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Functionalization of graphene

Chun-Ying Huang, Chun-Chieh Kang, Yu-Chi Ma, Yu-Cheng Chou, Jian-Huei Ye, Ru-Ting Huang, Chen-Zih Siao, Yu-Ching Lin, Yu-Hao Chang, Ji-Lin Shen, Tai-Yuan Lin
ZnO-based heterojunctions have found applications as self-powered ultraviolet photodetectors (PDs). However, high doping levels are not compatible with high mobility for metallic doped ZnO-based PDs so further development has been inhibited. This study demonstrates a method to increase the open-circuit voltage (Voc) that allows keeping a sufficiently high level of mobility of ZnO, using a ZnO nanorod/GaN heterojunction that incorporates graphene nanosheets as the active layer. These hybrid PDs have triple the value for Voc of PDs that have only pure ZnO and better exhibit photo-response characteristics...
August 16, 2018: Nanotechnology
Joseph L Garrett, Marina S Leite, Jeremy N Munday
The spatial resolution of atomic force microscopy (AFM) needed to resolve material interfaces is limited by the tip-sample separation ( d) dependence of the force used to record an image. Here, we present a new multiscale functional imaging technique that allows for in situ tunable spatial resolution, which can be applied to a wide range of inhomogeneous materials, devices, and interfaces. Our approach uses a multifrequency method to generate a signal whose d-dependence is controlled by mixing harmonics of the cantilever's oscillation with a modulated force...
August 16, 2018: ACS Applied Materials & Interfaces
Jiaying Wang, Stefan Wagner, Wenjun Chen, Yuesong Shi, Abdoulaye Ndao, Leon Li, Boubacar Kante, Donald J Sirbuly, Max C Lemme, Oscar Vazquez Mena
A novel layer-by-layer 3D architecture allowing to expand device fabrication in the vertical direction and integrating functional nanomaterials is presented by emulating civil engineering. The architecture uses SU-8 pillars as structural columns which supports multiple horizontal suspended thin films. The films then serves as platforms for the integration of nanomaterials and nano devices. Multiple graphene layers suspended across SU-8 pillars with precise control on their vertical spacing are demonstrated...
August 16, 2018: ACS Applied Materials & Interfaces
Xuelei Su, Zhijie Xue, Gang Li, Ping Yu
Zigzag edges of graphene nanoribbons, which are predicted to host spin-polarized electronic states, hold great promise for future spintronic device applications. The ability to precisely engineer the zigzag edge state is of crucial importance for realizing its full potential functionalities in nanotechnology. By combining scanning tunneling microscopy and atomic force microscopy, we demonstrate the zigzag edge states have energy splitting upon fusing manganese the phthalocyanine molecule with the short armchair graphene nanoribbon termini...
August 17, 2018: Nano Letters
Qing Li, Haiping Lin, Ruitao Lv, Mauricio Terrones, Lifeng Chi, Werner Hofer, Minghu Pan
Pristine graphene is known to be non-magnetic due to its π-conjugated electron system. However, we find that localized magnetic moments can be generated by chemically attaching boron atoms to the graphene sheets. Such spin-polarized states are evidenced by the spin-split of the density of states (DOS) peaks near the Fermi level in scanning tunneling spectroscopy (STS). In the vicinity of several co-adsorbed boron atoms, the Coulomb repulsion between multiple spins leads to antiferromagnetic coupling for the propagating spin states in the graphene lattice, manifesting itself as an increment of spin-down state at specific regions...
August 16, 2018: Nano Letters
M N Najafi, N Ahadpour, J Cheraghalizadeh, H Dashti-Naserabadi
The statistical properties of the carrier density profile of graphene in the ground state in the presence of particle-particle interaction and random charged impurity in zero gate voltage has been recently obtained by Najafi et al. [Phys. Rev. E 95, 032112 (2017)2470-004510.1103/PhysRevE.95.032112]. The nonzero chemical potential (μ) in gated graphene has nontrivial effects on electron-hole puddles, since it generates mass in the Dirac action and destroys the scaling behaviors of the effective Thomas-Fermi-Dirac theory...
July 2018: Physical Review. E
Vivekanand Shukla, Rafael B Araujo, Naresh K Jena, Rajeev Ahuja
Graphene's emergence can be viewed as a positive upheaval in 2D materials research. Along the same line, the realization of a related elemental 2D material, borophene, is another breakthrough. To circumvent the stability issues of borophene, which is reported to have been synthesized on metallic substrates under extreme conditions, hydrogenation of borophene (otherwise called as borophane or hydrogen boride or boron hydride) has been a plausible solution, but only proposed computationally. A recent report (H...
August 15, 2018: Physical Chemistry Chemical Physics: PCCP
Bagher Eftekhari-Sis, Zahra Rezazadeh, Ali Akbari, Mojtaba Amini
A nanosensor, based on 8-hydroxyquinoline functionalized graphene oxide, was developed for the fluorescence detection of Zn2+ . It showed high selectivity and sensitivity for Zn2+ ion in aqueous solution over other metal ions such as Li+ , Na+ , Ca2+ , Mg2+ , Al3+ , Cd2+ , Co2+ , Cu2+ , Hg2+ , Ni2+ , Pb2+ , Fe2+ , Fe3+ and Cr3+ . Due to the linearity of the emission intensity toward Zn2+ concentration, fluorescent technique could be used for the detection of Zn2+ ion even at very low concentrations.
August 14, 2018: Journal of Fluorescence
Yang Yu, Lihe Yan, Mengmeng Yue, Huanhuan Xu
Reduced graphene oxide (rGO) functionalized with silver nanoparticles (Ag NPs) is prepared using a femtosecond laser ablation in liquids method. By ablating the mixed aqueous solutions of silver nitrate and graphene oxide (GO) using femtosecond laser pulses, Ag ions and GO are simultaneously reduced and well-dispersed Ag NPs supported on rGO are obtained. The effect of laser power, irritation time and Ag ion concentration on the optical property and morphology of the products are systematically studied. The nonlinear optical responses of the functionalized graphene are studied using a nanosecond Z-scan technique...
July 2018: Royal Society Open Science
C-Yoon Kim, William K A Sikkema, Jin Kim, Jeong Ah Kim, James Walter, Raymond Dieter, Hyung-Min Chung, Andrea Mana, James M Tour, Sergio Canavero
A sharply transected spinal cord has been shown to be fused under the accelerating influence of membrane fusogens such as polyethylene glycol (PEG) (GEMINI protocol). Previous work provided evidence that this is in fact possible. Other fusogens might improve current results. In this study, we aimed to assess the effects of PEGylated graphene nanoribons (PEG-GNR, and called "TexasPEG" when prepared as 1wt% dispersion in PEG600) versus placebo (saline) on locomotor function recovery and cellular level in a rat model of spinal cord transection at lumbar segment 1 (L1 ) level...
August 2018: Neural Regeneration Research
Peter Schweizer, Christian Dolle, Erdmann Spiecker
Topological defects in crystalline solids are of fundamental interest in physics and materials science because they can radically alter the properties of virtually any material. Of particular importance are line defects, known as dislocations, which are the main carriers of plasticity and have a tremendous effect on electronic and optical properties. Understanding and controlling the occurrence and behavior of those defects have been of major and ongoing interest since their discovery in the 1930s. This interest was renewed with the advent of two-dimensional materials in which a single topological defect can alter the functionality of the whole system and even create new physical phenomena...
August 2018: Science Advances
Pranay Ranjan, Shweta Agrawal, Apurva Sinha, T Rajagopala Rao, Jayakumar Balakrishnan, Ajay D Thakur
A low cost, non-explosive process for the synthesis of graphene oxide (GO) is demonstrated. Using suitable choice of reaction parameters including temperature and time, this recipe does not require expensive membranes for filtration of carbonaceous and metallic residues. A pre-cooling protocol is introduced to control the explosive nature of the highly exothermic reactions during the oxidation process. This alleviates the requirement for expensive membranes and completely eliminates the explosive nature of intermediate reaction steps when compared to existing methods...
August 13, 2018: Scientific Reports
Sihyun Sung, Chaoxing Wu, Hyun Soo Jung, Tae Whan Kim
One diode and one resistor (1D-1R) memristive devices based on inorganic Schottky diodes and poly(methylsilsesquioxane) (PMSSQ):graphene quantum dot (GQD) hybrid nanocomposites were fabricated to achieve stable memory characteristics. Current-voltage (I-V) curves for the Al/PMSSQ:GQDs/Al/p-Si/Al devices at room temperature exhibited write-once, read-many-times memory (WORM) characteristics with an ON/OFF ratio of as large as 104 resulting from the formation of a 1D-1R structure. I-V characteristics of the WORM 1D-1R device demonstrated that the memory and the diode behaviors of the 1D-1R device functioned simultaneously...
August 13, 2018: Scientific Reports
Feiyan Liu, Dan Yang, Yawen Liu, Qianqian Cao, Yulian Sun, Qiong Wang, Hao Tang
The surface functional groups of GO have significant effects on the performances of GO-based gene delivery vector. In this work, the polyamidoamine (PAMAM) dendrimer and glycyrrhetinic acid (GA) were tethered onto the GO surface by one-step covalently cross-linking method. The micro-morphology, surface functional groups, and zeta potential of the obtained GO-PAMAM-GA hybrid were characterized and verified. The effects of GA amount in the hybrid on the dispersive property in cell culture medium, in vitro cytotoxicity to human hepatocarcinoma (SMMC-7721) and human embryonic kidney (HEK-293) cells, and gene (plasmid DNA of enhanced green fluorescent protein) transfection capacity were investigated in detail...
July 30, 2018: Colloids and Surfaces. B, Biointerfaces
Xin Wu, Hui Li, Ning Xiao
Medication obstruction of microscopic organisms has turned into a worldwide medical issue, as it makes the ordinary anti-toxins less effective. It is desperately expected to investigate novel antibacterial materials and create viable treatment techniques to defeat the medication obstruction of anti-infection agents. Herein, we effectively fabricated silver nanoparticles improved proline/graphene oxide nano-flakes (GO-Pro/n-Ag) as novel anti-pathogenic substance through simplistic technique. The property of the silver nanoparticles activated discharge gave amazing antibacterial and antifungal movement against the pathogenic microorganism...
July 18, 2018: Journal of Photochemistry and Photobiology. B, Biology
Siyong Gu, Chien-Te Hsieh, Tzu-Wei Lin, Chun-Yao Yuan, Yasser Ashraf Gandomi, Jeng-Kuei Chang, Jianlin Li
Graphene sheets that can exhibit electrical conducting and semiconducting properties are highly desirable and have potential applications in fiber communications, photodetectors, solar cells, semiconductors, and broadband modulators. However, there is currently no efficient method that is able to tune the band gap of graphene sheets. This work adopts an efficient atomic layer oxidation (ALO) technique to cyclically increase the oxidation level of graphene sheets, thus, tuning their electrical conductance, band-gap structure, and photoluminescence (PL) response...
August 13, 2018: Nanoscale
Jia Lin Zhang, Cheng Han, Zehua Hu, Li Wang, Lei Liu, Andrew T S Wee, Wei Chen
Black phosphorus (BP), first synthesized in 1914 and rediscovered as a new member of the family of 2D materials in 2014, combines many extraordinary properties of graphene and transition-metal dichalcogenides, such as high charge-carrier mobility, and a tunable direct bandgap. In addition, it displays other distinguishing properties, e.g., ambipolar transport and highly anisotropic properties. The successful application of BP in electronic and optoelectronic devices has stimulated significant research interest in other allotropes and alloys of 2D phosphorene, a class of 2D materials consisting of elemental phosphorus...
August 13, 2018: Advanced Materials
A R Rafieerad, A R Bushroa, Ahmad Amiri, K Kalaiselvam, K M Vellasamy, J Vadivelu
Antibacterial ability is vital in biological approaches as well as functional biomaterials. Besides, cytocompatibility aspect of biologic media, tissue and organs is always concern for appropriate synthesis. From the past, metallic/oxide phases of silver (Ag) material in various macro, micro or nano configurations have been widely used for antibacterial targets. While, background of Ag toxicity within particle, film and composites is posing gradual ion release affected by molecular bounding. Recent researches conducted to control, optimize and neutralize Ag limitations finding the benefits of ideal (∼ 100%) mediation against both Gram-negative and Gram-positive bacteria...
July 31, 2018: Journal of Hazardous Materials
Wenwen Fang, Nonappa, Marika Vitikainen, Pezhman Mohammadi, Salla Koskela, Miika Soikkeli, Ann Westerholm-Parvinen, Christopher P Landowski, Merja Penttilä, Markus B Linder, Päivi Laaksonen
Liquid-liquid phase transition known as coacervation of resilin-like-peptide fusion proteins containing different terminal domains were investigated. Two different modular proteins were designed and produced and their behavior were compared to a resilin-like-peptide without terminal domains. The size of the particle-like coacervates was modulated by the protein concentration, pH and temperature. The morphology and three-dimensional (3D) structural details of the coacervate particles were investigated by cryogenic transmission electron microscopy (cryo-TEM) and tomography (cryo-ET) reconstruction...
July 24, 2018: Colloids and Surfaces. B, Biointerfaces
Piyaluk Nurerk, Warapon Bunkoed, Proespichaya Kanatharana, Opas Bunkoed
A calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate adsorbent was fabricated for the preconcentration of aflatoxins. The highly porous developed adsorbent does not produce the high back pressure that normally occurs in particles packed cartridges and its large surface area helps to improve adsorption. The highly efficient adsorption of aflatoxins by the hybrid adsorbent is facilitated via hydrogen bonding and hydrophobic and π-π interactions. Polymerization time, amount of calix[4]arene-functionalized graphene oxide, type and volume of desorption solvent, sample pH, sample volume and sample flow rate were optimized...
August 10, 2018: Journal of Separation Science
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