Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.

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.

Thermoelectric materials can directly generate electrical power from waste heat but the challenge is in designing efficient, stable and inexpensive systems. Nanostructuring in bulk materials dramatically reduces the thermal conductivity but simultaneously increases the charge carrier scattering, which has a detrimental effect on the carrier mobility. We have experimentally achieved concurrent phonon blocking and charge transmitting via the endotaxial placement of nanocrystals in a thermoelectric material host. Endotaxially arranged SrTe nanocrystals at concentrations as low as 2% were incorporated in a PbTe matrix doped with Na(2)Te. This effectively inhibits the heat flow in the system but does not affect the hole mobility, allowing a large power factor to be achieved. The crystallographic alignment of SrTe and PbTe lattices decouples phonon and electron transport and this allows the system to reach a thermoelectric figure of merit of 1.7 at ~800 K.

Chemical vapor deposition is used to prepare novel 3D graphene networks, with ethanol as the carbon source. These networks are used as templates for the construction of graphene/metal oxide composite‐based supercapacitor electrodes. As a proof of concept, NiO is deposited on 3D graphene networks. The product exhibits a high specific capacitance of about 816 F g−1 at a scan rate of 5 mV s−1 and good cycling performance.

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Monocrystalline ZnO nanorods (NRs) with high donor concentration are electrochemically deposited on highly conductive reduced graphene oxide (rGO) films on quartz. The film thickness, optical transmittance, sheet resistance, and roughness of rGO films are systematically studied. The obtained ZnO NRs on rGO films are characterized by X-ray diffraction, transmission electron microscopy, photoluminescence, and Raman spectra. As a proof-of-concept application, the obtained ZnO NRs on rGO are used to fabricate inorganic-organic hybrid solar cells with layered structure of quartz/rGO/ZnO NR/poly(3-hexylthiophene)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (P3HT/PEDOT:PSS)/Au. The observed power conversion efficiency (PCE, eta), approximately 0.31%, is higher than that reported in previous solar cells by using graphene films as electrodes. These results clearly demonstrate that rGO films with a higher conductivity have a smaller work function and show a better performance in the fabricated solar cells.

energy-storage systems with high specific energy, long lifespan, and excellent safety. [5][6][7] Among them, the rechargeable secondary batteries have been demonstrated as the most promising candidate for electricity storage and utilization. [8][9][10][11] As one of the most popular batteries, lithium-ion batteries (LIBs) have found immense success in consumer electronics and electric vehicles, and are under the consideration for energy-storage power stations. [12][13][14] However, the commercial LIBs based on transition metal-based inorganic compounds have encountered a bottleneck. [15][16][17] The charge storage of inorganic electrode materials is governed by the oxidation-state variation of transition metal centers and achieved a charge balance with the insertion of counterions. [18] Restricted by crystal lattice and structure stability, the size and valence of counterions are required to match the crystal structures, which severely limit further improvement of energy density. [19][20][21] Clearly, these factors intrinsically weaken the versatility of inorganic materials. For instance, the similar electrode materials, which are successful in LIBs, are not suitable for other alkali ions batteries. [22][23][24] Additionally, from the viewpoint of economical and renewable factors of mineral resources, the existing LIBs based on transition metals (e.g., cobalt, nickel, and manganese) are difficult to meet the requirement of large-scale energy storage. [25] Nowadays, various demands have been raised up for the state-ofthe-art batteries, not only in the enhancement of cycle life, fast charging, and safety, but also in the focus of cost, lightweight, pollution-free, and environmental benign. [26,27] Under this background, researchers gradually shift their studies on novel batteries system and electrode materials. [28][29][30][31] Among them, explorations on the possibility of using organic compounds as potential alternatives of current inorganic electrode materials have never been stopped. [32,33,66] Organics have been demonstrated as promising electrode candidates due to their variety, sustainability, relatively low cost, and environmental friendliness. [34][35][36] The structural diversity implies that the richness of organic materials will provide abundant options and room in this field. The molecule engineering means that the electrochemical properties of organic electrodes can be rationally tuned with different functional groups, which exhibits a good designability of organic materials. These important features allow various designable synthetic routes and convenient functionalization. Although organic electrode materials are endowed with many advantages, their development and Covalent-organic frameworks (COFs), featuring structural diversity, framework tunability and functional versatility, have emerged as promising organic electrode materials for rechargeable batteries and garnered tremendous attention in recent years. The adjustable pore configuration, coupled with the functionalization of frameworks through ...

Here, we report a new Ti(IV)-based porous metal-organic framework (MOF) (NTU-9), which displayed strong absorption in the visible region with a bandgap of 1.72 eV. The electronic structure and bandgap were further investigated by DFT calculations. Photoelectrochemical studies indicated that NTU-9 is photoactive under visible light illumination (λ > 400 nm) and acts as a p-type semiconductor. The results demonstrated that Ti(IV)-based MOFs could be promising visible-light photocatalysts for energy conversion and environmental remediation.