Carbon nanotube- and graphene-based nanomaterials and applications in high-voltage supercapacitor: A review

Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid–base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.

Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

Methane decomposition to COx-free hydrogen and nano-carbon material on group 8–10 base metal catalysts: A review

Preparation and characterization of polyaniline/multi-walled carbon nanotube composites

Fast rechargeable batteries made from low-cost and abundant electrode materials are attractive for energy storage. Wang et al. develop an ultrafast Ni–Fe battery with carbon/inorganic hybrid electrodes in which the charge and discharge rates are nearly 1,000-fold higher than traditional Ni–Fe batteries.

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An ultrafast nickel–iron battery from strongly coupled inorganic nanoparticle/nanocarbon hybrid materials

Methane decomposition over a Ni/Cu/Al 2 O 3 catalyst is studied in a two-stage fluidized bed reactor. Low temperature is adopted in the lower stage and high temperature in the upper stage. This allows the fluidized catalysts to decompose methane with high activity in the high temperature condition; then the carbon produced will diffuse effectively to form carbon nanotubes (CNTs) in both low and high temperature regions. Thus the catalytic cycle of carbon production and carbon diffusion in micro scale can be tailored by a macroscopic method, which permits the catalyst to have high activity and high thermal stability even at 1123 K for hydrogen production for long times. Such controlled temperature condition also provides an increased thermal driving force for the nucleation of CNTs and hence favors the graphitization of CNTs, characterized by high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and XRD. Multistage operation with different temperatures in a fluidized bed reactor is an effective way to meet the both requirements of hydrogen production and preparation of CNTs with relatively perfect microstructures.

Production of hydrogen and carbon nanotubes from methane decomposition in a two-stage fluidized bed reactor

Carbon nanotubes (CNTs) prepared from ethylene decomposition over the Fe/Al 2 O 3 catalyst are studied in a packed bed (PB) reactor and a nanoagglomerate fluidized bed reactor (NABR), respectively. CNTs sampled at different reaction times are characterized by TEM, Raman spectroscopy, and particle size analysis. The bulk density and agglomerate size of CNTs increase significantly with reaction time in a PB, while it remains at a stable level in NABR. Also, CNTs with good morphology, narrow diameter distribution, and fewer lattice defects are obtained in an NABR, rather than in a PB. In contrast to the unavoidable jamming due to volume increase of CNTs observed in a PB, a continuous CNT growth process is attained in an NABR, even though the amount of CNTs in an NABR is 6-7 times that in a PB. The flow dynamics, available space for growing, and mass and heat transfer can be controlled in an NABR, which favors the large-scale production of CNTs with uniform properties.

Liu Tang

Papers

Production of hydrogen and carbon nanotubes from methane decomposition in a two-stage fluidized bed reactor

Production of carbon nanotubes in a packed bed and a fluidized bed