Recent Advances on Carbon Nanotubes and Graphene Reinforced Ceramics Nanocomposites

Open Access articleCeramics suffer the curse of extreme brittleness and demand new design philosophies and novel concepts of manufacturing to overcome such intrinsic drawbacks, in order to take advantage of most of their excellent properties. This has been one of the foremost challenges for ceramic material experts. Tailoring the ceramics structures at nanometre level has been a leading research frontier; whilst upgrading via reinforcing ceramic matrices with nanomaterials including the latest carbon nanotubes (CNTs) and graphene has now become an eminent practice for advanced applications. Most recently, several new strategies have indeed improved the properties of the ceramics/CNT nanocomposites, such as by tuning with dopants, new dispersions routes and modified sintering methods. The utilisation of graphene in ceramic nanocomposites, either as a solo reinforcement or as a hybrid with CNTs, is the newest development. This article will summarise the recent advances, key difficulties and potential applications of the ceramics nanocomposites reinforced with CNTs and graphene.Research Center of College of Engineering, Deanship of Scientific Research, King Saud University, Riyadh, Kingdom of Saudi Arabi

Three-dimensional carbon foam nanocomposites for thermal energy storage

Nanocomposites consisting of paraffin/graphene nanoplatelets mix embedded in carbon foams via vacuum infiltration were fabricated with the aim of developing new phase change material (PCM) formulation with excellent shape stabilization, improved thermal conductivity and outstanding thermal reliability and structural stability. Physicochemical and thermal properties of the nanocomposites were evaluated using a suite of techniques such as scanning and transmission electron microscopy, X-ray diffraction, attenuated total reflection - Fourier transform infrared spectroscopy, nitrogen adsorption analyzer, differential scanning calorimetry, mechanical tester, Raman spectroscopy, thermal conductivity analyzer and thermogravimetric analyzer. The carbon foams exhibited good cyclic compressive behavior at a strain of up to 95% and kept part of their elastic properties after cyclic testing. Due to the robust mechanical integrity and layered meso-/macroporous morphology of these carbon foams, the nanocomposites are well equipped to cope with volume changes without leaking during thermal cycling. A 141% thermal conductivity enhancement observed for the carbon foam nanocomposite demonstrates the contributing role of the carbon foam in creating effective heat transfer through its conductive 3D network. The results have shown that proper chemical modification and subsequent carbonization of the low cost porous foams can lead to ultralight multifunctional materials with high mechanical and physical properties suitable for thermal energy storage applications

A highly efficient and versatile carbon nanotube/ceramic composite filter

Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Carbon. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Carbon Vol. 54 (2013), DOI: 10.1016/j.carbon.2012.11.032Carbon nanotubes were grown in the open pores of a commercial porous ceramic matrix consisting of mainly Al2O3 and SiO 2 with an average pore size of 300 and 500 μm, using a pre-formed nickel catalyst inside the pores and a camphor solution precursor at 780 °C. The resulting composites, ∅27 mm × 10 mm discs containing about 3 wt.% of carbon nanotubes, were then assessed as a filter for the removal of yeast cells and different heavy metal ions from water, and for the removal of particulates from air. The results showed that the carbon nanotube containing composite filter demonstrated a high efficiency of yeast filtration (98%), ca. 100% heavy metal ion removal from water and excellent particulate filtration from air. The composite filter also exhibited good reusability for these applications, owing to the excellent thermal and chemical stability of the carbon nanotubes. © 2012 Elsevier Ltd. All rights reserved.Engineering and Physical Sciences Research Council (EPSRC

In situ fabrication of dendritic tin-based carbon nanostructures for hydrogen evolution reaction

In this work, dendritic tin-based carbon (Sn/C) nanostructures with four different morphologies were synthesized by a facile two-step carbonization and chemical vapor deposition method and were then evaluated for their performance in hydrogen evolution reaction. The Sn/C dendrites are approximately 0.5 – 4.5 µm in length, each having secondary branches in different directions. The four morphologies of the Sn/C dendrites namely nanoflowers (Sn_NCF1), nanospheres (Sn_NCF2), nanocubes (Sn_NCF3) and nanocuboids (Sn_NCF4), behave differently in their electrochemical performance, with Sn_NCF2 and Sn_NCF1 performing better. Sn_NCF2 demonstrates optimal HER performance compared to other Sn based samples with onset potential and overpotential of 100 and 260 mV, respectively. The higher electrochemical surface area observed in Sn_NCF2 was originated from the presence of more catalytic sites which contributed to the enhanced HER activity and better current density, against other Sn-based samples. In addition to the improved HER performance, Sn_NCF2 demonstrates excellent stability with less than 6% degradation of its initial current after operating for over 8 h in acidic media

Atomically homogeneous dispersed ZnO/N-doped nanoporous carbon composites with enhanced CO2 uptake capacities and high efficient organic pollutants removal from water

Author's manuscript version. The final published version is available from the publisher via doi:10.1016/j.carbon.2015.08.015Copyright © 2015 Elsevier Ltd. All rights reserved.Article first available online - 8th August 2015Advanced functional composite of ZnO nanoparticles embedded in N-doped nanoporous carbons has been synthesized by a simple one-step carbonization of zeolitic imidazolate framework-8 under a water stream atmosphere. A variety of characterization techniques show that the introduction of water steam during the carbonization process holds the key to obtain the fine and homogeneously dispersed ZnO nanoparticles within the functionalised nanoporous carbon matrix. Possessing a higher specific surface area, a larger pore volume and abundant oxygen-containing hydrophilic functional groups, the resulting composite exhibits a stronger interaction with CO2 and is more efficient to promote the photocatalytic degradation-adsorption of methylene blue under visible light than the composite obtained without steam treatment. As a result, the steam derived composite exhibits increased CO2 uptake capacity and excellent methylene blue molecules removal from water. Using different metal-organic frameworks as precursors, this new, simple and green method can be further expanded to generate various new homogeneous dispersed functional metal oxide/porous carbon composites with high efficiency in relevant applications. © 2015 Elsevier Ltd.Royal SocietyRoyal Academy of Engineerin

Carbon nanotube reinforced nanocomposites for energy conversion and storage

CNT-reinforced foams comprised of three-dimensional (3D) interconnected macropores with uniform mesoporous walls were developed as multifunctional nanocomposites and tested for electrochemical energy conversion and storage. Multi-walled CNTs grown on the wall surface of the interconnected scaffold structure of carbon foams were found to improve the surface area and electrochemical properties of the nanocomposites. The lightweight CNT-reinforced nanocomposites not only exhibit high structural flexibility, but also possess enhanced electrocatalytic performance for HER at current density of 10 mA cm−2 with overpotentials of 240 mV. In addition, these nanocomposites can be used as flexible, electric double layer capacitor electrodes, and have achieved a specific capacitance of 776 F g−1, with excellent durability and stability after 1000 cycles

In situ investigations of the phase change behaviour of tungsten oxide nanostructures

This study appraises the use of in-situ diffraction and spectroscopy techniques, complemented with ex-situ electron microscopy analyses, to investigate the geometry and phase change behaviour of bundled ultrathin W18O49 nanowires and WO3 nanoparticles. Our in-situ X-ray diffraction (XRD) results have shown that the phase transition of WO3 nanoparticles occurs in sequence as the temperature increases, from monoclinic (room temperature) → orthorhombic (350 ºC) → tetragonal (800 °C), akin to bulk WO3; however, W18O49 nanowires remain stable as the monoclinic phase up to 500 °C, after which complete oxidation to WO3 and transformation to the orthorhombic β-phase at 550 °C is observed. The in-situ Raman spectroscopy investigations have shown that as the temperature increases, the Raman peaks downshift toward lower wavenumbers in both structures, which can be attributed to the increased bond lengths in the lattice. We have also demonstrated that the Raman shift at 187.6 cm-1 can be used as a fingerprint band for the phase transition from the γ- to the β-phase of the WO3 nanoparticle. Furthermore, WO3 nanoparticles exhibit the γ- to β-phase conversion at 275 °C, which is about 75 °C lower than the relaxation temperature of 350 °C for the monoclinic γ-W18O49 nanowires. We propose that this fundamental phase transition understanding can offer important guidance for the design and development of WOx-based nanodevices by defining their allowed operating conditions

Cobalt sulfide/N,S codoped porous carbon core-shell nanocomposites as superior bifunctional electrocatalysts for oxygen reduction and evolution reactions.

Author's postprint version. The final published version is available via doi: 10.1039/C5NR07429KAccepted for publication 11 November 2015© Royal Society of Chemistry 2015Exploring highly-efficient and low-cost bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reactions (OER) in the renewable energy area has gained momentum but still remains a significant challenge. Here we present a simple but efficient method that utilizes ZIF-67 as the precursor and template for the one-step generation of homogeneous dispersed cobalt sulfide/N,S-codoped porous carbon nanocomposites as high-performance electrocatalysts. Due to the favourable molecular-like structural features and uniform dispersed active sites in the precursor, the resulting nanocomposites, possessing a unique core-shell structure, high porosity, homogeneous dispersion of active components together with N and S-doping effects, not only show excellent electrocatalytic activity towards ORR with the high onset potential (around -0.04 V vs.-0.02 V for the benchmark Pt/C catalyst) and four-electron pathway and OER with a small overpotential of 0.47 V for 10 mA cm(-2) current density, but also exhibit superior stability (92%) to the commercial Pt/C catalyst (74%) in ORR and promising OER stability (80%) with good methanol tolerance. Our findings suggest that the transition metal sulfide-porous carbon nanocomposites derived from the one-step simultaneous sulfurization and carbonization of zeolitic imidazolate frameworks are excellent alternative bifunctional electrocatalysts towards ORR and OER in the next generation of energy storage and conversion technologies.Royal SocietyRoyal Academy of Engineerin