The effect of an Al underlayer on Fe–Si thin film catalysts for the improved growth of carbon nanotubes

Wu, Wan-Yu; Teng, Fei; Ting, Jyh‐Ming

doi:10.1016/j.carbon.2011.06.079

Cited by 4 publications

(2 citation statements)

References 20 publications

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“…It was reported that the thickness of the Al layer could be responsible for controlling the length of CNTs. [27][28][29][30] The impact was mainly attributed to the diffusion of Al into the catalyst layer leading to a decrease in the carbon solubility in the catalyst particles. As shown in the literature, the decrease in the carbon solubility resulted in shorter CNTs as the Al layer thickness increases.…”

Section: Resultsmentioning

confidence: 99%

Simultaneous growth of self-patterned carbon nanotube forests with dual height scales

et al. 2012

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In this study, we report on a unique, one-step fabrication technique enabling the simultaneous synthesis of vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with dual height scales through alcohol catalyzed chemical vapor deposition (ACCVD). Regions of VA-MWCNTs with different heights were well separated from each other leading to a self-patterning on the surface. We devised a unique layer-by-layer process for application of catalyst and inhibitor precursors on oxidized Si (100) surfaces before the ACCVD step to achieve a hierarchical arrangement. Patterning could be controlled by adjusting the molarity and application sequence of precursors. Contact angle measurements on these self-patterned surfaces indicated that manipulation of these hierarchical arrays resulted in a wide range of hydrophobic behavior changing from that of a sticky rose petal to a lotus leaf.Inspired by the self-cleaning effect of lotus leaves, researchers have paid increasing attention to the generation of superhydrophobic surfaces having hierarchical structures with features ranging from micro-to nanoscale. The lotus leaf has a highly textured surface with protruding nubs (20-40 mm) which are further covered with nanometre sized wax crystals.1 Lotus leaf-like surfaces can be created either by covering a rough surface with a low surface energy material or by roughening/ etching/patterning the surface of a hydrophobic material. 10,11Functionalized vertically aligned multi-walled carbon nanotube (VA-MWCNT) arrays synthesized by CVD have also demonstrated superhydrophobic properties. 9,12Moreover, combining the CVD technique with photolithography for generating patterned carbon nanotube (CNT) arrays on surfaces has also been shown to improve and tailor superhydrophobicity of these surfaces.13 However, additional steps such as patterning with lithography for creating complex structures to improve hydrophobic behavior or imparting self-cleaning properties are not often cost efficient. Therefore, a simple, one-step production technique is required for the generation of artificial lotus leaf-like surfaces.Hence, the aim of this study is to imitate lotus leaf structures by creating dual-scale micro/nanostructures of aligned and patterned CNTs during the growth. For this purpose, we developed a unique technique based on the layer-by-layer application of catalyst and inhibitor precursors which is normally used to grow VA-MWCNTs by our group.14 By tuning the molarity, types, sequence and number of precursor and catalyst layers, we were able to not only generate hierarchical and patterned superhydrophobic VA-MWCNT arrays but also tailor the wettability properties. The resultant hierarchical structures were fully characterized (contact angle, surface topography, physical properties, and geometry) in order to identify the contribution of micro-and nano-structured aspects on water repellency. These hierarchical CNT arrays with micro-and nanoscales can be further developed to potentially find applications as self-cleaning dry-adhesives (gecko ...

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Section: Resultsmentioning

confidence: 99%

Simultaneous growth of self-patterned carbon nanotube forests with dual height scales

et al. 2012

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“…In some cases, metallic silicide can be generated between the catalysts and the Si substrate [51,52], which can increase the adhesion. However, these interactions will cause deterioration of the catalysts and typical solution is to add buffer layers, such as SiO 2 , Ti, Al [53]. Gohier et al [54] have indicated that the growth modes are determined by the size of the catalyst particles, which is related to the thickness of the catalyst film and they can cause a transition from the base growth few-wall CNTs to the tip growth multi-wall CNTs [33].…”

Section: Cost-effective In-situ Preparation Of Catalyst Filmmentioning

confidence: 99%

A novel hybrid method combining ASP with PECVD for in - situ low temperature synthesis of vertically aligned carbon nanotube films

Zhang²,

et al. 2017

Diamond and Related Materials

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In this study, an in-situ low temperature method to cost-effectively grow vertically aligned carbon nanotube (VACNT) films has been developed by combining advanced active screen plasma (ASP) technique with plasma enhanced chemical vapour deposition (PECVD). A novel active screen consisting of 316 stainless steel cylinder with double top lids was designed for the in-situ low-cost high-efficient preparation of catalyst films within a PECVD device, and VACNT films were grown from the catalyst films subsequently at low temperatures (≤ 500ºC). The deposited catalyst films and the VACNT films were characterised by SEM, AFM, XRD, Raman and TEM/EDS. The results show that the catalyst films consist of stainless steel nanoparticles with sizes around 50 nm. The growth of the CNTs is related to the PECVD temperature and the density of the CNTs is determined by the status of the catalyst films. The CNTs are multiwalled with nanoparticles at their tips. The mechanisms behind the in-situ low temperature synthesis are discussed based on the plasma physics, growth parameters and physical status of the catalyst films.

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Carbon nanotube growth at 420°C using nickel/carbon composite thin films as catalyst supports

Achour

Mel

Bouts

et al. 2013

Diamond and Related Materials

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The effect of an Al underlayer on Fe–Si thin film catalysts for the improved growth of carbon nanotubes

Cited by 4 publications

References 20 publications

Simultaneous growth of self-patterned carbon nanotube forests with dual height scales

Simultaneous growth of self-patterned carbon nanotube forests with dual height scales

A novel hybrid method combining ASP with PECVD for in - situ low temperature synthesis of vertically aligned carbon nanotube films

Carbon nanotube growth at 420°C using nickel/carbon composite thin films as catalyst supports

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