Nanomaterials

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17 pages, 1906 KiB

Open AccessArticle

Numerical Simulation of a Time-Dependent Electroviscous and Hybrid Nanofluid with Darcy-Forchheimer Effect between Squeezing Plates

by Muhammad Sohail Khan, Sun Mei, Shabnam, Unai Fernandez-Gamiz, Samad Noeiaghdam and Aamir Khan

Nanomaterials 2022, 12(5), 876; https://doi.org/10.3390/nano12050876 - 6 Mar 2022

Cited by 25 | Viewed by 2154

Abstract

In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid

{MoS}_{2} + Au

/

C_{2} H_{6} O_{2} - H_{2} O

was formulated by dissolving the components of [...] Read more.

In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid

{MoS}_{2} + Au

/

C_{2} H_{6} O_{2} - H_{2} O

was formulated by dissolving the components of an inorganic substance such as molybdenum disulfide

({MoS}_{2})

and gold (Au) in a base fluid of ethylene glycol/water. This hybrid non-liquid flow was modeled by various nonlinear mathematical fluid flow models and subsequently solved by numerical as well as analytical methods. For the numerical solution of nonlinear ODEs, a built-in function BVP4C was used in MATLAB, and the same problem was solved in MATHEMATICA by HAM. The result of the present problem related to the results obtained from the existing literature under certain conditions. The outcomes revealed that the concentration profiles were more sensitive to homogeneity diversity parameters. The simulation of the various physical parameters of the model indicated that the heat transfer through a mixture of hybrid nanofluids was greater than a simple nanofluid. In addition, the phenomenon of mixed convection was considered to improve the velocity of simple nanofluids and hybrid nanofluids, when both cases have low permeability. A rise in the volume fraction of the nanomaterials,

Φ

, was associated with an increase in the heat transfer rate. It was observed that the heat transfer rate of the hybrid nanofluids

{MoS}_{2} + {Au / C}_{2} H_{6} O_{2} - H_{2} O

was higher than that of the single nanofluids

{MoS}_{2} / C_{2} H_{6} O_{2} - H_{2} O

. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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15 pages, 10157 KiB

Open AccessArticle

Nanocomposites of Rigid Polyurethane Foam and Graphene Nanoplates Obtained by Exfoliation of Natural Graphite in Polymeric 4,4′-Diphenylmethane Diisocyanate

by Se-Ra Shin and Dai-Soo Lee

Nanomaterials 2022, 12(4), 685; https://doi.org/10.3390/nano12040685 - 18 Feb 2022

Cited by 10 | Viewed by 2084

Abstract

The influence of graphene nanoplates (GNPs) obtained by the ecofriendly exfoliation of natural graphite has been addressed on the mechanical and thermal insulating properties of rigid polyurethane foams (RPUFs). Few-layer GNPs with few defects were prepared in polymeric 4,4′-diphenylmethane diisocyanate (pMDI) under ultrasonication [...] Read more.

The influence of graphene nanoplates (GNPs) obtained by the ecofriendly exfoliation of natural graphite has been addressed on the mechanical and thermal insulating properties of rigid polyurethane foams (RPUFs). Few-layer GNPs with few defects were prepared in polymeric 4,4′-diphenylmethane diisocyanate (pMDI) under ultrasonication to obtain a GNP/pMDI dispersion. GNP/pMDI dispersions with different GNP concentrations were used to prepare RPUF nanocomposites via in situ polymerization. An important finding is that the GNP/pMDI dispersion exhibits lyotropic liquid crystalline behavior. It was found that the unique orientation of GNPs above the concentration of 0.1 wt% in the dispersion affected the mechanical and thermal insulation properties of the RPUF nanocomposites. GNP/RPUF nanocomposites with GNP concentrations at 0.2 wt% or more showed better thermal insulating properties than neat RPUF. The lyotropic liquid crystalline ordering of GNPs provides stable nucleation for bubble formation during foaming and prevents bubble coalescence. This decreases the average cell size and increases the closed cell content, producing GNP/RPUF nanocomposites with low thermal conductivity. Furthermore, GNPs incorporated into RPUF act as a barrier to radiant heat transfer through the cells, which effectively reduces the thermal conductivity of the resulting nanocomposites. It is expected that the nanocomposite of RPUF investigated in this study can be applied practically to improve the performance of thermal insulation foams. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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10 pages, 2132 KiB

Open AccessArticle

Fabrication of Transparent and Conductive SWCNT/SiO₂ Composite Thin-Film by Photo-Irradiation of Molecular Precursor Films

by Naoki Ogawa, Hiroki Nagai, Yukihiro Kudoh, Takeyoshi Onuma, Taichi Murayama, Akinobu Nojima and Mitsunobu Sato

Nanomaterials 2021, 11(12), 3404; https://doi.org/10.3390/nano11123404 - 16 Dec 2021

Cited by 1 | Viewed by 2415

Abstract

A single-walled carbon nanotube (SWCNT)-silica composite thin film on a quartz glass was formed by ultraviolet irradiation (20–40 °C) onto a spin-coated precursor film. With 7.4 mass% SWCNTs, the electrical resistivity reached 7.7 × 10⁻³ Ω·cm after UV-irradiation. The transmittance was >80% [...] Read more.

A single-walled carbon nanotube (SWCNT)-silica composite thin film on a quartz glass was formed by ultraviolet irradiation (20–40 °C) onto a spin-coated precursor film. With 7.4 mass% SWCNTs, the electrical resistivity reached 7.7 × 10⁻³ Ω·cm after UV-irradiation. The transmittance was >80% at 178–2600 nm, and 79%–73% at 220–352 nm. Heat treatment increased the transparency and pencil hardness, without affecting the low electrical resistivity. Raman spectroscopy and microscopic analyses revealed the excellent film morphology with good SWCNT dispersal. The low refractive index (1.49) and haze value (<1.5%) are invaluable for transparent windows for novel optoelectronic devices. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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13 pages, 3446 KiB

Open AccessEditor’s ChoiceArticle

Facile Fabrication of Single-Walled Carbon Nanotube/Anatase Composite Thin Film on Quartz Glass Substrate for Translucent Conductive Photoelectrode

by Yutaka Suwazono, Takuro Murayoshi, Hiroki Nagai and Mitsunobu Sato

Nanomaterials 2021, 11(12), 3352; https://doi.org/10.3390/nano11123352 - 10 Dec 2021

Cited by 4 | Viewed by 2358

Abstract

A single-walled carbon nanotube/anatase (SWCNT/anatase) composite thin film with a transmittance of over 70% in the visible-light region was fabricated on a quartz glass substrate by heat treating a precursor film at 500 °C in air. The precursor film was formed by spin [...] Read more.

A single-walled carbon nanotube/anatase (SWCNT/anatase) composite thin film with a transmittance of over 70% in the visible-light region was fabricated on a quartz glass substrate by heat treating a precursor film at 500 °C in air. The precursor film was formed by spin coating a mixed solution of the titania molecular precursor and well-dispersed SWCNTs (0.075 mass%) in ethanol. The anatase crystals and Ti³⁺ ions in the composite thin films were determined by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The effect of the heating process on the SWCNTs was analyzed using Raman spectroscopy. The composite film showed an even surface with a scratch resistance of 4H pencil hardness, as observed using field-emission scanning electron microscopy and atomic force microscopy. The electrical resistivity and optical bandgap energy of the composite thin film with a thickness of 100 nm were 6.6 × 10⁻² Ω cm and 3.4 eV, respectively, when the SWCNT content in the composite thin film was 2.9 mass%. An anodic photocurrent density of 4.2 μA cm⁻² was observed under ultraviolet light irradiation (16 mW cm⁻² at 365 nm) onto the composite thin film, thus showing excellent properties as a photoelectrode without conductive substrates. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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10 pages, 2007 KiB

Open AccessArticle

Tungsten-Modulated Molybdenum Selenide/Graphene Heterostructure as an Advanced Electrode for All-Solid-State Supercapacitors

by Qixian Liu, Jing Ning, Haibin Guo, Maoyang Xia, Boyu Wang, Xin Feng, Dong Wang, Jincheng Zhang and Yue Hao

Nanomaterials 2021, 11(6), 1477; https://doi.org/10.3390/nano11061477 - 2 Jun 2021

Cited by 21 | Viewed by 3046

Abstract

Transition metal dichalcogenides (TMDs) have attracted widespread attention due to their excellent electrochemical and catalytic properties. In this work, a tungsten (W)-modulated molybdenum selenide (MoSe₂)/graphene heterostructure was investigated for application in electrochemistry. MoSe₂/graphene heterojunctions with low-doped W compositions were [...] Read more.

Transition metal dichalcogenides (TMDs) have attracted widespread attention due to their excellent electrochemical and catalytic properties. In this work, a tungsten (W)-modulated molybdenum selenide (MoSe₂)/graphene heterostructure was investigated for application in electrochemistry. MoSe₂/graphene heterojunctions with low-doped W compositions were synthesized by a one-step hydrothermal catalysis approach. Based on the conducted density functional theory (DFT) calculations, it was determined that inserting a small amount of W (≈5%) into the MoSe₂/graphene heterostructure resulted in the modification of its lattice structure. Additionally, an increase in the distance between layers (≈8%) and a decrease in the adsorption energy of the potassium ions (K⁺) (≈−1.08 eV) were observed following W doping. Overall, the electrochemical performance of the MoSe₂/graphene hybrid was enhanced by the presence of W. An all-solid-state supercapacitor device prepared using electrodes based on the W-doped MoSe₂/graphene composite achieved excellent capacitance of 444.4 mF cm⁻² at 1 mV s⁻¹. The results obtained herein revealed that the MoSe₂/graphene hybrid exhibiting low W composition could be valuable in the field of energy storage and isoelectronic doping of TMDs. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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9 pages, 1469 KiB

Open AccessArticle

Deep-Ultraviolet Transparent Conductive MWCNT/SiO₂ Composite Thin Film Fabricated by UV Irradiation at Ambient Temperature onto Spin-Coated Molecular Precursor Film

by Hiroki Nagai, Naoki Ogawa and Mitsunobu Sato

Nanomaterials 2021, 11(5), 1348; https://doi.org/10.3390/nano11051348 - 20 May 2021

Cited by 3 | Viewed by 2643

Abstract

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO₂ matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet [...] Read more.

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO₂ matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet (UV) irradiation (4 mW cm⁻² at 254 nm) for more than 6 h at 20−40 °C onto the precursor films, which were obtained by spin coating with a mixed solution of MWCNT in water and Si(IV) complex in ethanol. The electrical resistivity of MWCNT/SiO₂ composite thin film is 0.7 Ω·cm, and transmittance in the wavelength region from DUV to visible light is higher than 80%. The MWCNT/SiO₂ composite thin film showed scratch resistance at pencil hardness of 8H. Importantly, the resistivity of the MWCNT/SiO₂ composite thin film was maintained at the original level even after heat treatment at 500 °C for 1 h. It was observed that the heat treatment of the composite thin film improved durability against both aqueous solutions involving a strong acid (HCl) and a strong base (NaOH). Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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9 pages, 2866 KiB

Open AccessArticle

Epoxy Nanocomposites with Carbon Nanotubes Produced by Floating Catalyst CVD

by Vladimir Z. Mordkovich, Stanislav V. Kondrashov, Aida R. Karaeva, Sergey A. Urvanov, Nikita V. Kazennov, Eduard B. Mitberg and Ekaterina A. Pushina

Nanomaterials 2021, 11(5), 1213; https://doi.org/10.3390/nano11051213 - 4 May 2021

Viewed by 2216

Abstract

Epoxy nanocomposites with float catalysis-produced CNT felt as a filler were prepared. Parameters such as the curing process, glass transition of epoxynanocomposites, structure and morphology of CNT felt, initial epoxy composition, and epoxy nanocomposites were investigated. The influence of CNT felt on curing [...] Read more.

Epoxy nanocomposites with float catalysis-produced CNT felt as a filler were prepared. Parameters such as the curing process, glass transition of epoxynanocomposites, structure and morphology of CNT felt, initial epoxy composition, and epoxy nanocomposites were investigated. The influence of CNT felt on curing process in epoxy nanocomposites with different amounts of curing agent was determined. An exothermic reaction between the curing agent and the surface of CNTs was established. It was found that the structure of epoxy nanocomposites has a high degree of heterogeneity: the presence of fiber-like structures and individualized CNTs is observed together with the regions that are typical for CNTs that are fabricated via a catalytic chemical vapor deposition (CVD). Based on the studies performed, it is possible to predict the production of epoxy nanocomposites with outstanding mechanical and thermophysical properties. In particular, the uncured compositions already obtained in this work can be used for the manufacture of electrically conductive glass and carbon fiber reinforced plastics and functional coatings. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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10 pages, 16986 KiB

Open AccessFeature PaperArticle

Biocompatible, Electroconductive, and Highly Stretchable Hybrid Silicone Composites Based on Few-Layer Graphene and CNTs

by Marie N. Barshutina, Valentyn S. Volkov, Aleksey V. Arsenin, Dmitriy I. Yakubovsky, Alexander V. Melezhik, Alexander N. Blokhin, Alexey G. Tkachev, Alexander V. Lopachev and Vladislav A. Kondrashov

Nanomaterials 2021, 11(5), 1143; https://doi.org/10.3390/nano11051143 - 28 Apr 2021

Cited by 7 | Viewed by 3111

Abstract

In this paper, we report a cost-effective and scalable approach to produce highly homogeneous graphene and CNT-based silicone composites with potential applications in diverse fields of research, including biosensors and wearable electronics. This approach includes the fabrication of hybrid fillers based on few-layer [...] Read more.

In this paper, we report a cost-effective and scalable approach to produce highly homogeneous graphene and CNT-based silicone composites with potential applications in diverse fields of research, including biosensors and wearable electronics. This approach includes the fabrication of hybrid fillers based on few-layer graphene and CNTs by water solution blending and manufacturing of graphene/CNT/PDMS composites through calendering in a three-roll mill. The influence of processing parameters, the graphene/CNT ratio, and hybrid filler loading was thoroughly investigated, and the optimal parameters for producing hybrid composites with superior electrical and mechanical properties were found. It was also confirmed that the graphene/CNT hybrid system exhibits a synergistic effect of non-covalent interactions between graphene sheets and CNT sidewalls. This synergistic effect prevents the aggregation of graphene sheets, facilitates the dispersion of graphene and CNTs in the silicone matrix, and contributes to the superior properties of hybrid composites compared to composites with either of these fillers alone. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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Review

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28 pages, 8359 KiB

Open AccessReview

Carbon Material-Based Aerogels for Gas Adsorption: Fabrication, Structure Design, Functional Tailoring, and Applications

by Lianming Zhang, Yu Lei, Peng He, Hao Wu, Lei Guo and Gang Wei

Nanomaterials 2022, 12(18), 3172; https://doi.org/10.3390/nano12183172 - 13 Sep 2022

Cited by 10 | Viewed by 2889

Abstract

Carbon material-based aerogels (CMBAs) have three-dimensional porous structure, high specific surface area, low density, high thermal stability, good electric conductivity, and abundant surface-active sites, and, therefore, have shown great application potential in energy storage, environmental remediation, electrochemical catalysis, biomedicine, analytical science, electronic devices, [...] Read more.

Carbon material-based aerogels (CMBAs) have three-dimensional porous structure, high specific surface area, low density, high thermal stability, good electric conductivity, and abundant surface-active sites, and, therefore, have shown great application potential in energy storage, environmental remediation, electrochemical catalysis, biomedicine, analytical science, electronic devices, and others. In this work, we present recent progress on the fabrication, structural design, functional tailoring, and gas adsorption applications of CMBAs, which are prepared by precursor materials, such as polymer-derived carbon, carbon nanotubes, carbon nanofibers, graphene, graphene-like carbides, fullerenes, and carbon dots. To achieve this aim, first we introduce the fabrication methods of various aerogels, and, then, discuss the strategies for regulating the structures of CMBAs by adjusting the porosity and periodicity. In addition, the hybridization of CMBAs with other nanomaterials for enhanced properties and functions is demonstrated and discussed through presenting the synthesis processes of various CMBAs. After that, the adsorption performances and mechanisms of functional CMBAs towards CO₂, CO, H₂S, H₂, and organic gases are analyzed in detail. Finally, we provide our own viewpoints on the possible development directions and prospects of this promising research topic. We believe this work is valuable for readers to understand the synthesis methods and functional tailoring of CMBAs, and, meanwhile, to promote the applications of CMBAs in environmental analysis and safety monitoring of harmful gases. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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41 pages, 4369 KiB

Open AccessReview

Current Understanding of Water Properties inside Carbon Nanotubes

by Aris Chatzichristos and Jamal Hassan

Nanomaterials 2022, 12(1), 174; https://doi.org/10.3390/nano12010174 - 5 Jan 2022

Cited by 30 | Viewed by 5448

Abstract

Confined water inside carbon nanotubes (CNTs) has attracted a lot of attention in recent years, amassing as a result a very large number of dedicated studies, both theoretical and experimental. This exceptional scientific interest can be understood in terms of the exotic properties [...] Read more.

Confined water inside carbon nanotubes (CNTs) has attracted a lot of attention in recent years, amassing as a result a very large number of dedicated studies, both theoretical and experimental. This exceptional scientific interest can be understood in terms of the exotic properties of nanoconfined water, as well as the vast array of possible applications of CNTs in a wide range of fields stretching from geology to medicine and biology. This review presents an overreaching narrative of the properties of water in CNTs, based mostly on results from systematic nuclear magnetic resonance (NMR) and molecular dynamics (MD) studies, which together allow the untangling and explanation of many seemingly contradictory results present in the literature. Further, we identify still-debatable issues and open problems, as well as avenues for future studies, both theoretical and experimental. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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22 pages, 3831 KiB

Open AccessReview

Growth, Properties, and Applications of Branched Carbon Nanostructures

by Sharali Malik and Silvia Marchesan

Nanomaterials 2021, 11(10), 2728; https://doi.org/10.3390/nano11102728 - 15 Oct 2021

Cited by 10 | Viewed by 2641

Abstract

Nanomaterials featuring branched carbon nanotubes (b-CNTs), nanofibers (b-CNFs), or other types of carbon nanostructures (CNSs) are of great interest due to their outstanding mechanical and electronic properties. They are promising components of nanodevices for a wide variety of advanced applications spanning from batteries [...] Read more.

Nanomaterials featuring branched carbon nanotubes (b-CNTs), nanofibers (b-CNFs), or other types of carbon nanostructures (CNSs) are of great interest due to their outstanding mechanical and electronic properties. They are promising components of nanodevices for a wide variety of advanced applications spanning from batteries and fuel cells to conductive-tissue regeneration in medicine. In this concise review, we describe the methods to produce branched CNSs, with particular emphasis on the most widely used b-CNTs, the experimental and theoretical studies on their properties, and the wide range of demonstrated and proposed applications, highlighting the branching structural features that ultimately allow for enhanced performance relative to traditional, unbranched CNSs. Full article

(This article belongs to the Special Issue Research of Carbon Nanomaterials and Nanocomposites)

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