Magnetic Fe3O4-activated carbon nanocomposite was synthesized for the first time from rice husk based activated carbon. It was interesting to find the obtained composite still held a relatively large ...pore diameter of 3.1 nm, high surface area of 770 m2/g with 23 wt.% Fe3O4 coated, and a saturation magnetization (Ms) of 2.78 emu/g. The system demonstrated perfect magnetic separation performance and a high adsorption capacity of 321 mg/g for Methylene Blue (MB) from aqueous solution, both of which are significant for activated carbon’ s use as adsorbent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A simple approach was developed for the fabrication of a Fe2O3/carbon composite by impregnating activated carbon with a ferric nitrate solution and calcinating it. The composite contains graphitic ...layers and 10wt.% Fe2O3 particles of 20–50nm in diameter. The composite has a high specific surface area of ∼828m2g−1 and when used as the anode in a lithium ion battery (LIB), it showed a reversible capacity of 623mAhg−1 for the first 100 cycles at 50mAg−1. A discharge capacity higher than 450mAhg−1 at 1000mAg−1 was recorded in rate performance testing. This highly improved reversible capacity and rate performance is attributed to the combination of (i) the formation of graphitic layers in the composite, which possibly improves the matrix electrical conductivity, (ii) the interconnected porous channels whose diameters ranges from the macro- to meso- pore, which increases lithium-ion mobility, and (iii) the Fe2O3 nanoparticles that facilitate the transport of electrons and shorten the distance for Li+ diffusion. This study provides a cost-effective, highly efficient means to fabricate materials which combine conducting carbon with nanoparticles of metal or metal oxide for the development of a high-performance LIB.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The structural characteristics of natural species have been optimized by natural selection for millions of years. They offer specific functions much more effectively than artificial approaches. ...Morphology genetic materials utilize morphologies gleaned from natural selection into their hierarchical structures. The combination of natural morphologies and manually selected functional materials makes these novel materials suitable for many applications. This review focuses on the strategies by which the structures and functions of natural species can be utilized. Specific functions inherited from both the natural microstructures and coupled functional materials are highlighted with regard to various applications, including photonics, light‐harvesting, surface‐enhanced Raman scattering (SERS), and electrodes for supercapacitors and batteries, as well as environmentally friendly materials.
Morphology genetic materials utilize morphologies gleaned from biological structures into their hierarchical structures. This review shows the strategies by which the structures and functions of natural species can be utilized. Specific functions inherited from both natural microstructures and coupled functional materials are highlighted with regard to various applications, including light‐harvesting, surface‐enhanced Raman scattering (SERS), and electrodes for supercapacitors and batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The development of high-performance thermal management materials to dissipate excessive heat both in plane and through plane is of special interest to maintain efficient operation and prolong the ...life of electronic devices. Herein, we designed and constructed a graphene-based composite film, which contains chiral liquid crystals (cellulose nanocrystals, CNCs) inside graphene oxide (GO). The composite film was prepared by annealing and compacting of self-assembled GO-CNC, which contains chiral smectic liquid crystal structures. The helical arranged nanorods of carbonized CNC act as in-plane connections, which bridge neighboring graphene sheets. More interestingly, the chiral structures also act as through-plane connections, which bridge the upper and lower graphene layers. As a result, the graphene-based composite film shows extraordinary thermal conductivity, in both in-plane (1820.4 W m–1 K–1) and through-plane (4.596 W m–1 K–1) directions. As a thermal management material, the heat dissipation and transportation behaviors of the composite film were investigated using a self-heating system and the results showed that the real-time temperature of the heater covered with the film was 44.5 °C lower than a naked heater. The prepared film shows a much higher efficiency of heat transportation than the commonly used thermal conductive Cu foil. Additionally, this graphene-based composite film exhibits excellent mechanical strength of 31.6 MPa and an electrical conductivity of 667.4 S cm–1. The strategy reported here may open a new avenue to the development of high-performance thermal management films.
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IJS, KILJ, NUK, PNG, UL, UM
A high-efficiency electro-thermal heater requires simultaneously high electrical and thermal conductivities to generate and dissipate Joule heat efficiently. A low input voltage is essential to ...ensure the heater’s safe applications. However, the low voltage generally leads to low saturated temperature and heating rate and hence a low thermal efficiency. How to reduce the input voltage while maintaining a high electro-thermal efficiency is still a challenge. Herein, a highly electrical and thermal conductive film was constructed using a graphene-based composite which has an internal three-dimensional (3D) conductive network. In the 3D framework, cellulose nanocrystalline (CNC) phase with chiral liquid crystal manner presents in the form of aligned helix between the graphene oxide (GO) layers. Carbon nanodots (CDs) are assembled inside the composite as conductive nanofillers. Subsequent annealing and compression results in the formation of the assembled GO-CNC-CDs film. The carbonized CNC nanorods (CNR) with the helical alignment act as in-plane and through-plane connections of neighboring reduced GO (rGO) nanosheets, forming a conductive network in the composite film. The CDs with ultrafast electrons transfer rates provide additional electrons and phonons transport paths for the composite. As a result, the obtained graphene-based composite film (rGO-CNR-CDs) exhibited a high thermal conductivity of 1,978.6 W·m
−1
·K
−1
and electrical conductivity of 2,053.4 S·cm
−1
, respectively. The composite film showed an outstanding electro-thermal heating efficiency with the saturated temperature of 315 °C and maximum heating rate of 44.9 °C·s
−1
at a very low input voltage of 10 V. The freestanding graphene composite film with the delicate nanostructure design has a great potential to be integrated into electro-thermal devices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Previous studies on polymer/graphene composites have mainly utilized either reduced graphene oxide or graphite nanoplatelets of over 10nm in thickness. In this study we covalently modified 3-nm thick ...graphene platelets (GnPs) by the reaction between the GnPs’ epoxide groups and the end-amine groups of a commercial long-chain surfactant (Mw=2000), compounded the modified GnPs (m-GnPs) with a model polymer epoxy, and investigated the structure and properties of both m-GnPs and their epoxy composites. A low Raman ID/IG ratio of 0.13 was found for m-GnPs corresponding to high structural integrity. A percolation threshold of electrical conductivity was observed at 0.32vol% m-GnPs, and the 0.98vol% m-GnPs improved the Young’s modulus, fracture energy release rate and glass transition temperature of epoxy by 14%, 387% and 13%, respectively. These significantly improved properties are credited to: (i) the low Raman ID/IG ratio of GnPs, maximizing the structural integrity and thus conductivity, stiffness and strength inherited from its sister graphene, (ii) the low thickness of GnPs, minimizing the damaging effect of the poor through-plane mechanical properties and electrical conductivity of graphene, (iii) the high-molecular weight surfactant, leading to uniformly dispersed GnPs in the matrix, and (iv) a covalently bonded interface between m-GnPs and matrix, more effectively transferring load/electron across interface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► Fe3O4 nanoparticles are fabricated uniformly on the surface of reduced graphene oxide by a sonochemical method. ► The particle size of Fe3O4 are controlled at around 30–40nm. ► The resultant ...Fe3O4/RGO composite shows a high biosensor performance. ► RGO promotes the electron transfer between the peroxide and electrode surface.
This study synthesized Fe3O4 nanoparticles of 30–40nm by a sonochemical method, and these particles were uniformly dispersed on the reduced graphene oxide sheets (Fe3O4/RGO). The superparamagnetic property of Fe3O4/RGO was evidenced from a saturated magnetization of 30emu/g tested by a sample-vibrating magnetometer. Based on the testing results, we proposed a mechanism of ultrasonic waves to explain the formation and dispersion of Fe3O4 nanoparticles on RGO. A biosensor was fabricated by modifying a glassy carbon electrode with the combination of Fe3O4/RGO and hemoglobin. The biosensor showed an excellent electrocatalytic reduction toward H2O2 at a wide, linear range from 4×10−6 to 1×10−3M (R2=0.994) as examined by amperometry, and with a detection limit of 2×10−6M. The high performance of H2O2 detection is attributed to the synergistic effect of the combination of Fe3O4 nanoparticles and RGO, promoting the electron transfer between the peroxide and electrode surface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We report a novel method for the preparation of graphitic carbon nitride (g‐C3N4) with various morphologies through self‐assembly and calcination, which starts from the raw materials melamine, urea, ...and cyanuric acid. The hollow to wormlike morphologies of g‐C3N4 could be readily tailored by adjusting the molar ratio of melamine to urea; with increase in the molar ratio from 3:1 to 1:3, a morphology transformation was observed. The morphologies were tailored by self‐assembly of the aggregates by hydrogen bonding and ionic interactions. Correspondingly, an increased BET surface area from 49.6 to 97.4 m2 g−1 was observed. If used as a photocatalyst in degrading rhodamine B (RhB) under visible‐light irradiation, these g‐C3N4 samples demonstrated 7 to 13 times higher performance than conventional bulk g‐C3N4. The high performance was attributed to the unique morphology that provided not only high specific surface area but low recombination losses of photogenerated charges.
Shaping graphitic nitrides: Synthesis of graphitic carbon nitride (g‐C3N4) and tailoring of its morphology was performed through adjustment of the molar ratio of melamine to urea, their self‐assembly by hydrogen bonding and ionic interactions, and calcination.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Graphene platelets (GnPs) are a class of novel 2D nanomaterials owing to their very small thickness ( 3 nm), high mechanical strength and electric conductivity (1460 S cm−1), and good compatibility ...with most polymers as well as cost-effectiveness. In this paper we present a low-cost processing technique for producing modified GnPs and an investigation of the electrical and mechanical properties of the resulting composites. After dispersing GnPs in solvent N-methyl-2-pyrrolidone, a long-chain surfactant (Jeffamine D 2000, denoted J2000) was added to covalently modify GnPs, yielding J2000-GnPs. By adjusting the ratio of GnPs to the solvent, the modified GnPs show different average thickness and thus electrical conductivity ranging from 694 to 1200 S cm−1. To promote the exfoliation and dispersion of J2000-GnPs in a polymeric matrix, they were dispersed in the solvent again and further modified using diglycidyl ether of bisphenol A (DGEBA) producing m-GnPs, which were then compounded with an epoxy resin for the development of epoxy/m-GnP composites. A percolation threshold of electrical volume resistivity for the resulting composites was observed at 0.31 vol%. It was found that epoxy/m-GnP composites demonstrated far better mechanical properties than those of unmodified GnPs of the same volume fraction. For example, m-GnPs at 0.25 vol% increased the fracture energy release rate G1c from 0.204 ± 0.03 to 1.422 ± 0.24 kJ m−2, while the same fraction of unmodified GnPs increased G1c to 1.01 ± 0.24 kJ m−2. The interface modification also enhanced the glass transition temperature of neat epoxy from 58.9 to 73.8 °C.
Porous graphitic carbons encapsulating Fe nanoparticles (PGCFs) were fabricated by infiltrating activated carbon (AC) with an iron salt and thereafter heat-treating the products in vacuum, and the ...electromagnetic parameters of the PGCF were investigated over 2–18GHz frequency. The results demonstrated that the formation of porous graphitic network encapsulating Fe nanoparticles endowed the composite a very high permittivity and dielectric loss at 2–18GHz. Return loss (RL) for the PGCF-based absorbers were investigated based on the measured electromagnetic parameters. A typical dual-layer absorber exhibited an excellent microwave absorption with a 43dB maximum absorption at 10GHz and a nearly 7GHz bandwidth for RL<−20dB.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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