15 research outputs found
Growth of carbon nanotubes on quasicrystalline alloys
We report on the synthesis of carbon nanotubes on quasicrystalline alloys.
Aligned multiwalled carbon nanotubes (MWNTs) on the conducting faces of
decagonal quasicrystals were synthesized using floating catalyst chemical vapor
deposition. The alignment of the nanotubes was found perpendicular to the
decagonal faces of the quasicrystals. A comparison between the growth and tube
quality has also been made between tubes grown on various quasicrystalline and
SiO2 substrates. While a significant MWNT growth was observed on decagonal
quasicrystalline substrate, there was no significant growth observed on
icosahedral quasicrystalline substrate. Raman spectroscopy and high resolution
transmission electron microscopy (HRTEM) results show high crystalline nature
of the nanotubes. Presence of continuous iron filled core in the nanotubes
grown on these substrates was also observed, which is typically not seen in
MWNTs grown using similar process on silicon and/or silicon dioxide substrates.
The study has important implications for understanding the growth mechanism of
MWNTs on conducting substrates which have potential applications as heat sinks
Aligned multi-walled carbon nanotube-embodied hydrogel via low magnetic field: A strategy for engineering aligned injectable scaffolds
Injectable scaffolds are a promising strategy to restore and regenerate damaged and diseased tissues. They require minimally invasive procedure and allow the formation of an in-situ structure of any shape. However, the formation of 3D in-situ structure with aligned morphologies using a method which could be easily transferred to clinical settings remains a challenge. Herein, the rational design of an aligned injectable hydrogel-based scaffold via remote-induced alignment is reported. Carboxylated multi-walled carbon nanotubes (cMWCNT) are aligned into hydrogel via low magnetic field. The uniform dispersion and alignment of cMWCNT into the hydrogel are clearly demonstrated by small angle neutron scattering. The obtained aligned cMWCNT-embodied hydrogel is stable over 7 days at room temperature and as well at body temperature (i.e. 37 °C). As unique approach, the formation of MWCNT-hydrogel composite is investigated combining rheology with molecular dynamic and quantum mechanical calculations. The increase of MWCNT concentration into the hydrogel decreases the total energy promoting structural stabilization and increase of stiffness. The remote aligning of injectable hydrogel-based scaffold opens up horizons in the engineering of functional tissues which requires specific cell orientation.publishedVersio
Aligned multi-walled carbon nanotube-embodied hydrogel via low magnetic field : A strategy for engineering aligned injectable scaffolds
Injectable scaffolds are a promising strategy to restore and regenerate damaged and diseased tissues. They require minimally invasive procedure and allow the formation of an in-situ structure of any shape. However, the formation of 3D in-situ structure with aligned morphologies using a method which could be easily transferred to clinical settings remains a challenge. Herein, the rational design of an aligned injectable hydrogel-based scaffold via remote-induced alignment is reported. Carboxylated multi-walled carbon nanotubes (cMWCNT) are aligned into hydrogel via low magnetic field. The uniform dispersion and alignment of cMWCNT into the hydrogel are clearly demonstrated by small angle neutron scattering. The obtained aligned cMWCNT-embodied hydrogel is stable over 7 days at room temperature and as well at body temperature (i.e. 37 °C). As unique approach, the formation of MWCNT-hydrogel composite is investigated combining rheology with molecular dynamic and quantum mechanical calculations. The increase of MWCNT concentration into the hydrogel decreases the total energy promoting structural stabilization and increase of stiffness. The remote aligning of injectable hydrogel-based scaffold opens up horizons in the engineering of functional tissues which requires specific cell orientation.publishedVersionPeer reviewe
2D tungsten chalcogenides:synthesis, properties and applications
Abstract
Layered transition metal chalcogenides possess properties that not only open up broad fundamental scientific enquiries but also indicate that a myriad of applications can be developed by using these materials. This is also true for tungsten‐based chalcogenides which can provide an assortment of structural forms with different electronic flairs as well as chemical activity. Such emergence of tungsten based chalcogenides as advanced forms of materials lead several investigators to believe that a tremendous opportunity lies in understanding their fundamental properties, and by utilizing that knowledge the authors may create function specific materials through structural tailoring, defect engineering, chemical modifications as well as by combining them with other layered materials with complementary functionalities. Indeed several current scientific endeavors have indicated that an incredible potential for developing these materials for future applications development in key technology sectors such as energy, electronics, sensors, and catalysis are perhaps viable. This review article is an attempt to capture this essence by providing a summary of key scientific investigations related to various aspects of synthesis, characterization, modifications, and high value applications. Finally, some open questions and a discussion on imminent research needs and directions in developing tungsten based chalcogenide materials for future applications are presented
High photoresponse of individual WS<sub>2</sub> nanowire-nanoflake hybrid materials
van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS2 nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to ∼0.4 AW−1 are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices
Viable route towards large-area 2D MoS₂ using magnetron sputtering
Abstract
Structural, interfacial, optical, and transport properties of large-area MoS₂ ultra-thin films on BN-buffered silicon substrates fabricated using magnetron sputtering are investigated. A relatively simple growth strategy is demonstrated here that simultaneously promotes superior interfacial and bulk MoS₂ properties. Few layers of MoS₂ are established using x-ray reflectivity, diffraction, ellipsometry, and Raman spectroscopy measurements. Layer-specific modeling of optical constants show very good agreement with first-principles calculations. Conductivity measurements reveal that few-layer MoS₂ films are more conducting than many-layer films. Photo-conductivity measurements reveal that the sputter deposited MoS₂ films compare favorably with other large-area methods. Our work illustrates that sputtering is a viable route for large-area device applications using transition metal dichalcogenides
Aligned carbon nanotube/zinc oxide nanowire hybrids as high performance electrodes for supercapacitor applications
Abstract
Carbon nanotube/metal oxide based hybrids are envisioned as high performance electrochemical energy storage electrodes since these systems can provide improved performances utilizing an electric double layer coupled with fast faradaic pseudocapacitive charge storage mechanisms. In this work, we show that high performance supercapacitor electrodes with a specific capacitance of ∼192 F/g along with a maximum energy density of ∼3.8 W h/kg and a power density of ∼28 kW/kg can be achieved by synthesizing zinc oxide nanowires (ZnO NWs) directly on top of aligned multi-walled carbon nanotubes (MWCNTs). In comparison to pristine MWCNTs, these constitute a 12-fold of increase in specific capacitance as well as corresponding power and energy density values. These electrodes also possess high cycling stability and were able to retain ∼99% of their specific capacitance value over 2000 charging discharging cycles. These findings indicate potential use of a MWCNT/ZnO NW hybrid material for future electrochemical energy storage applications
High photoresponse of individual WS₂ nanowire-nanoflake hybrid materials
Abstract
van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS₂ nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to ∼0.4 AW⁻¹ are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices
Aligned multi-walled carbon nanotube-embodied hydrogel via low magnetic field:a strategy for engineering aligned injectable scaffolds
Abstract
Injectable scaffolds are a promising strategy to restore and regenerate damaged and diseased tissues. They require minimally invasive procedure and allow the formation of an in-situ structure of any shape. However, the formation of 3D in-situ structure with aligned morphologies using a method which could be easily transferred to clinical settings remains a challenge. Herein, the rational design of an aligned injectable hydrogel-based scaffold via remote-induced alignment is reported. Carboxylated multi-walled carbon nanotubes (cMWCNT) are aligned into hydrogel via low magnetic field. The uniform dispersion and alignment of cMWCNT into the hydrogel are clearly demonstrated by small angle neutron scattering. The obtained aligned cMWCNT-embodied hydrogel is stable over 7 days at room temperature and as well at body temperature (i.e. 37 °C). As unique approach, the formation of MWCNT-hydrogel composite is investigated combining rheology with molecular dynamic and quantum mechanical calculations. The increase of MWCNT concentration into the hydrogel decreases the total energy promoting structural stabilization and increase of stiffness. The remote aligning of injectable hydrogel-based scaffold opens up horizons in the engineering of functional tissues which requires specific cell orientation
Conversion of Industrial Bio-Waste into Useful Nanomaterials
Chromium-complexed collagen is generated
as waste during processing
of skin into leather. Here, we report a simple heat treatment process
to convert this hazardous industrial waste into core–shell
chromium–carbon nanomaterials having a chromium-based nanoparticle
core encapsulated by partially graphitized nanocarbon layers that
are self-doped with oxygen and nitrogen functionalities. We demonstrate
that these core–shell nanomaterials can be potentially utilized
in electromagnetic interference (EMI) shielding application or as
a catalyst in aza-Michael addition reaction. The results show the
ability to convert industrial bio-waste into useful nanomaterials,
suggesting new scalable and simple approaches to improve environmental
sustainability in industrial processes