α-MnO2 nanowires as building blocks for the construction of 3D macro-assemblies

Long, Yong; Hui, Junfeng; Wang, Pengpeng; Hu, Shengsun; Xu, Biao; Xiang, Guolei; Zhuang, Jing; Lü, Xingqiang; Wang, Xun

doi:10.1039/c2cc32162a

Cited by 29 publications

(29 citation statements)

References 23 publications

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“…34,35 In our case, OH on the surface of manganese oxide could form hydrogen bonds with H 2 O. 36,37 The ultralong nanowires (more than 100 μm) entangle with each other, and the hydrogen bonds serve as the bonding force during entangling. Finally, this self-assembled free-standing MnO 2 membrane is obtained.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires

Lan

Lin

et al. 2013

ACS Appl. Mater. Interfaces

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In this work, we report the preparation of a free-standing membrane with strong mechanical stability and flexibility through a facile vacuum filtration approach. A field-emission scanning electron microscopy image demonstrates that the membrane composed of MnO2 nanowires is 50 nm in width and up to 100 μm long and the nanowires are assembled in parallel into bundles. A possible formation mechanism for the ultralong nanowires and the free-standing membrane has been proposed. Meanwhile, the properties of the membrane could be controlled by incorporating different materials to achieve composite membranes. In order to demonstrate the broad applicability of the MnO2 membrane, we fabricate a variety of composite membranes exhibiting various novel properties including magnetism and reversibly switchable wettability between hydrophilicity and hydrophobicity through various material modification, including CoFe2O4 nanoparticles and organic triethoxy(octyl)silane. Furthermore, the free-standing membrane could also simultaneously be functionalized with two materials, which reveal multiple properties. The synthesis method of a free-standing MnO2 membrane is simple and environmentally friendly, and it is easily scalable for industry. These composite membranes constitute a significant contribution to advanced technology.

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Section: ■ Results and Discussionmentioning

confidence: 97%

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires

Lan

Lin

et al. 2013

ACS Appl. Mater. Interfaces

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“…As the concentration decreases via dilution and filtration, the porosity increases and the density decreases. Especially, the aerogel from D has an extremely low density of 2.9 mg/cm 3 that is 17 times lower than the one of the previously reported MnO 2 nanowire block 13 and only slightly higher than an air density of 1.2 mg/cm 3 ( Figure 1f). As we have found previously, the nanowire gel formation concentration depends on the aspect ratio of the nanowires.…”

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confidence: 81%

“…In particular, the uptake capability 0.36 g/g for Pb 2+ ions shows selectively higher efficiency than other metal ions, possibly due to the negative surface charge and the inherent tunnel structures of manganese oxide. 13 Also in Figure 4d, the absorption test using different absorbent dosages of 0.02, 0.04, 0.06, 0.08, and 0.1 g cryptomelane nanowire hydrogels shows exceptionally high removal of 47, 87.8, 100, 100, and 100%, respectively. The uptake capability from the absorption test (calculated from the slope of Figure 4d) is found to be 0.6 g/g, which is the highest absorption value, when compared with previous reported values.…”

Section: Nano Lettersmentioning

confidence: 99%

“…Basically, the hydrothermal method grows the nanotubes/nanowires at elevated temperatures and under pressures in aqueous solutions 11,12 and the resulting material has been used to make nanowire blocks 13 or nanowire membranes 14−21 with limited surface area and porosity. Here, we used this method to directly produce high surface area and highly porous inorganic nanowire hydrogels/ aerogels based on the principle of the gel formation in our previous work.…”

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confidence: 99%

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A Facile Methodology for the Production of In Situ Inorganic Nanowire Hydrogels/Aerogels

Jung

Fang

et al. 2014

Nano Lett.

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Creating inorganic nanowire hydrogels/aerogels using various materials and inexpensive means remains an outstanding challenge despite their importance for many applications. Here, we present a facile methodology to enable highly porous inorganic nanowire hydrogel/aerogel production on a large scale and at low cost. The hydrogels/aerogels are obtained from in situ hydrothermal synthesis of onedimensional (1D) nanowires that directly form a cross-linking network during the synthesis process. Such a method not only offers great simplicity but also allows the interconnecting nanowires to have much longer length. The longer length offers aerogels with remarkable porosity and surface area extremely low densities (as low as 2.9 mg/cm 3 ), are mechanically robust, and can have superelasticity by tuning the synthesis conditions. The nanowires in the hydrogels/aerogels serve both as structural support and active sites, for example, for catalysis or absorption. In this work, we have found that the as-grown hydrogels can be used directly as water filters to remove pollutants such as heavy metal ions and toxic organic contents. Our studies indicate that this method for nanowire hydrogels/aerogels production is not only economical but greatly augmented their applications in environmental, catalysis, sensing, absorption, energy storage, and beyond. KEYWORDS: Inorganic nanowires, hydrogels, aerogels, superelasticity, water purification filters P orous inorganic nanowire hydrogels/aerogels are highly attractive in applications for energy generation and storage, sensing, catalytic conversion, selective absorption and removal, or thermal insulation, and so forth.1−4 General syntheses of the inorganic nanowire aerogels have been demonstrated with template-assisted deposition followed by a template removal step such as metal electrodeposition onto a polymer template, 5 or atomic layer deposition of a metal oxide onto nanocellulose 6 or a copolymer 7 template. However, these methods are complicated and are limited in terms of porosity 8 without collapsing of the three-dimensional (3D) network during the template removal process. Because the pore geometry and pore size play a critical role in the properties and performance of these porous materials, 9 this hampers their utilization for various applications.Previously, we demonstrated that highly porous inorganic nanowire hydrogels/aerogels can be obtained by assembling the nanowires into a cross-linking network from their colloidal suspensions at the transition from semidilute to isotropic concentrated regimes without using templates or supporting materials. 10 The synthesized nanowires were initially dispersed with/without surfactant in ethanol using ultrasonication at a dilute concentration, and then the suspension was transformed into a nanowire gel by evaporating the solvent to reach the gel formation concentration (φ gel = a r −1, where a r is the nanowire aspect ratio, a r = L/d, and L is the nanowire length and d is the diameter).10 For this method, in the case of bri...

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“…The high surface energy of these powders results in their significant aggregation and agglomeration. Therefore, freezing and subsequent freeze-drying are often applied as a final stage of the hydrothermal synthesis process to prevent aggregation and agglomeration [93][94][95][96][97][98][99][100][101].…”

Section: Cryogels For Particle Isolationmentioning

confidence: 99%

Inorganic Cryogels

Shlyakhtin¹

2014

Polymeric Cryogels

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α-MnO2 nanowires as building blocks for the construction of 3D macro-assemblies

Cited by 29 publications

References 23 publications

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires

A Facile Methodology for the Production of In Situ Inorganic Nanowire Hydrogels/Aerogels

Inorganic Cryogels

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α-MnO2 nanowires as building blocks for the construction of 3D macro-assemblies

Cited by 29 publications

References 23 publications

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO2 Nanowires

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO2 Nanowires

A Facile Methodology for the Production of In Situ Inorganic Nanowire Hydrogels/Aerogels

Inorganic Cryogels

Contact Info

Product

Resources

About

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires

Multifunctional Free-Standing Membrane from the Self-assembly of Ultralong MnO₂ Nanowires