Microporous metal-organic frameworks (MOFs) that display permanent porosity show great promise for a myriad of purposes. The potential applications of MOFs can be developed further and extended by encapsulating various functional species (for example, nanoparticles) within the frameworks. However, despite increasing numbers of reports of nanoparticle/MOF composites, simultaneously to control the size, composition, dispersed nature, spatial distribution and confinement of the incorporated nanoparticles within MOF matrices remains a significant challenge. Here, we report a controlled encapsulation strategy that enables surfactant-capped nanostructured objects of various sizes, shapes and compositions to be enshrouded by a zeolitic imidazolate framework (ZIF-8). The incorporated nanoparticles are well dispersed and fully confined within the ZIF-8 crystals. This strategy also allows the controlled incorporation of multiple nanoparticles within each ZIF-8 crystallite. The as-prepared nanoparticle/ZIF-8 composites exhibit active (catalytic, magnetic and optical) properties that derive from the nanoparticles as well as molecular sieving and orientation effects that originate from the framework material.

Integration of two-dimensional (2D) nanometer-scale building blocks, such as graphene sheets, into 3D macroscopic structures (e.g., layered fi lms and porous scaffolds) is attracting much attention since it is an essential step in exploring the advanced properties of individual 2D sheets for practical applications. For instance, freestanding graphene macroscopic structures have shown unique catalytic, electrochemical, and mechanical properties together with potential applications in chemical fi lters and electrodes for energy storage devices. [ 6-8 , 11 , 30 ] However, in most cases, during the process of assembling nanometerscale building blocks into macroscopic paper-like structures, the large accessible surface area of 2D graphene sheets is lost. The reason for this is that the individual graphene sheets tend to irreversibly aggregate and restack owing to the strong ππ stacking and van der Waals force between the planar basal planes of graphene sheets. This reduces the potential applications of graphene materials in electrochemical electrodes, composite materials, and so on. [ 20 ] Therefore, preventing aggregation of graphene sheets in the macroscopic structures, such that the properties of the individual graphene sheets are not compromised, is a critical challenge in constructing functional graphene-based macroscopic structures. Currently, a number of strategies for preventing aggregation have been developed, which include adding spacers (e.g., surfactants, nanoparticles, polymers), [27][28][29][30][31][32][33][34][35][36] template-assisted growth, [ 37 ] and crumpling the graphene sheets. [ 18 , 38 ] Alternatively, several groups have reported the formation of freestanding 3D graphene-based macroscopic structures without the assistance of any spacers or templates. [ 7 , 39,40 ] For instance, Li and coworkers reported the preparation of freestanding multilayered graphene fi lms by vacuum-assisted fi ltration based on the effective prevention of graphene intersheet restacking. [ 7 ] Shi and coworkers demonstrated the formation of a 3D graphene hydrogel by a hydrothermal method. [ 39 ] However, preparing freestanding and fl exible graphene fi lms with large accessible surface area but without complicated processing by overcoming the aggregation of graphene sheets remains a challenge.Leavening is the process of adding gas before or during baking or steaming to produce lighter, more easily chewable bread with porous structure from the more compact dough. Inspired by this, we thought leavening could be an effective approach to transforming compact graphene structures to porous structures if we could fi nd a suitable "leavening" procedure. In earlier work, using the vacuum fi ltration method, Ruoff and coworkers successfully prepared graphene oxide (GO) compact layered fi lms, [ 11 ] which could be regarded as "dough". It is known that GO is rather unstable and can be chemically reduced under mild heating to yield reduced GO (rGO) and gaseous species such as H 2 O and CO 2 . [41][42][43][44] Therefore, if the ...

Electrochromic (EC) materials and polymer electrolytes are the most imperative and active components in an electrochromic device (ECD). EC materials are able to reversibly change their light absorption properties in a certain wavelength range via redox reactions stimulated by low direct current (dc) potentials of the order of a fraction of volts to a few volts. The redox switching may result in a change in color of the EC materials owing to the generation of new or changes in absorption band in visible region, infrared or even microwave region. In ECDs the electrochromic layers need to be incorporated with supportive components such as electrical contacts and ion conducting electrolytes. The electrolytes play an indispensable role as the prime ionic conduction medium between the electrodes of the EC materials. The expected applications of the electrochromism in numerous fields such as reflective-type display and smart windows/mirrors make these materials of prime importance. In this article we have reviewed several examples from our research work as well as from other researchers' work, describing the recent advancements on the materials that exhibit visible electrochromism and polymer electrolytes for electrochromic devices. The first part of the review is centered on nanostructured inorganic and conjugated polymer-based organic-inorganic hybrid EC materials. The emphasis has been to correlate the structures, morphologies and interfacial interactions of the EC materials to their electronic and ionic properties that influence the EC properties with unique advantages. The second part illustrates the perspectives of polymer electrolytes in electrochromic applications with emphasis on poly (ethylene oxide) (PEO), poly (methyl methacrylate) (PMMA) and polyvinylidene difluoride (PVDF) based polymer electrolytes. The requirements and approaches to optimize the formulation of electrolytes for feasible electrochromic devices have been delineated.

We demonstrate a simple and scalable strategy for synthesizing hierarchical porous NiCo(2)O(4) nanowires which exhibit a high specific capacitance of 743 F g(-1) at 1 A g(-1) with excellent rate performance (78.6% capacity retention at 40 A g(-1)) and cycling stability (only 6.2% loss after 3000 cycles).

We report the synthesis of uniform crystalline WO 3 nanorods and their assembly without any surfactants. WO 3 nanorods have been synthesized by using a facile hydrothermal process without employing lithium ions and sulfates. Transparent WO 3 nanorod film has been prepared by assembled coating of the as-synthesized WO 3 nanorods suspension onto ITO coated glass. It is found that the assembly was not affected by the surface properties of substrates, but dependent on the drying rate of the film, the concentration of suspension, and the aspect ratio of nanorods. The assembly process is proposed to follow an aggregation-deposition mechanism. The resulting WO 3 nanorod film exhibits high electrochromic stability and comparable color display, contrast, and coloration/bleaching response.