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Yurii Stubrov, Andrii Nikolenko, Viktor Strelchuk, Sergii Nedilko, Vitalii Chornii
Confocal micro-Raman spectroscopy is used as a sensitive tool to study the nature of laser-induced defects in single-layer graphene. Appearance and drastic intensity increase of D- and D' modes in the Raman spectra at high power of laser irradiation is related to generation of structural defects. Time- and power-dependent evolution of Raman spectra is studied. The dependence of relative intensity of defective D- and D' bands is analyzed to relate the certain types of structural defects. The surface density of structural defects is estimated from the intensity ratio of D- and G bands using the D-band activation model...
December 2017: Nanoscale Research Letters
Xiaohu Luo, Song Yuan, Xinyu Pan, Caixia Zhang, Shuo Du, Yali Liu
Effective prevention of the water, oxygen, and chloride ions held in the hydrotalcite interlayer from diffusing through the layered double hydroxides ( LDH ) layer is crucial importance for its further practical application in the corrosion protection. In this study, a hybrid reduced graphene oxide ( RGO ) nanosheet /Zn2+/Al3+ layered double hydroxides ( RGO/ZnAl-LDH ) composite film with an excellent corrosion protection property on the 6N01 aluminum alloy surface was synthesized by a newly and facile hydrothermal continuous flow method,which can enable direct growth on the substrate...
April 26, 2017: ACS Applied Materials & Interfaces
Leyla Saeednia, Li Yao, Marcus Berndt, Kim Cluff, Ramazan Asmatulu
Chitosan has the ability to make injectable thermosensitive hydrogels which has been highly investigated for drug delivery applications. The addition of nanoparticles is one way to increase the mechanical strength of thermosensitive chitosan hydrogel and subsequently and control the burst release of drug. Graphene nanoparticles have shown unique mechanical, optical and electrical properties which can be exploited for biomedical applications, especially in drug delivery. This study, have focused on the mechanical properties of a thermosensitive and injectable hybrid chitosan hydrogel incorporated with graphene nanoparticles...
April 26, 2017: Journal of Biomedical Materials Research. Part A
Michelle C Sherrott, Philip W C Hon, Katherine T Fountaine, Juan C Garcia, Samuel M Ponti, Victor Watson Brar, Luke A Sweatlock, Harry A Atwater
Metasurfaces offer significant potential to control far-field light propagation through the engineering of amplitude, polarization, and phase at an interface. We report here phase modulation of an electronically reconfigurable metasurface and demonstrate its utility for mid-infrared beam steering. Using a gate-tunable graphene-gold resonator geometry, we demonstrate highly tunable reflected phase at multiple wavelengths and show up to 237° phase modulation range at an operating wavelength of 8.50 μm. We observe a smooth monotonic modulation of phase with applied voltage from 0° to 206° at a wavelength of 8...
April 26, 2017: Nano Letters
Yo-Han Kim, Eun Yeol Lee, Hyun Ho Lee, Tae Seok Seo
Reduced graphene oxide quantum dot (rGOQD) devices in formats of capacitor and thin film transistor (TFT) were demonstrated and examined as the first trial to achieve non-ambipolar channel property. In addition, through gold nanoparticles (Au NPs) layer embedded between the rGOQD active channel and dielectric layer, memory capacitor and TFT performances were realized by capacitance-voltage (C-V) hysteresis and gate program, erase, and reprogram biases. First, capacitor structure of the rGOQD memory device was constructed to examine memory charging effect featured in hysteretic C-V behavior with a 30 nm dielectric layer of crosslinked polyvinyl alcohol (PVA)...
April 26, 2017: ACS Applied Materials & Interfaces
Nifang Zhao, Miao Yang, Qian Zhao, Weiwei Gao, Tao Xie, Hao Bai
Through designing hierarchical structures, particularly optimizing the chemical and architectural interactions at its inorganic/organic interface, nacre has achieved an excellent combination of contradictory mechanical properties such as strength and toughness, which is highly demanded yet difficult to achieve by most synthetic materials. Most techniques applied to develop nacre-mimetic composites have been focused on mimicking the 'brick-and-mortar' structure, but the interfacial architectural features, especially the asperities and mineral bridges of 'bricks', have been rarely concerned, which are of equal importance for enhancing mechanical properties of nacre...
April 26, 2017: ACS Nano
Hucheng Zhang, Yingying Shang, Jing Zhao, Jianji Wang
This work developed a facile colloidal route to synthesize BH4--capped PdxAgy nanoparticles (NPs) in water using the reducing ionic liquids of [Cnmim]BH4, and the resulting NPs were prone to form the nanocomposites with [amim]+-modified reduced graphene (RG). The removal of the metal-free inorganic ions of BH4- can create the profoundly exposed interfaces on the PdxAgy NPs during the electrooxidation, and favor the ethanol oxidation reaction (EOR) in lowering energy barrier. The counterions of [Cnmim]+ can gather ethanol, OH- ions, and the reaction intermediates on catalysts, and synergistically interact with RG to facilitate the charge transfer in nanocomposites...
April 26, 2017: ACS Applied Materials & Interfaces
Boyang Mao, David González Calatayud, Vincenzo Mirabello, Haobo Ge, Benjamin J Hodges, Robert M J Jacobs, Ashley M Shepherd, José Alberto Ribeiro Martins, Navaratnarajah Kuganathan, Jorge Bernardino De La Serna, Stanley W Botchway, Sofia Ioana Pascu
Two new routes to functionalized SWNTs have been established using a bulky Zn(II)-porphyrin featuring thiolate groups at the periphery. We probed the optical properties of this Zinc(II)-substituted, bulky aryl porphyrin and those of the corresponding new nano-composites with single walled carbon nanotube (SWNTs) and coronene, as a model for graphene. We report hereby on: (i) the supramolecular interactions between the pristine SWNTs and Zn(II)-porphyrin by virtue of π-π stacking, and (ii) a novel covalent binding strategy based on the Bingel reaction...
April 25, 2017: Chemistry: a European Journal
Filiberto Ricciardella, Sten Vollebregt, Tiziana Polichetti, Mario Miscuglio, Brigida Alfano, Maria L Miglietta, Ettore Massera, Girolamo Di Francia, Pasqualina M Sarro
The crystal structure of graphene flakes is expected to significantly affect their sensing properties. Here we report an experimental investigation on the crystalline structure of graphene aimed at exploring the effects on the gas sensing properties. The morphology of graphene, prepared via Chemical Vapor Deposition (CVD), Liquid Phase Exfoliation (LPE) and Mechanical Exfoliation (ME), is inspected through Raman spectroscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). CVD and LPE-graphene structures are found to be more defective with respect to ME-graphene...
April 26, 2017: Nanoscale
Jun Shen, Xiangzhi Liu, Xuefen Song, Xinming Li, Jun Wang, Quan Zhou, Shi Luo, Wenlin Feng, Xingzhan Wei, Shirong Lu, Shuanglong Feng, Chunlei Du, Yuefeng Wang, Haofei Shi, Dapeng Wei
Schottky heterojunctions based on graphene-silicon structures are promising for high-performance photodetectors. However, existing fabrication processes adopt transferred graphene as electrodes, limiting process compatibility and generating pollution because of the metal catalyst. In this report, photodetectors are fabricated using directly grown graphene nanowalls (GNWs) as electrodes. Due to the metal-free growth process, GNWs-Si heterojunctions with an ultralow measured current noise of 3.1 fA Hz(-1/2) are obtained, and the as-prepared photodetectors demonstrate specific detectivities of 5...
April 26, 2017: Nanoscale
Nicolas Leconte, Hakseong Kim, Ho-Jong Kim, Dong Han Ha, Kenji Watanabe, Takashi Taniguchi, Jeil Jung, Suyong Jung
Graphene bubbles are often formed when graphene and other layered two-dimensional materials are vertically stacked as van der Waals heterostructures. Here, we investigate how graphene bubbles and their related disorder impact the quantum transport behavior of graphene in the absence and presence of external magnetic fields. By combining experimental observations and numerical simulations, we find that the disorder induced by the graphene bubbles is mainly from p-type dopants and the charge transport in pristine graphene can be severely influenced by the presence of bubbles via long- and short-range scattering even with a small bubble-coverage of 2% and below...
April 26, 2017: Nanoscale
Sung-Soo Kim, Donghwi Kang, Byeong-Hyeok Sohn
We report the synthesis of arrayed nanorings with tunable physical dimensions from thin films of polystyrene-<i>block</i>-poly(4-vinylpyridine) (PS-P4VP) micelles. For accurate control of the inner and outer diameters of the nanorings, we added imidazolium-based ionic liquids (ILs) into the micellar solution, which were eventually incorporated into the micellar cores. We observed the structural changes of the micellar cores coated on a substrate due to the presence of ILs. The spin-coated micellar cores were treated with an acidic precursor solution and generated toroid nanostructures, of which size depended on the amount of IL loaded into the micelles...
April 26, 2017: Nanotechnology
Naresh K Jena, Rafael B Araujo, Vivekanand Shukla, Rajeev Ahuja
Borophene, single atomic-layer sheet of boron (Science, 2015, 350, 1513), is a rather new entrant into the burgeoning class of 2D materials. Borophene exhibits anisotropic metallic properties whereas its hydrogenated counterpart borophane is reported to be a gapless Dirac material lying on the same bench with the celebrated graphene. Interestingly, this transition of borophane also rendered stability to it considering the fact that borophene was synthesized under ultra-high vacuum conditions on a metallic (Ag) substrate...
April 26, 2017: ACS Applied Materials & Interfaces
Shahid Sattar, Udo Schwingenschlögl
In this article, we study the electronic properties of graphene in contact with monolayer and bilayer PtSe2 using first-principles calculations. It turns out that there is no charge transfer between the components because of the weak van der Waals interaction. We calculate the work functions of monolayer and bilayer PtSe2 and analyze the band bending at the contact with graphene. The formation of an n-type Schottky contact with monolayer PtSe2 and a p-type Schottky contact with bilayer PtSe2 is demonstrated...
April 26, 2017: ACS Applied Materials & Interfaces
Lele Peng, Pan Xiong, Lu Ma, Yifei Yuan, Yue Zhu, Dahong Chen, Xiangyi Luo, Jun Lu, Khalil Amine, Guihua Yu
Transition metal oxide nanomaterials are promising electrodes for alkali-ion batteries owing to their distinct reaction mechanism, abundant active sites and shortened ion diffusion distance. However, detailed conversion reaction processes in terms of the oxidation state evolution and chemical/mechanical stability of the electrodes are still poorly understood. Herein we explore a general synthetic strategy for versatile synthesis of various holey transition metal oxide nanosheets with adjustable hole sizes that enable greatly enhanced alkali-ion storage properties...
April 26, 2017: Nature Communications
Junga Ryou, Jinwoo Park, Gunn Kim, Suklyun Hong
Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled (5,6)-AGNRs) are metallic, the edge-functionalized (5,6)-AGNRs with substitutional atoms (i.e., nitrogen, oxygen, sulfur, and selenium) opens a band gap, similarly to the defect-free AGNRs. Furthermore, we find that electronic band structures and charge densities vary, depending on the wave vector: The band structures of edge-functionalized (5,6)-N-AGNRs by substitution resemble those of defect-free (N-1)-AGNR at the Γ point, while those at the X point show the original ones of the defect-free N-AGNR...
April 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yibai Sun, Wanlin Fu, Yunqian Dai, Yiyang Huang, Jie Zhou, Chengqian Huang, Chongya Yang, Meiyou Huang, Rongwei Ma, Baoping Lin
Graphene sheets, a flexible two-dimensional material with excellent absorptive capacity, have great potential as absorbing materials. However, it has always been suffering from irreversible aggregation and thus lose the abundant active sites and large surface area. In this paper, large-scale graphene oxide (GO) sheets were cut and reduced into tiny reduced graphene oxide (RGO) sheets by a cell-break sonicator, for producing numerous defects which is the center of chemisorption. Furthermore, sodium titanate nanowires functioned as a framework help to disperse tiny RGO sheets uniformly...
April 26, 2017: Nanotechnology
Manish Kumar Pal, Shyam Pyari Jaiswar, Ashish Dwivedi, Shruti Goyal, Vinay Nand Dwivedi, Anumesh Kumar Pathak, Vinod Kumar, Pushp Lata Sankhwar, Ratan Singh Ray
Ovarian cancer is most lethal among all gynecologic malignancies. Paclitaxel (PTX) is well used chemotherapeutic regimen for cancer control; however its undesired toxicity has been always a matter of concern for clinicians. Here we used the graphene oxide coated nanotised apigenin (GO-NA) as chemo sensitizing agent to enhance the efficacy of paclitaxel to overcome the limitations of chemotherapy. GO and GO-Apigenin was prepared by modified Hummers method and the nanoparticles were characterized by dynamic light scattering and transmission electron microscopy Human ovarian adenocarcinomas (SKOV-3) cells was treated by DMSO, Group I (Control)-McCoy's 5A Medium, Group II-Paclitaxel (5nM) alone, Group III- Nanotised Apigenin (GO-NA-10μM) Group IV- Paclitaxel (5nM) + GO-NA (10μM)...
April 24, 2017: Anti-cancer Agents in Medicinal Chemistry
Massimiliano Papi, Valentina Palmieri, Francesca Bugli, Marco De Spirito, Maurizio Sanguinetti, Carlotta Ciancico, Maria Chiara Braidotti, Silvia Gentilini, Luca Angelani, Claudio Conti
Antibacterial surfaces have an enormous economic and social impact on the worldwide technological fight against diseases. However, bacteria develop resistance and coatings are often not uniform and not stable in time. The challenge is finding an antibacterial coating that is biocompatible, cost-effective, not toxic, and spreadable over large and irregular surfaces. Here we demonstrate an antibacterial cloak by laser printing of graphene oxide hydrogels mimicking the Cancer Pagurus carapace. We observe up to 90% reduction of bacteria cells...
December 5, 2016: Scientific Reports
Pichamon Sirisinudomkit, Pawin Iamprasertkun, Atiweena Krittayavathananon, Tanut Pettong, Peerapan Dittanet, Montree Sawangphruk
Although Nickel-Cadmium (NiCd) and Nickel-metal hydride (NiMH) batteries have been widely used, their drawbacks including toxic Cd and expensive La alloy at the negative electrodes, low energy density (40-60 Wh/kg for NiCd and 140-300 Wh/L for NiMH), low power density (150 W/kg for NiCd and 1000 W/kg for NiMH), and low working potential (1.2 V) limit their applications. In this work, Cd and La alloy were replaced with N-doped reduced graphene oxide aerogel (N-rGOae) providing a hybrid energy storage (HES) having the battery and supercapacitor effects...
April 25, 2017: Scientific Reports
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