An Effective Way to Optimize the Functionality of Graphene-Based Nanocomposite: Use of the Colloidal Mixture of Graphene and Inorganic Nanosheets

Abstract

The best electrode performance of metal oxide-graphene nanocomposite material for lithium secondary batteries can be achieved by using the colloidal mixture of layered CoO 2 and graphene nanosheets as a precursor. The intervention of layered CoO 2 nanosheets in-between graphene nanosheets is fairly effective in optimizing the pore and composite structures of the Co 3 O 4 -graphene nanocomposite and also in enhancing its electrochemical activity via the depression of interaction between graphene nanosheets. The resulting CoO 2 nanosheet-incorporated nanocomposites show much greater discharge capacity of ~1750 mAhg −1 with better cyclability and rate characteristics than does CoO 2 -free Co 3 O 4 -graphene nanocomposite (~1100 mAhg −1 ). The huge discharge capacity of the present nanocomposite is the largest one among the reported data of cobalt oxide-graphene nanocomposite. Such a remarkable enhancement of electrode performance upon the addition of inorganic nanosheet is also observed for Mn 3 O 4 -graphene nanocomposite. The improvement of electrode performance upon the incorporation of inorganic nanosheet is attributable to an improved Li + ion diffusion, an enhanced mixing between metal oxide and graphene, and the prevention of electrode agglomeration. The present experimental findings underscore an efficient and universal role of the colloidal mixture of graphene and redoxable metal oxide nanosheets as a precursor for improving the electrode functionality of graphene-based nanocomposites.Graphene-based nanocomposite is one of the most currently investigated materials in the fields of chemistry, physics, materials science, and nanotechnology because of its intriguing physicochemical properties and promising functionalities [1][2][3][4] . This family of materials boasts excellent functionalities for many energy-related applications such as secondary batteries, supercapacitors, photocatalysts, photovoltaics, and fuel cells [4][5][6][7][8][9][10][11][12] . One of the most promising applications of the graphene-based nanocomposites is an electrode for secondary batteries. An increasing demand for the large-scale application of secondary batteries evokes intense research efforts for the exploration of novel graphene-based electrode materials showing excellent rate characteristics and high electrochemical stability 11 . The hybridization of electrode materials with highly conductive graphene nanosheets leads to a significant improvement of electrode performance at high current density via the increase of electrical conductivity 12 . Additionally the porous stacking structure of the graphene-based nanocomposite can relieve the drastic volume change and

Reductive hybridization route with exfoliated graphene oxide and MoS2 nanosheets to efficient electrode materials

“…In high wavenumber region, both the nanohybrids exhibit the peak 2D related to the degree of the structural disorder and stacking of graphene at $2700 cm À1 (Fig. 4c) [27,29]. In comparison with the nanohybrid prepared with rG-O, that with G-O displays a slight red-shift of this 2D peak, indicating the depression of the numbers of stacked graphene layers and better dispersion of graphene nanosheet in this material.…”

“…5b). Both the nanohybrids and restacked MoS 2 possess mesopores with the average sizes of $3-5 nm, which is formed by the house-of-cards-type stacking structure of nanosheets [18,20,29].…”

A 2D Metal Oxide Nanosheet as an Efficient Additive for Improving Na‐Ion Electrode Activity of Graphene‐Based Nanocomposites

“…[12,13] Judging from the 2D sheet-like morphology of metal dichalcogenide, the composite formation with ah ighly conductive graphene 2D nanosheet is supposed to provide an effective approach to improve the sodium-ion electrode functionality of metal dichalcogenidet hrough the enhancement of electrical conductivity.A lthought here are several reports about the coupling of metal dichalcogenide with reduced graphene oxide (rG-O), [14][15][16] the strong self-stackingt endency of rG-O prevents it from intimately mixing with metal dichalcogenide nanosheets. Because exfoliated metal oxide nanosheets can form ah omogenousc olloidal mixture with rG-O duet ot heir similar surfacen ature and crystal morphology, [17][18][19] this metal oxide nanosheet can be easily incorporated into the restacked rG-O matrix. The intervention of am etal oxide nanosheet gives rise to the optimization of the pore structure of metal dichalcogenide-rG-On anocomposites by preventing the severe selfstacking of rG-O nanosheets.…”

“…The intervention of am etal oxide nanosheet gives rise to the optimization of the pore structure of metal dichalcogenide-rG-On anocomposites by preventing the severe selfstacking of rG-O nanosheets. [17][18][19] The resulting increase of porosity with surface expansion leads to more reaction sites for the anchoring of Na + ions and the improvemento fN a + ion transport, therebyi ncreasing the Na-ion storage capacity.T he accompanying enhanced electronic coupling of metal chalcogenide with metallic rG-O upon incorporation of am etal oxide nanosheet is also beneficiali ne nhancing the electrode functionality of metal dichalcogenide-rG-O nanocomposites. Yet, to the best of our knowledge, there is no report about the use of an exfoliated metal oxide nanosheet as an additive for the synthesis of efficient NIB anode materials.…”

Effects of graphene oxide on the formation, structure and properties of bionanocomposite films made from wheat gluten with chitosan

“…Although its applications are limited due to the agglomeration of the graphene nanosheets, which inhibits their dispersion in a polymer matrix, graphene can be oxidized to improve its dispersion in water . Graphene oxide (GO) prepared in this way contains polar groups that make it hydrophilic, which allows the dispersion of GO in water and improves the ability of GO to combine with (bio)polymers; these (bio)nanocomposites demonstrate significantly improved mechanical and thermal properties …”