Influence of synthesis parameters on CCVD growth of vertically aligned carbon nanotubes over aluminum substrate

Anna Szabó,Tamás Gyulavári,Endre Horvath,Egon Kecsenovity,Krisztián Németh,Zsuzsanna Pápa,Klara Hernadi

doi:10.1038/s41598-017-10055-0

Anna Szabó, Tamás Gyulavári + Show 5 more

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https://doi.org/10.1038/s41598-017-10055-0

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Journal: Scientific Reports	Publication Date: Aug 25, 2017
Citations: 28	License type: open-access

Affiliation: University of Szeged

Abstract

In the past two decades, important results have been achieved in the field of carbon nanotube (CNT) research, which revealed that carbon nanotubes have extremely good electrical and mechanical properties The range of applications widens more, if CNTs form a forest-like, vertically aligned structure (VACNT) Although, VACNT-conductive substrate structure could be very advantageous for various applications, to produce proper system without barrier films i.e. with good electrical contact is still a challenge. The aim of the current work is to develop a cheap and easy method for growing carbon nanotubes forests on conductive substrate with the CCVD (Catalytic Chemical Vapor Deposition) technique at 640 °C. The applied catalyst contained Fe and Co and was deposited via dip coating onto an aluminum substrate. In order to control the height of CNT forest several parameters were varied during the both catalyst layer fabrication (e.g. ink concentration, ink composition, dipping speed) and the CCVD synthesis (e.g. gas feeds, reaction time). As-prepared CNT forests were investigated with various methods such as scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry. With such an easy process it was possible to tune both the height and the quality of carbon nanotube forests.

Highlights

Aligned carbon nanotubes (VACNTs) denoted as carbon nanotube forests (CNT forest) were first synthesized in 19961, and subsequently they got into the focus of research in nanotechnology
A cheap and easy method was presented for the production of Vertically aligned carbon nanotubes (VACNTs) onto conductive substrate
It was shown that CNT forest height grown onto an Al plate during chemical vapor deposition (CCVD) synthesis can be controlled by numerous parameters

Summary

Introduction

Aligned carbon nanotubes (VACNTs) denoted as carbon nanotube forests (CNT forest) were first synthesized in 19961, and subsequently they got into the focus of research in nanotechnology. Catalytic chemical vapor deposition (CCVD) proved to be the most efficient way for the production of vertically aligned CNTs. The most common and efficient catalysts are the mono- or bimetallic transition metals (Fe, Co, Ni), while Al2O3, SiO2 or MgO are generally applied as supports[2,3,4,5,6]. The CVD parameters (such as carbon source, gas feed, reaction time, reaction temperature, etc.) have significant role in the formation of VACNTs. Iijima et al have investigated the kinetics of water-assisted CVD by a quantitative time-evolution analysis and concluded that the complex behavior of the time evolution of supergrowth can be explained by analyzing the two fitting parameters of the simple growth model, i.e. initial growth rate and the characteristic catalyst lifetime[10]. From the perspective of the catalyst, the thickness, composition, density and adherence of the transition metal layer are crucial parameters and have major effect on the properties of CNT growth. In 2003 it was already pointed out that high-quality but not aligned SWNTs can be synthesized directly onto silicon and quartz substrates using the easy and costless dip-coating approach for the deposition of catalytic metals[24]

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