Ternary Self-Assembly of Ordered Metal Oxide−Graphene Nanocomposites for Electrochemical Energy Storage

Abstract

N anocomposites have attracted wide attention because of their potential to combine desirable properties of different nanoscale building blocks to improve mechanical, optical, electronic , or magnetic properties. 16 Most traditional synthesis approaches of nanocom-posites rely on mechanical or chemical mixing and produce a random distribution of the constitutive phases. To address these problems, several groups recently investigated layer-by-layer deposition and other techniques to prepare layered nanocom-posites with ceramics, clays, and graphite oxide nanoplatelets, 79 but these methods are lacking in nanoscale spatial precision and are time-consuming and difficult for bulk-materials synthesis. On the other hand, biological systems abound with nanocom-posites that possess well-controlled archi-tectures based on multiple scale and multi-functional building blocks. 10 One powerful approach to achieve similar control is to use amphiphilic polymer or surfactant to direct the self-assembly of nanostructured metal oxides, semiconductors, and polymer materials. 1115 There has been a growing interest in incorporating functional components , such as functional groups, polymers, and nanoparticles, into the self-assembled nanostructures, but success has been limited to two-phase organic/inorganic hybrid materials, nanoparticles, or polymer-based nanocomposites. 4,5,16,17 Recently, a range of nanoscale building blocks, including carbon nanotubes 1821 and graphene, 2224 have gained prominence. Graphene and graphene stacks (mul-tilayer graphene), potentially low cost alternative materials to single-wall or multiwall carbon nanotubes, have unique electronic conductivity and mechanical properties. 2527 Graphene-based nanocom-posites with polymer, metal, or metal oxides have also shown unique mechanical, electronic , and electrochemical properties. 23,2835 We focus on the nano-composites made of metal oxides (i.e., SnO 2 , NiO, MnO 2 , and SiO 2) that could have important applications for electrochemical energy storage. 36,37 The low conductivity and poor stability of such materials usually necessitate adding conductive phases to enhance electron transport and electrical contact of the active materials in the electrode of a Li-ion battery. In most of these studies, the approach used to prepare the composite materials has been mechanical mixing of metal oxides with conductive materials such as amorphous carbon, carbon nano-tubes, and graphene. 31,38 In spite of these studies, a well-controlled architecture of the conductive material and metal oxide is difficult to achieve because of improper ABSTRACT Surfactant or polymer directed self-assembly has been widely investigated to prepare nanostructured metal oxides, semiconductors, and polymers, but this approach is mostly limited to two-phase materials, organic/inorganic hybrids, and nanoparticle or polymer-based nanocomposites. Self-assembled nanostructures from more complex, multiscale, and multiphase building blocks have been investigated with limited success. Here, we demonstr...

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

“…This was the fi rst evidence of the drawbacks of RGO binder-free electrodes. Indeed, it was subsequently found that, in absence of binder, the 1 st cycle irreversible specifi c capacity was always higher than 40% [37][38][39][40][41] and, in some cases, the binder-free electrodes were very fragile and diffi cult to handle. [ 41 ] Despite few research efforts starting the good practice of reporting the electrodes' active material loadings, [ 35,42 ] still the focus was only on gravimetric capacity, and no indication on volumetric values was given.…”

“…In 2010, the further progression of graphene-based host structures (i.e., hollow GO spheres, [ 43 ] RGO, [ 37,39,[44][45][46][47][48][49][50] unzipped CNT, [ 51 ] bottom-up-synthesized graphene, [ 52 ] CVD-synthesized graphene [ 40 ] and N-doped graphene [ 40 ] ) only enabled limited progresses (Table 1 ). However, some major advances in understanding the Li-ion storage mechanism in different kinds of graphene were reported.…”

Experimental Sensing and Density Functional Theory Study of H2S and SOF2 Adsorption on Au‐Modified Graphene

“…Graphene is a promising material for various applications, such as energy storage,7 nanoelectronic devices,8 fuel cells,9 and capacitors,10 because it features very high electron mobility caused by linear dispersion relation in the band structure of the π and π * states around the Dirac point in the Brillouin zone 11. Graphene sheets have been increasingly used as transducers since the first successful attempt to apply graphene for chemical sensing and detection of single‐gas molecular absorption and desorption on graphene platforms 12.…”

Self‐Assembled Graphene‐Based Architectures and Their Applications

“…The AuCN nanowires could align themselves along the zigzag lattice direction of graphene, which originated from the interaction with the gold atom and the lattice match suggested by the first‐principles calculations. Dangling bonds of damaged graphene,132, 133 vapor‐phase deposition at high temperature,134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148 and intermediate seed materials132, 148, 149, 150 have been used to produce the hybrid of pristine graphene/inorganic nanostructure; however, the formed inorganic nanostructures were randomly oriented or poorly aligned on pristine graphene. This work paves a new way for precisely assembling inorganic nanomaterials on pristine graphene 93, 135, 136, 137, 138, 139…”

“…Zhang and co‐workers141 recently demonstrated that the well‐dispersed mesoporous TiO 2 nanocrystals with (001) facets could be assembled onto a graphene aerogel surface (TiO 2 /GAs) by a one‐pot hydrothermal treatment. In this process, the glucose functioned as not only the linker but also the face‐regulating agent to yield (001) facets as well as a mesoporous TiO 2 structure.…”