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The self-restacking of graphene nanosheets inevitably compromises the electrochemical performance of conventional graphene-based materials. Herein, to solve this problem, we prepared a new type of three-dimensional porous aerogel with partially unzipped multiwalled carbon nanotubes inserted into graphene nanosheets via a reduction-reaction-induced self-assembly process. In the resulting aerogels, the inner carbon nanotubes (CNTs) tightly attach to the unzipped outer graphene nanoribbons (GNRs), which bridge with the graphene nanosheets. These interconnections bring them excellent electrical contact; the CNTs act as spacers to prevent the restacking of adjacent graphene nanosheets, and the abundant interconnected pores in the aerogels provide large channels for charge transfer. Accordingly, the aerogels exhibit a specific capacitance of 348.4 Fg−1 at a scan rate of 5 mVs−1, with capacitance retention remaining at 89.7% at a current density of 2 Ag−1 after 5000 cycles. The results show that the aerogels are promising electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In this study, a novel low-Pt core-shell catalyst is successfully prepared by depositing ultrathin Pt layer on the carbon nanotubes supported titanium nitride nanoparticles (TiN@Pt/CNTs) via a facile pulse electrochemical deposition approach. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), High-angle annular dark field (HAADF) and energy-dispersive spectrometer (EDS) elemental mapping, X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The results confirm the core-shell structure of the prepared TiN@Pt/CNTs catalyst. More importantly, the catalyst exhibits superb mass activity and durability for the methanol oxidation reaction (MOR) than that of the commercial JM Pt/C catalyst. Later experiments data demonstrate that the activity and stability of the catalyst can be further enhanced via copper doping, which results from the modified electronic structure of the Pt atoms and the synergistic effects of the core-shell structure. [ABSTRACT FROM AUTHOR]

Polyol approach is commonly used in synthesizing Pt nanoparticles in polymer electrolyte membrane fuel cells. However, the application of this process consumes a great deal of time and energy, as the reduction of precursors requires elevated temperatures and several hours. Moreover, the ethylene glycol and its oxidizing products bound to Pt are difficult to remove. In this work, we utilize the advantages of ethylene glycol and prepare Pt nanoparticles through a room-temperature hydrogen gas reduction in an ethylene glycol/water mixed solvent, which is followed by subsequent harvesting by carbon nanotubes as electrocatalysts. This method is simple, facile, and time-efficient, as the entire room-temperature reduction process is completed in a few minutes. As the solvent changes from water to an ethylene glycol/water mix, the size of Pt nanoparticles varies from 10 to 3 nm and their shape transitions from polyhedral to spherical. Pt nanoparticles prepared in a 1:1 volume ratio mixture of ethylene glycol/water are uniformly dispersed with an average size of ∼3 nm. The optimized carbon nanotube-supported Pt electrocatalyst exhibits excellent methanol oxidation and oxygen reduction activities. This work demonstrates the potential use of mixed solvents as an approach in materials synthesis. [ABSTRACT FROM AUTHOR]

In this article, a facile one-step strategy for the synthesis of ternary MnO 2 –Fe 2 O 3 –CeO 2 –Ce 2 O 3 /carbon nanotubes (CNT) catalysts was discussed. The as-prepared catalysts exhibited 73.6–99.4% NO conversion at 120–180 °C at a weight hourly space velocity (WHSV) of 210 000 ml·g cat − 1 ·h − 1 , which benefited from the formation of amorphous MnO 2 , Fe 2 O 3 , CeO 2 , and Ce 2 O 3 , as well as high Ce 3 + and surface oxygen (O ε ) contents. The mechanism of formation of MnO 2 –Fe 2 O 3 –CeO 2 –Ce 2 O 3 /CNT catalysts was also proposed. [ABSTRACT FROM AUTHOR]

A novel redox co-precipitation method was firstly adopted to prepare the Mn–FeO x /CNTs catalysts for use in low-temperature NO reduction with NH 3 . The catalysts were possessed of amorphous structure and exhibited 80–100% NO conversion at 140–180 °C at a high space velocity of 32,000 h − 1 . [ABSTRACT FROM AUTHOR]

The self-restacking of graphene nanosheets inevitably compromises the electrochemical performance of conventional graphene-based materials. Herein, to solve this problem, we prepared a new type of three-dimensional porous aerogel with partially unzipped multiwalled carbon nanotubes inserted into graphene nanosheets via a reduction-reaction-induced self-assembly process. In the resulting aerogels, the inner carbon nanotubes (CNTs) tightly attach to the unzipped outer graphene nanoribbons (GNRs), which bridge with the graphene nanosheets. These interconnections bring them excellent electrical contact; the CNTs act as spacers to prevent the restacking of adjacent graphene nanosheets, and the abundant interconnected pores in the aerogels provide large channels for charge transfer. Accordingly, the aerogels exhibit a specific capacitance of 348.4 Fg−1 at a scan rate of 5 mVs−1, with capacitance retention remaining at 89.7% at a current density of 2 Ag−1 after 5000 cycles. The results show that the aerogels are promising electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) supported manganese oxide catalysts were prepared through different thermal treatment routes and used for low-temperature selective catalytic reduction of NO with NH3. The MnOx/CNTs catalyst prepared by calcined the precursor in air at 300°C showed lower NO conversions than that treated at 250°C, while it showed higher NO conversions than the one calcined in nitrogen. BET, TGA, XRD and H2-TPR results indicated that CNTs may impose effects on the oxidation state and redox ability of the manganese oxide and hence on the catalytic activity during the calcination process at given temperatures. [ABSTRACT FROM AUTHOR]

Abstract: A series of Mn–Ce mixed-oxide catalysts supported on carbon nanotubes (CNTs) were prepared for the first time and used for the selective catalytic reduction of NO with NH3. Mn(0.4)-Ce/CNTs catalysts with loading from 0.6% to 1.8% (molar ratio) in our tests showed more than 90% NO conversion at 120–180°C at a high space velocity of 42,000h−1. Transmission electron microscopy confirmed that the particle size of Mn–Ce mixed oxides supported on CNTs was 2 to 4nm. BET result indicated Mn–Ce mixed-oxide catalysts obtained enlarged surface area and pore volume which was beneficial to the catalytic activity. [Copyright &y& Elsevier]

Abstract: Poly(3-acetylpyrrole) (PAPy)/multi-walled carbon nanotubes (MWNTs) composites are fabricated by in situ chemical polymeriation of 3-acetylpyrrole (APy) on MWNTs. The electrical and electrochemical properties of the resulting composites are investigated using a four-probe method, and cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques, respectively. The electrical conductivity and specific capacitance of the composites are 1.64Scm−1 and 65Fg−1 (APy:MWNTs=2.5:1), and 0.35Scm−1 and 53Fg−1 (APy:MWNTs=5:1), respectively. In addition, the effect of the feed ratio of APy to MWNTs is also discussed in detail. [Copyright &y& Elsevier]

Monomer casting polyamide 6(MCPA6)/toluene 2,4-diisocyanate functionalized multi-walled carbon nanotubes (MWNTs-NCO) nanocomposites were prepared via in situ anionic ring opening polymerization, and the non-isothermal crystallization behavior of the nanocomposites were investigated by differential scanning calorimetry with various cooling rates. The commonly used Avrami, Ozawa, Mo, and Urbanovici-Segal models were employed to analyze the non-isothermal crystallization data and the validity of the models on the process of MCPA6 and its nanocomposites was discussed, where Mo and Urbanovici-Segal models could well describe the non-isothermal crystallization process for the samples. The results revealed that MWNTs could accelerate the crystallization process of MCPA6, attributing to the nucleating effect of the nanofillers. Finally, the effective energy barrier for non-isothermal crystallization was evaluated as a function of the relative crystallinity by applying an isoconversional method. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen-doped carbon nanotube (N-CNT) arrays were prepared by chemical vapor deposition, using ferrocene as the catalyst precursor and imidazole as the carbon and nitrogen precursor. For the reduction of oxygen, the N-CNTs showed excellent electrocatalytic activity in both acidic and alkaline media. The N-CNTs were characterized by scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and elemental analysis. The samples had a high nitrogen content (8.54at.%) and a bamboo-like structure, and their activity varied according to the amount of pyridinic nitrogen they contained. [Copyright &y& Elsevier]

-x/carbon nanotubes (CNTs) catalysts were firstly prepared via simple incipient wetness method and used for low-temperature selective catalytic reduction (SCR) of with 3. The structure and surface properties of the catalysts were characterized by 2 sorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen (2-TPR). It was found that -x/CNTs catalyst exhibited excellent low-temperature SCR activity and 2 resistance. XRD patterns revealed that metal oxides catalysts were possessed of amorphous structure. FESEM and TEM images showed that metal oxides catalysts were successfully supported on CNTs. The XPS results indicated that the obtained catalyst presented high 4+/3+ and OS/(OS + OL) ratios. The 2-TPR profiles showed that -x/CNTs catalyst possessed better low-temperature reducibility. Besides, the obtained catalyst exhibited better 2 resistance. Highly active Mn-FeOx/CNTs catalysts were first synthesized by incipient wetness method and applied in low-temperature NO reduction with NH3. The as-obtained catalysts showed excellent low-temperature SCR activity. Thereinto, the 1.2% Mn-FeOx/CNTs catalyst presented the first-rate catalytic activity at 80-180°C, which benefited from its amorphous phase, high Mn4+/Mn3+ and OS/(OS+OL) ratios. [ABSTRACT FROM AUTHOR]