Characterization of Nanocarbons Produced by CVD of Ethylene in Alumina or Alumino‐Silicate Matrices

Abstract

In the last years, nanocarbons [1] such as microporous carbons and carbon nanotubes (CNT), [2] have attracted great attention mainly because of their well-tailored structure and texture and their structural, mechanical and electronic properties.Synthesis of nanocarbons can be performed by chemical vapor deposition (CVD) of hydrocarbons. CVD processes carried out in the presence of supported metals as catalysts have been studied in the production of carbon nanotubes, [3,4] because of lower growth temperature (below 1000 C) compared to arc-discharge or laser vaporization methods. Different supported transition metal catalysts have been used to typically produce an envelope of CNTs, that could contain metal particles inside. Recently, CVD performed in the presence of inorganic structure-directed or templated structure has been utilized to synthesize a wide variety of new carbon materials. During templated synthesis, substrate or precursor materials are included into the template framework in such a way that their final structure reflects shape and dimension of the template. Organic templates are commonly used to synthesize inorganic materials. For example, surfactants have been used to template the synthesis of MCM-41, [5] or other porous silicates [6,7] and oxides. [8] The use of microporous zeolites such as Y, ZSM-5, mordenite, L and more recently beta (BEA) as templates, [9,10] has been investigated to produce carbon materials with a controlled microporosity. Moreover, zeolites, such as Y, ZSM-5, BEA, used as supports of transition metal catalyst, [11±14] permit to produce carbon nanotubes by catalytic decomposition of different hydrocarbons. In these COMMUNICATIONS 804

Modelling of multiwall carbon nanotube transmission lines

“…The same trend is obtained in Fig.3 where the calculations of Fig.2(b) are repeated for a shorter MWCNT (l = 25 m) and assuming r = 4.2 in order to account for the presence of an alumina membrane [11]. The effects of the increased permittivity are to reduce the amplitude of Z in and to move resonances to lower frequency values.…”

“…The model applies to MWCNTs that are typically grown inside alumina templates [11] for possible application as future nanointerconnects.…”

Review on Synthesis Methods of Carbon Nanotubes as Activated Carbon Composites Based on Biomass for Supercapacitors in Electric Vehicles

“…[123] In the CVD method, the synthesis of CNTs uses a metal catalyst to destroy the carbon source molecules. [124][125][126][127] Arc discharge and laser vaporization methods can be categorized as methods that require high temperatures (>3000 K) and the reaction occurs quickly, while CVD occurs at medium temperatures (700-1473 K) and the reaction lasts long (from minutes to hours). In arc discharge and laser vaporization methods, CNTs are produced separately.…”

Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

“…To compare the effect of the operating conditions on the carbon structure order, thermogravimetric analyses [11][12][13] were performed on the samples reported in table 1. In fact, a different thermal behaviour, as shown by TG-DTG analysis, could contribute to characterize the carbon material present inside the pores with respect to its nature and structural order.…”

“…Carbon nanotubes were synthesized by chemical vapour deposition (CVD) of ethylene within the pores of both RAAO and CAAO membranes. Hydrocarbon pyrolysis was carried out in a laboratory apparatus consisting of a continuous flow microreactor, fed by an ethylene-nitrogen gas mixture [11,12]. For each gas a mass flow controller (MFC) was used in order to ensure a constant and controlled flow rate.…”