Molecular‐Scale Heteroassembly of Redoxable Hydroxide Nanosheets and Conductive Graphene into Superlattice Composites for High‐Performance Supercapacitors

Ma, Renzhi; Liu, Xiaohe; Liang, Jianbo; Bandô, Yoshio; Sasaki, Takayoshi

doi:10.1002/adma.201400054

Cited by 167 publications

(147 citation statements)

References 45 publications

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“…If the crystallographic thicknesses of GO (0.78 nm, shown in Figure 2d) and the LDH host layer (0.48 nm) are taken into account, a basal spacing of 1.26 nm is expected for a superlattice structure containing intercalated water, which is close to the value obtained here. The slightly reduced basal spacing can be attributed to the interlayer contraction originating from electrostatic attractions between the oppositely charged NS 46,47 and the loss of intercalated water in the interlayer galleries. The latter can be demonstrated by the relatively hydrophobic surface of the GO/LDH-NS hybrid membrane (Co-Al) (contact angle:~64°) compared with that of the GO membrane (contact angle:~44°).…”

Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

“…[39][40][41][42][43][44][45] Because of the in-plane positive charges of LDH-NS, superlattice composites can be expected via alternative face-to-face assembly of cationic LDH-NS and anionic GO-NS on a molecular scale. 46,47 With these superlattice units, a macroscopic membrane may be constructed, in which the cationic LDH-NS are intercalated uniformly into the GO galleries, acting as both strengthening phases for electrostatic interactions and interlayer phases for modifying the physicochemical properties of the nanochannels. This unique structural feature may give rise to significant separations of small ions solely dependent on their charges.…”

Section: Introductionmentioning

confidence: 99%

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Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Sun

et al. 2016

NPG Asia Mater

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The development of graphene-based functional membranes with the ability to effectively filter and separate molecules or ions in solutions based on a simple criterion (for example, the size or charge of solutes) is crucial for various engineering-relevant applications, ranging from wastewater purification and reuse to chemical refinement. Here, we report a hybrid membrane consisting of anionic graphene oxide (GO) and cationic Co-Al (or Mg-Al) layered double hydroxide (LDH) nanosheet (NS) superlattice units for high selectivity charge-guided ion transport. The hybrid membrane possesses a series of characteristics, including being easy to access, mechanically robust, freestanding, flexible and semitransparent as well as having a large area. The interlayer spacing of the hybrid membrane is insensitive to humidity variations, ensuring the structural stability in solution-based mass transport applications. The concentration gradient-driven ion transmembrane diffusion experiments show that the cations bearing various valences can be effectively separated strictly according to their charges, independent of the cationic and charge-balancing anionic species. The relative selectivity of the hybrid membranes toward monovalent and trivalent cations is as high as 30, which is not achievable by GO multilayer stacks, LDH-NS multilayer stacks or their bulk-stratified membranes, indicating that a synergistic effect originating from the molecular-level heteroassembly of GO and LDH-NS has a dominant role in the high-performance charge-guided ion filtration and separation processes. These excellent properties of GO/LDH-NS hybrid membranes make them promising candidates in diverse applications, ranging from wastewater treatment and reuse and chemical refinement to biomimetic selective ion transport.

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Section: Results and Discussion Preparation Of Go-ns Ldh-ns And Go/lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Sun

et al. 2016

NPG Asia Mater

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“…These self-assembly prepared hybrids also present additional weak harmonics, as well as (100), (110) and (113) peaks showing that the structure of the LDH nanosheets is maintained as recently reported in a HT/rGO hybrid. 16,17 . Besides, the small harmonics found in these samples at lower 2θ angles (marked by arrows in Figure 1A) reinforce the hypothesis of formation of a sandwichtype superstructure.…”

Section: Resultsmentioning

confidence: 99%

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Álvarez

Tichit

Medina

et al. 2017

Applied Surface Science

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Layered double hydroxides (LDH or HT) or their derived mixed oxides present marked acid-base properties useful in catalysis, but they tend to agglomerate inducing a weak accessibility to the active sites. In this study we report the preparation and characterization of HT/Graphene (HT/rGO) nanocomposites as active and selective basic catalysts for the acetone condensation reaction. The graphene high specific surface area and structural compatibility with the HT allowed increasing the number and accessibility of the active sites and activity. Two series of HT/rGO nanocomposites with 0.5≤HT/rGO≤10 mass ratio were prepared by: i) direct HT coprecipitation in the presence of GO; ii) self-assembly of preformed HT with GO. The prepared HT/rGO nanocomposites were dried either in air at 80 °C or freeze-dried. A series of characterizations showed the great influence of the preparation method and HT/rGO mass ratio on both the nanocomposite structure and catalytic activity. An optimum activity was observed for a HT/rGO = 10 catalyst. Particularly, the highest catalytic activity was found in those nanocomposites obtained by coprecipitation and freeze dried (3 times more active than bulk HT) which can be connected to their structure with a better accessibility to the basic sites.2

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“…25 Moreover, a growing selection of layered oxides and hydroxides are showing great promise in this area. 3,[26][27][28][29][30][31][32][33][34][35] To best employ the high intrinsic pseudocapacitance of any material requires the maximum number of redox active sites be in contact with the electrolyte and therefore available for charge storage. This makes the layered oxides described above extremely attractive so long as they can be exfoliated into thin flakes.…”

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confidence: 99%

Effect of Percolation on the Capacitance of Supercapacitor Electrodes Prepared from Composites of Manganese Dioxide Nanoplatelets and Carbon Nanotubes

et al. 2014

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Here we demonstrate significant improvements in the performance of supercapacitor electrodes based on 2D MnO2 nano-platelets by the addition of carbon nanotubes. Electrodes based on MnO2 nano-platelets do not display high areal capacitance because the electrical properties of such films are poor, limiting the transport of charge between redox sites and the external circuit.In addition, the mechanical strength is low, limiting the achievable electrode thickness, even in the presence of binders. By adding carbon nanotubes to the MnO2-based electrodes, we have increased the conductivity by up to eight orders of magnitude, in line with percolation theory.The nanotube network facilitates charge transport, resulting in large increases in capacitance, especially at high rates, around 1 V/s. The increase in MnO2 specific capacitance scaled with nanotube content in a manner fully consistent with percolation theory. Importantly, the mechanical robustness was significantly enhanced, allowing the fabrication of electrodes that were 10 times thicker than could be achieved in MnO2-only films. This resulted in composite films with areal capacitances up to 40 times higher than could be achieved with MnO2-only electrodes.

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Molecular‐Scale Heteroassembly of Redoxable Hydroxide Nanosheets and Conductive Graphene into Superlattice Composites for High‐Performance Supercapacitors

Cited by 167 publications

References 45 publications

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Effect of Percolation on the Capacitance of Supercapacitor Electrodes Prepared from Composites of Manganese Dioxide Nanoplatelets and Carbon Nanotubes

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