Hierarchical Nanocomposites Derived from Nanocarbons and Layered Double Hydroxides ‐ Properties, Synthesis, and Applications

Abstract

A good arrangement and construction of different low-dimensional nanomaterials (e.g., zero-dimensional (0D) nanoparticles (NPs), one-dimensional (1D) nanotubes, nanowires, nanorods, and two-dimensional (2D) flakes) as building blocks with two or more levels from the nanometer to the macroscopic scale leads to the formation of three-dimensional (3D) hierarchical nanocomposites. Hierarchical composites are widely observed in nature, e.g., in plant cell walls, bone, animal shells, and skeletons, showing that a high mechanical performance can be obtained by structuring matter across a range of length scales. The combination of low-dimensional nanomaterials with distinct physical and chemical properties into a composite with hierarchical structures can usually inherit full advantages of the component materials, or even lead to the formation of multifunctional materials with unexpected properties for unique applications. For instance, the combined clay/polymer, [1] carbon nanotube (CNT)/polymer, [2,3] or graphene/ polymer [4] nanocomposites show significantly improved mechanical, electrical, and energy-absorbing properties. Clay/ CNT nanocomposites obtained by growing CNTs on clays were demonstrated to be much more excellent nanofillers for polymer reinforcement [5] and were with better oil adsorption properties [6,7] compared with either clay or CNTs separately. They can even serve as an advanced material for shock-absorbing applications. [8] Tailored assembly of 1D CNTs and 2D graphene into 3D architectures can further explore the utilization and improve the performance of graphitic carbon materials in nanoelectronics, sensors, and energy storage/conversion devices. [9,10] Exploring hierarchical composites with multifunctional properties through combining various building blocks together into a well-designed structure has always been a hot topic for material science. Among various building blocks, nanocarbons and layered double hydroxides (LDHs) were intensly investigated recently. On one hand, nanocarbon materials including fullerene, CNTs, and graphene, have been of great interest in the physics, chemistry, and materials communities since the first discovery of fullerene in 1985. Recently, the rapid progress of graphene and graphene-based materials has again triggered tremendous interest in 2D nanomaterials. On the other hand, LDHs are amongst the most studied advanced functional materials Hierarchical Nanocomposites Derived from Nanocarbons and Layered Double Hydroxides -Properties, Synthesis, and ApplicationsThe combination of one-dimensional and two-dimensional building blocks leads to the formation of hierarchical composites that can take full advantages of each kind of material, which is an effective way for the preparation of multifunctional materials with extraordinary properties. Among various building blocks, nanocarbons (e.g., carbon nanotubes and graphene) and layered double hydroxides (LDHs) are two of the most powerful materials that have been widely used in human life. This Feature Article present...

Characteristics, Preparation Routes and Metallurgical Applications of LDHs: An Overview

“…Moreover, some research works appeared on the possible recovery of adsorbates, such as As(V), 3 4 PO − and Cr(VI) from spent LDHs [75,96,97]. Gillman [96] reported that the minute amount of As in the As-loaded LDHs could be easily recovered by saturating As-loaded LDHs with phosphate, while Kuzawa et al [95] proposed a scheme whereby the desorbed 3 4 PO − in the spent desorption solution could be recovered as calcium phosphate precipitate by addition of CaCl 2 , and the remaining spent desorption solution could also be reused after supplementing additional NaOH ( Figure 5) [98,99].…”

Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

“…Various methods have been explored to overcome these problems, such as the combination of LDH with carbon nanofibers [14] and carbon nanotubes [15][16][17][18][19][20], as previously studied in our group [21]. Among the nanocarbons, the 2D geometry of graphene oxide (GO) is obviously compatible with the layered structure of LDHs and there is also a charge compatibility between the positively charged LDH and negatively charged GO.…”

“…Among the nanocarbons, the 2D geometry of graphene oxide (GO) is obviously compatible with the layered structure of LDHs and there is also a charge compatibility between the positively charged LDH and negatively charged GO. The large size of GO sheets compared to LDH platelets implies that it may be possible to form an open network with large pores allowing access of the reactants to the active LDH sites which is helpful for the high rate conversion of the reactants [15]. When combining LDH with GO, the heat and mass transfers during a reaction can be greatly improved.…”

Modular Polyoxometalate‐Layered Double Hydroxide Composites as Efficient Oxidative Catalysts

“…[12][13][14][15] Owing to the specific structure and versatility in chemical composition, LDHs have been widely used as multi-functional materials in the fields of photocatalytic water splitting and degradation of environmental pollutants etc. [16,17] Previous work have demonstrated that the intercalation of polyoxometalates (POMs) into LDHs inter-lamellar gallery can effectively depress the aggregation, enhance the dispersion and stability of the guests. [18][19][20][21][22] Most importantly, compared with other immobilized systems such as SiO2/POMs, ZrO2/POMs, Al2O3/POMs etc, the LDHs/POMs nanocomposites would exhibit the following advantages: (1) the host-guest interactions (e.g., electrostatic, van der Waals, or hydrogen bonding) induce a homogeneous distribution of POMs guests at the molecular level; (2) the chemical stability and photo-stability of POMs can be largelyimproved by the introduction of inorganic LDH component; (3) the POM-leaching issue for many heterogeneous catalysts is not pronounced after intercalation.…”