannot prevent defect formation. In contrast, bottom-up chemical synthesis, starting from tailor-made molecular precursors, can achieve atomically precise GNRs...
January 28, 2019: Chemical Science
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