Nanomaterials

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10 pages, 1756 KiB

Open AccessArticle

Sulfur-Doped Reduced Graphene Oxide for Enhanced Sodium Ion Pseudocapacitance

by Yiting Wang, Mingxiang Hu, Desheng Ai, Hongwei Zhang, Zheng-Hong Huang, Ruitao Lv and Feiyu Kang

Nanomaterials 2019, 9(5), 752; https://doi.org/10.3390/nano9050752 - 16 May 2019

Cited by 17 | Viewed by 3618

Abstract

Sodium-ion capacitors (NICs) are considered an important candidate for large-scale energy storage in virtue of their superior energy–power properties, as well as availability of rich Na⁺ reserves. To fabricate high-performance NIC electrode material, a hydrothermal method was proposed to synthesize sulfur-doped reduced [...] Read more.

Sodium-ion capacitors (NICs) are considered an important candidate for large-scale energy storage in virtue of their superior energy–power properties, as well as availability of rich Na⁺ reserves. To fabricate high-performance NIC electrode material, a hydrothermal method was proposed to synthesize sulfur-doped reduced graphene oxide (SG), which exhibited unique layered structures and showed excellent electrochemical properties with 116 F/g capacitance at 1 A/g as the cathode of NICs from 1.6 V to 4.2 V. At the power–energy density over 5000 W/kg, the SG demonstrated over 100 Wh/kg energy density after 3500 cycles, which indicated its efficient durability and superior power–energy properties. The addition of a sulfur source in the hydrothermal process led to the higher specific surface area and more abundant micropores of SG when compared with those of reduced graphene oxide (rGO), thus SG exhibited much better electrochemical properties than those shown by rGO. Partially substituting surface oxygen-containing groups of rGO with sulfur-containing groups also facilitated the enhanced sodium-ion storage ability of SG by introducing sufficient pseudocapacitance. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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22 pages, 7549 KiB

Open AccessArticle

Multifunctional Superparamagnetic Stiff Nanoreservoirs for Blood Brain Barrier Applications

by Zulema Vargas-Osorio, Andrés Da Silva-Candal, Yolanda Piñeiro, Ramón Iglesias-Rey, Tomas Sobrino, Francisco Campos, José Castillo and José Rivas

Nanomaterials 2019, 9(3), 449; https://doi.org/10.3390/nano9030449 - 17 Mar 2019

Cited by 16 | Viewed by 3462

Abstract

Neurological diseases (Alzheimer’s disease, Parkinson’s disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for [...] Read more.

Neurological diseases (Alzheimer’s disease, Parkinson’s disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for selective imaging. However, the strong isolation of the brain by the brain blood barrier (BBB) prevents not only the crossing of pathogens, but also a large set of beneficial drugs. Therefore, an alternative strategy is arising based on the anchoring to vascular endothelial cells of nanoplatforms working as delivery reservoirs. In this work, novel injectable mesoporous nanorods, wrapped by a fluorescent magnetic nanoparticles envelope, are proposed as biocompatible reservoirs with an extremely high loading capacity, surface versatility, and optimal morphology for enhanced grafting to vessels during their diffusive flow. Wet chemistry techniques allow for the development of mesoporous silica nanostructures with tailored properties, such as a fluorescent response suitable for optical studies, superparamagnetic behavior for magnetic resonance imaging MRI contrast, and large range ordered porosity for controlled delivery. In this work, fluorescent magnetic mesoporous nanorods were physicochemical characterized and tested in preliminary biological in vitro and in vivo experiments, showing a transversal relaxivitiy of 324.68 mM⁻¹ s⁻¹, intense fluorescence, large specific surface area (300 m² g⁻¹), and biocompatibility for endothelial cells’ uptake up to 100 µg (in a 80% confluent 1.9 cm² culture well), with no liver and kidney disability. These magnetic fluorescent nanostructures allow for multimodal MRI/optical imaging, the allocation of therapeutic moieties, and targeting of tissues with specific damage. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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15 pages, 2779 KiB

Open AccessArticle

Novel Magnetic Nanostructured Beads for Cadmium(II) Removal

by Lisandra de Castro Alves, Susana Yáñez-Vilar, Yolanda Piñeiro-Redondo and José Rivas

Nanomaterials 2019, 9(3), 356; https://doi.org/10.3390/nano9030356 - 04 Mar 2019

Cited by 26 | Viewed by 3821

Abstract

This study presents an effective magnetic separation method for cadmium removal, based on the use of a novel nanostructured material as an adsorbent. This adsorbent involves the incorporation of magnetite nanoparticles (Fe₃O₄-NPs), synthesized by the reverse coprecipitation method, into [...] Read more.

This study presents an effective magnetic separation method for cadmium removal, based on the use of a novel nanostructured material as an adsorbent. This adsorbent involves the incorporation of magnetite nanoparticles (Fe₃O₄-NPs), synthesized by the reverse coprecipitation method, into sodium alginate and activated carbon to form spherical structures by crosslinking Ca²⁺ ions with the charged alginate chains, referred to as magnetic alginate activated carbon (MAAC) beads. The effect of the experimental parameters, such as pH, contacting time, adsorbent dosage, agitation type, and rotating speed were investigated and optimized for an efficient removal of Cd(II) ions at an initial concentration of 250 mg/L. The amount of adsorbed Cd(II) by MAAC beads increased at a pH of 6 with a removal efficiency over 90%. The maximum adsorption capacity reached was 70 mg/g of adsorbent at an initial Cd(II) concentration of 150 mg/L, whereas at 250 mg/L the adsorption capacity lowered until 60 mg/g. Sorption isotherms were calculated using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich equations, and were better described by the Freundlich and Temkin models. These results proved the removal efficiency and the potential use under real environmental conditions of the MAAC beads, due to their easy recovery from contaminated aqueous solutions. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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14 pages, 5165 KiB

Open AccessArticle

Removal of Tetracycline Pollutants by Adsorption and Magnetic Separation Using Reduced Graphene Oxide Decorated with α-Fe₂O₃ Nanoparticles

by Adriana Magdalena Huízar-Félix, Celia Aguilar-Flores, Azael Martínez-de-la Cruz, José Manuel Barandiarán, Selene Sepúlveda-Guzmán and Rodolfo Cruz-Silva

Nanomaterials 2019, 9(3), 313; https://doi.org/10.3390/nano9030313 - 26 Feb 2019

Cited by 73 | Viewed by 5376

Abstract

Nanocomposites of reduced graphene oxide (RGO) with ferromagnetic α-Fe₂O₃ nanoparticles have been prepared in-situ by thermal treatment. The structure and morphology of the hybrid material were studied by X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and transmission electron microscopy. The results [...] Read more.

Nanocomposites of reduced graphene oxide (RGO) with ferromagnetic α-Fe₂O₃ nanoparticles have been prepared in-situ by thermal treatment. The structure and morphology of the hybrid material were studied by X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and transmission electron microscopy. The results show a hybrid material highly modified with α-Fe₂O₃ nanoparticles distributed on the graphene surface. The adsorption kinetics show the presence of α-Fe₂O₃ nanoparticles on the RGO surface, and the amount of remaining functional groups dominated by ionization and dispersion. The adsorption kinetics of this adsorbent was characterized and found to fit the pseudo-second-order model. The α-Fe₂O₃ nanoparticles on RGO modify the electrostatic interaction of RGO layers and tetracycline, and adsorption properties decreased in the hybrid material. Adsorption isotherms fit with the Langmuir model very well, and the maximum capacity adsorption was 44.23 mg/g for RGO and 18.47 mg/g for the hybrid material. Magnetic characterization of the hybrid material shows ferromagnetic behavior due to the nanosize of α-Fe₂O₃ with a saturation magnetization, Ms = 7.15 Am²/kg, a remanence Mr = 2.29 Am²/kg, and a coercive field, Hc = 0.02 T. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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11 pages, 6346 KiB

Open AccessArticle

Bi-Metal Phosphide NiCoP: An Enhanced Catalyst for the Reduction of 4-Nitrophenol

by Lijie Sun, Xia Xiang, Juwei Wu, Chao Cai, Dongyi Ao, Jinling Luo, Chengxiang Tian and Xiaotao Zu

Nanomaterials 2019, 9(1), 112; https://doi.org/10.3390/nano9010112 - 18 Jan 2019

Cited by 8 | Viewed by 5380

Abstract

Porous phosphide Ni_xCo_yP composite nanomaterials are successfully synthesized at different Ni/Co ratios (=0, 0.5, 1, and 2) to reduce 4-nitrophenol. The X-ray diffraction and X-ray photoelectron spectroscopy results demonstrate that the products are CoP, NiCoP/CoP, NiCoP, and NiCoP/Ni₂ [...] Read more.

Porous phosphide Ni_xCo_yP composite nanomaterials are successfully synthesized at different Ni/Co ratios (=0, 0.5, 1, and 2) to reduce 4-nitrophenol. The X-ray diffraction and X-ray photoelectron spectroscopy results demonstrate that the products are CoP, NiCoP/CoP, NiCoP, and NiCoP/Ni₂P when the Ni/Co ratio is 0, 0.5, 1, and 2, respectively. The products exhibit different catalytic performance for reduction of 4-nitrophenol at room temperature. Among them, the pure NiCoP delivers a better catalytic efficiency with

k_{app} = 677.4 \times 10^{- 2} \min^{- 1}

and

k = 338.7 ({Lg}^{- 1} \min^{- 1})

, due to the synergy between Ni and Co atoms. The sequence of catalytic efficiency of different samples is CoP < NiCoP/CoP < NiCoP/Ni₂P < NiCoP. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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10 pages, 2135 KiB

Open AccessArticle

Thickness-Dependent Differential Reflectance Spectra of Monolayer and Few-Layer MoS₂, MoSe₂, WS₂ and WSe₂

by Yue Niu, Sergio Gonzalez-Abad, Riccardo Frisenda, Philipp Marauhn, Matthias Drüppel, Patricia Gant, Robert Schmidt, Najme S. Taghavi, David Barcons, Aday J. Molina-Mendoza, Steffen Michaelis De Vasconcellos, Rudolf Bratschitsch, David Perez De Lara, Michael Rohlfing and Andres Castellanos-Gomez

Nanomaterials 2018, 8(9), 725; https://doi.org/10.3390/nano8090725 - 14 Sep 2018

Cited by 158 | Viewed by 18003

Abstract

The research field of two dimensional (2D) materials strongly relies on optical microscopy characterization tools to identify atomically thin materials and to determine their number of layers. Moreover, optical microscopy-based techniques opened the door to study the optical properties of these nanomaterials. We [...] Read more.

The research field of two dimensional (2D) materials strongly relies on optical microscopy characterization tools to identify atomically thin materials and to determine their number of layers. Moreover, optical microscopy-based techniques opened the door to study the optical properties of these nanomaterials. We presented a comprehensive study of the differential reflectance spectra of 2D semiconducting transition metal dichalcogenides (TMDCs), MoS₂, MoSe₂, WS₂, and WSe₂, with thickness ranging from one layer up to six layers. We analyzed the thickness-dependent energy of the different excitonic features, indicating the change in the band structure of the different TMDC materials with the number of layers. Our work provided a route to employ differential reflectance spectroscopy for determining the number of layers of MoS₂, MoSe₂, WS₂, and WSe₂. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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21 pages, 8249 KiB

Open AccessArticle

A Mild and Facile Synthesis of Amino Functionalized CoFe₂O₄@SiO₂ for Hg(II) Removal

by Xi Wang, Zhenzong Zhang, Yuhao Zhao, Kai Xia, Yongfu Guo, Zan Qu and Renbi Bai

Nanomaterials 2018, 8(9), 673; https://doi.org/10.3390/nano8090673 - 29 Aug 2018

Cited by 47 | Viewed by 3794

Abstract

To avoid the dangerous operational conditions, shorten the preparation time, and improve the adsorption performance of amino-functionalized nanomagnetic materials with a core–shell structure, a magnetic nanocomposite of CoFe₂O₄@SiO₂ was successfully functionalized with amino group (−NH₂) through [...] Read more.

To avoid the dangerous operational conditions, shorten the preparation time, and improve the adsorption performance of amino-functionalized nanomagnetic materials with a core–shell structure, a magnetic nanocomposite of CoFe₂O₄@SiO₂ was successfully functionalized with amino group (−NH₂) through a mild and facile hydrothermal method without the use of any toxic or harmful solvents at a relatively low temperature. The preparation time of the key steps of amino functionalization was shortened from 30 h to about 10 h. The core-shell structure and successful grafting were confirmed by various means. The amino-functionalized CoFe₂O₄@SiO₂ was used for the removal mercury (Hg(II)), a heavy metal, and exhibited excellent magnetic properties and a high Langmuir adsorption capacity of 149.3 mg Hg(II)/g. The adsorption of Hg(II) onto CoFe₂O₄@SiO₂–NH₂ followed the pseudo-second-order kinetic equation and Langmuir model. The thermodynamic data showed that the Hg(II) adsorption process was achieved through spontaneous exothermic and monolayer adsorption with electrostatic adsorption and chemisorption. In addition, the as-prepared CoFe₂O₄@SiO₂–NH₂ nanoparticles had a good reusable value, good application performance and stability, and can provide a mild and facile way to remove heavy metals from aqueous solution. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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14 pages, 2710 KiB

Open AccessArticle

Plasmonic Sensor Based on Interaction between Silver Nanoparticles and Ni²⁺ or Co²⁺ in Water

by Federico Mochi, Luca Burratti, Ilaria Fratoddi, Iole Venditti, Chiara Battocchio, Laura Carlini, Giovanna Iucci, Mauro Casalboni, Fabio De Matteis, Stefano Casciardi, Silvia Nappini, Igor Pis and Paolo Prosposito

Nanomaterials 2018, 8(7), 488; https://doi.org/10.3390/nano8070488 - 02 Jul 2018

Cited by 55 | Viewed by 4524

Abstract

Silver nanoparticles capped with 3-mercapto-1propanesulfonic acid sodium salt (AgNPs-3MPS), able to interact with Ni²⁺ or Co²⁺, have been prepared to detect these heavy metal ions in water. This system works as an optical sensor and it is based on the [...] Read more.

Silver nanoparticles capped with 3-mercapto-1propanesulfonic acid sodium salt (AgNPs-3MPS), able to interact with Ni²⁺ or Co²⁺, have been prepared to detect these heavy metal ions in water. This system works as an optical sensor and it is based on the change of the intensity and shape of optical absorption peak due to the surface plasmon resonance (SPR) when the AgNPs-3MPS are in presence of metals ions in a water solution. We obtain a specific sensitivity to Ni²⁺ and Co²⁺ up to 500 ppb (part per billion). For a concentration of 1 ppm (part per million), the change in the optical absorption is strong enough to produce a colorimetric effect on the solution, easily visible with the naked eye. In addition to the UV-VIS characterizations, morphological and dimensional studies were carried out by transmission electron microscopy (TEM). Moreover, the systems were investigated by means of dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and high-resolution X-ray photoelectron spectroscopy (HR-XPS). On the basis of the results, the mechanism responsible for the AgNPs-3MPS interaction with Ni²⁺ and Co²⁺ (in the range of 0.5–2.0 ppm) looks like based on the coordination compounds formation. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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Review

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20 pages, 3739 KiB

Open AccessReview

Chemical and Bio Sensing Using Graphene-Enhanced Raman Spectroscopy

by Alexander Silver, Hikari Kitadai, He Liu, Tomotaroh Granzier-Nakajima, Mauricio Terrones, Xi Ling and Shengxi Huang

Nanomaterials 2019, 9(4), 516; https://doi.org/10.3390/nano9040516 - 02 Apr 2019

Cited by 29 | Viewed by 6239

Abstract

Graphene is a two-dimensional (2D) material consisting of a single sheet of sp² hybridized carbon atoms laced in a hexagonal lattice, with potentially wide usage as a Raman enhancement substrate, also termed graphene-enhanced Raman scattering (GERS), making it ideal for sensing applications. [...] Read more.

Graphene is a two-dimensional (2D) material consisting of a single sheet of sp² hybridized carbon atoms laced in a hexagonal lattice, with potentially wide usage as a Raman enhancement substrate, also termed graphene-enhanced Raman scattering (GERS), making it ideal for sensing applications. GERS improves upon traditional surface-enhanced Raman scattering (SERS), combining its single-molecule sensitivity and spectral fingerprinting of molecules, and graphene’s simple processing and superior uniformity. This enables fast and highly sensitive detection of a wide variety of analytes. Accordingly, GERS has been investigated for a wide variety of sensing applications, including chemical- and bio-sensing. As a derivative of GERS, the use of two-dimensional materials other than graphene for Raman enhancement has emerged, which possess remarkably interesting properties and potential wider applications in combination with GERS. In this review, we first introduce various types of 2D materials, including graphene, MoS₂, doped graphene, their properties, and synthesis. Then, we describe the principles of GERS and comprehensively explain how the GERS enhancement factors are influenced by molecular and 2D material properties. In the last section, we discuss the application of GERS in chemical- and bio-sensing, and the prospects of such a novel sensing method. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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25 pages, 29101 KiB

Open AccessReview

Environmental Remediation Applications of Carbon Nanotubes and Graphene Oxide: Adsorption and Catalysis

by Yanqing Wang, Can Pan, Wei Chu, Adavan Kiliyankil Vipin and Ling Sun

Nanomaterials 2019, 9(3), 439; https://doi.org/10.3390/nano9030439 - 15 Mar 2019

Cited by 121 | Viewed by 11086

Abstract

Environmental issues such as the wastewater have influenced each aspect of our lives. Coupling the existing remediation solutions with exploring new functional carbon nanomaterials (e.g., carbon nanotubes, graphene oxide, graphene) by various perspectives shall open up a new venue to understand the environmental [...] Read more.

Environmental issues such as the wastewater have influenced each aspect of our lives. Coupling the existing remediation solutions with exploring new functional carbon nanomaterials (e.g., carbon nanotubes, graphene oxide, graphene) by various perspectives shall open up a new venue to understand the environmental issues, phenomenon and find out the ways to get along with the nature. This review makes an attempt to provide an overview of potential environmental remediation solutions to the diverse challenges happening by using low-dimensional carbon nanomaterials and their composites as adsorbents, catalysts or catalysts support towards for the social sustainability. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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18 pages, 6876 KiB

Open AccessReview

Controlling Nitrogen Doping in Graphene with Atomic Precision: Synthesis and Characterization

by Tomotaroh Granzier-Nakajima, Kazunori Fujisawa, Vivek Anil, Mauricio Terrones and Yin-Ting Yeh

Nanomaterials 2019, 9(3), 425; https://doi.org/10.3390/nano9030425 - 12 Mar 2019

Cited by 64 | Viewed by 8495

Abstract

Graphene provides a unique platform for the detailed study of its dopants at the atomic level. Previously, doped materials including Si, and 0D-1D carbon nanomaterials presented difficulties in the characterization of their dopants due to gradients in their dopant concentration and agglomeration of [...] Read more.

Graphene provides a unique platform for the detailed study of its dopants at the atomic level. Previously, doped materials including Si, and 0D-1D carbon nanomaterials presented difficulties in the characterization of their dopants due to gradients in their dopant concentration and agglomeration of the material itself. Graphene’s two-dimensional nature allows for the detailed characterization of these dopants via spectroscopic and atomic resolution imaging techniques. Nitrogen doping of graphene has been well studied, providing insights into the dopant bonding structure, dopant-dopant interaction, and spatial segregation within a single crystal. Different configurations of nitrogen within the carbon lattice have different electronic and chemical properties, and by controlling these dopants it is possible to either n- or p-type dope graphene, grant half-metallicity, and alter nitrogen doped graphene’s (NG) catalytic and sensing properties. Thus, an understanding and the ability to control different types of nitrogen doping configurations allows for the fine tuning of NG’s properties. Here we review the synthesis, characterization, and properties of nitrogen dopants in NG beyond atomic dopant concentration. Full article

(This article belongs to the Special Issue Low Dimensional Materials for Environmental and Biomedical Applications)

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