Unzipping Carbon Nanotubes at High Impact Ozden, Sehmus; Autreto, Pedro A. S; Tiwary, Chandra Sekhar ...
Nano letters,
07/2014, Letnik:
14, Številka:
7
Journal Article
Recenzirano
The way nanostructures behave and mechanically respond to high impact collision is a topic of intrigue. For anisotropic nanostructures, such as carbon nanotubes, this response will be complicated ...based on the impact geometry. Here we report the result of hypervelocity impact of nanotubes against solid targets and show that impact produces a large number of defects in the nanotubes, as well as rapid atom evaporation, leading to their unzipping along the nanotube axis. Fully atomistic reactive molecular dynamics simulations are used to gain further insights of the pathways and deformation and fracture mechanisms of nanotubes under high energy mechanical impact. Carbon nanotubes have been unzipped into graphene nanoribbons before using chemical treatments but here the instability of nanotubes against defect formation, fracture, and unzipping is revealed purely through mechanical impact.
3D scaffolds of graphene, possessing ultra‐low density, macroporous microstructure, and high yield strength and stiffness can be developed by a novel plasma welding process. The bonding between ...adjacent graphene sheets is investigated by molecular dynamics simulations. The high degree of biocompatibility along with high porosity and good mechanical properties makes graphene an ideal material for use as body implants.
Two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures have been proposed as potential candidates for a variety of applications like quantum computing, neuromorphic computing, ...solar cells, and flexible field effective transistors. The 2D TMDC heterostructures at the present stage face difficulties being implemented in these applications because of lack of large and sharp heterostructure interfaces. Herein, we address this problem via a CVD technique to grow thermodynamically stable heterostructure of 2H/1T′ MoSe2–ReSe2 using conventional transition metal phase diagrams as a reference. We demonstrate how the thermodynamics of mixing in the MoReSe2 system during CVD growth dictates the formation of atomically sharp interfaces between MoSe2 and ReSe2, which can be confirmed by high-resolution scanning transmission electron microscopy imaging, revealing zigzag selenium-terminated interface between the epitaxial 2H and 1T′ lattices. Our work provides useful insights for understanding the stability of 2D heterostructures and interfaces between chemically, structurally, and electronically different phases.
Use of waste polystyrene as an additive in the preparation of biowaste derived char can provide significant new properties that enhance the performance of the epoxy coating on steel surface. This ...work establishes a cost-effective Quasi-graphitic carbon (QGC) derived from the co-pyrolysis of Eucalyptus wood chips and polystyrene as a mix in epoxy (EP) matrix for enhanced the coating properties. The QGC material was characterized by FTIR, XRD, Raman, SEM-EDX, TGA, etc. Results show the incorporation of 0.1 wt.% QGC to the EP matrix enhances corrosion resistance by 98.6 % and boosts mechanical properties with a 245.45 % increase in hardness and a 57.31 % rise in elastic modulus compared to pure EP coatings. Microscopic analysis reveals a smoother, more compact surface with fewer structural defects comapred to pure EP coating. Adhesion tests score the category of 4B, 5B, and water contact angle improve to 102.8°, compared to 61.6° for pure EP coatings. These eco-friendly materials, created through environmentally conscious processes can be a safe alternative to the conventional toxic chemicals used to protect against corrosion,particularly in marine environments.
Transition metal dichalcogenide (TMD) alloys form a broad class of two-dimensional (2D) layered materials with tunable bandgaps leading to interesting optoelectronic applications. In the bottom-up ...approach of building these atomically thin materials, atomic doping plays a crucial role. Here we demonstrate a single step CVD (chemical vapor deposition) growth procedure for obtaining binary alloys and heterostructures by tuning atomic composition. We show that a minute doping of tin during the growth phase of the Mo1–x W x S2 alloy system leads to formation of lateral and vertical heterostructure growth. High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) imaging and density functional theory (DFT) calculations also support the modified stacking and growth mechanism due to the nonisomorphous Sn substitution. Our experiments demonstrate the possibility of growing heterostructures of TMD alloys whose spectral responses can be desirably tuned for various optoelectronic applications.
The development of nanotechnology has been advancing for decades and gained acceleration in the 21st century. Two-dimensional (2D) materials are widely available, giving them a wide range of material ...platforms for technological study and the advancement of atomic-level applications. The design and application of 2D materials are discussed in this review. In order to evaluate the performance of 2D materials, which might lead to greater applications benefiting the electrical and electronics sectors as well as society, the future paradigm of 2D materials needs to be visualized. The development of 2D hybrid materials with better characteristics that will help industry and society at large is anticipated to result from intensive research in 2D materials. This enhanced evaluation might open new opportunities for the synthesis of 2D materials and the creation of devices that are more effective than traditional ones in various sectors of application.
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Materials science; Nanomaterials; Materials application
The present investigation reports the preparation of freestanding nanocrystalline Zn by combined mechanical milling at cryogenic and room temperatures. The cryomilling is used as an effective means ...of rapid fracturing. The detailed scanning electron microscopy and transmission electron microscopy observations indicate that the minimum crystallite size is 6 ± 2 nm after 3 hours of cryomilling. The crystallite size increases to 30 ± 2 nm after 3 hours of room temperature milling of the cryomilled powder due to deformation-induced sintering. Detailed theoretical analysis allows us to obtain a diagram of size of the nanoparticles formed
vs
temperature to explain the experimental findings.
Luminescent downshifting (LDS) materials are in great demand for their applications in light conversion devices. In this work, by an ingenious chemical approach of in situ doping, N-doped graphene ...quantum dots (N-GQDs) have been synthesized with tailored green photoluminescence (PL) under ultraviolet (UV) light excitation. The incorporation of N atoms in the form of pyridinic and graphitic C–N bonding into the sp2-hybridized graphitic framework of N-GQDs has led to tailored LDS via PL emissions. The LDS property of synthesized N-GQDs has been advantageously utilized to demonstrate enhanced responsivity (R) of a low-cost commercially available photoconductive cell (PC) for detection of UVA radiation through an indigenous technique. The linear optical responses of samples are optimized by varying the concentration and the dispersing medium. Also the N-GQDs are shown to be photostable in poly(vinyl alcohol) (PVA) hydrogel. A 60% enhancement in photocurrent of the PC-based photodetector under UV radiation has been obtained here by using N-GQDs/PVA as LDS material. Thus, detection of UVA radiation with a high specific detectivity (D*) of 9 × 1013 Jones and responsivity (R) of 3 A W–1 has been demonstrated, which might open the opportunity of using this material in future energy conversion devices.
In this study, Green graphene (GG) was synthesized from residual agricultural biomass through pyrolysis and prepared various sizes (2D, 37 μm, 45 μm, 53 μm, and 100 μm) via mechanical and liquid ...phase exfoliation. These GG samples were incorporated into an EP matrix, forming GG/EP composite coatings for carbon steel. Corrosion resistance was assessed via PDP and EIS techniques. The 37 μm-GG/EP composite coating also showed uniform distribution and compact surfaces. The 37 μm-GG/EP composite coating displayed higher corrosion inhibition (99 %) owing to the even distribution of GG within the EP matrix than the uncoated, along with enhanced hydrophobicity, tensile strength (61.3 %), fracture strain (77.2 %), and toughness (90.5 %) than pure EP coating. Improved corrosion resistance, which was found related to three main factors: first, GGs enhance the coating integrity by obstructing pores and flaws, to stop corrosive media from penetrating. Second, the well-dispersed GG sheet lengthens the diffusion pathways for corrosive agents to the carbon steel substrate, consequently lenghtening the corrosion process. Third, at 37 μm size the resititve forcefields of the GG/EP structure become the most effecitve agaisnt the corrosive media. The study also establishes GG as an eco-friendly sustainable alternative of non-renewable resource based mined compounds of Zn, etc. that are universally and traditionally used, for protective coatings.
•To prevent corrosion, a range of different-sized green graphene pieces were produced and individually added to an EP matrix.•Anticorrosion performance of various GG/EP composite coatings on carbon steel in 3.5 wt.% NaCl solution was examined.•37 μm-GG/EP composite coating enhances hydrophobicity, anticorrosion and mechanical properties.•37 μm-GG/EP composite coating shows better barrier protection w.r.t. conventional coating.•A scalable, eco-friendly anticorrosive coating has been developed.
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