Graphene nanosheet-grafted double-walled carbon nanotube hybrid nanostructures by two-step chemical vapor deposition and their application for ethanol detection

Worawut Muangrat,Winadda Wongwiriyapan,Yoshio Hashimoto,Shingo Morimoto

doi:10.1038/s41598-019-44315-y

Worawut Muangrat, Winadda Wongwiriyapan + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-44315-y

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Abstract

Here, we present a facile technique for synthesis of graphene nanosheet (GNS)-grafted double-walled carbon nanotube (DWCNT) hybrid carbon nanostructures (here after referred to as G-DWCNTs) by directly growing GNSs along the sidewalls of DWCNTs using a two-step chemical vapor deposition (CVD). DWCNTs were synthesized by floating catalyst CVD at 1300 °C using ferrocene and thiophene dissolved in ethanol. Then, GNSs were grafted onto the synthesized DWCNT bundles by thermal CVD at 1300 °C using ethanol. The sharp-edged petal-like structure of GNSs were grown along the sidewalls of DWCNT bundles while maintaining the one-dimensional structure of DWCNT. Next, DWCNTs and G-DWCNTs were dispersed in ethanol, then deposited on the paper using vacuum filtration method and used for ethanol detection. G-DWCNTs sensor exhibited a 3-fold improvement in the response to ethanol vapor compared to the DWCNTs sensor. The sensing mechanism of DWCNTs and G-DWCNTs can be described in terms of charge transfer between the gas molecules and sensing material. These results demonstrate that the facile technique by two-step CVD method provides a promising approach for simple and low-cost technique to synthesize the hybrid nanostructure of GNSs and DWCNTs. The new hybrid carbon nanostructures are attractive for gas sensing application.

Highlights

Graphene[1,2] and carbon nanotubes (CNTs)[3,4] are attractive materials in low-dimensional carbon allotropes which have been received widespread attention due to their unique structure and fascinating properties, such as mechanical[5,6,7], electrical[8,9], and thermal properties[5,6,10]
After graphene nanosheet (GNS) growth for 5 min, the GNSs start merging on the surface of networked double-walled CNT (DWCNT) bundles, which can obviously observe at the isolated G-DWCNTs (inset of Fig. 1(b))
These results show that the amount and density of GNSs on the DWCNT bundles strongly depend on the growth time of GNSs in the thermal CVD (TCVD) method

Summary

Introduction

Graphene[1,2] and carbon nanotubes (CNTs)[3,4] are attractive materials in low-dimensional carbon allotropes which have been received widespread attention due to their unique structure and fascinating properties, such as mechanical[5,6,7], electrical[8,9], and thermal properties[5,6,10]. The G-CNTs have the high edge density of graphene which provide higher charge density and reactivity than the basal plane Due to their unique structure and outstanding properties, G-CNTs have been widely applied in the areas of the supercapacitor[11,12,13], gas sensor[14], electronic and optoelectronic devices[14], and proton exchange membrane fuel cells[15,16]. The G-CNT hybrid was fabricated by growth of graphene directly onto the CNTs without any additional catalyst by the RF PECVD technique using acetylene. We have proposed the facile synthesis of hybrid nanostructures of graphene nanosheet (GNS) grafted double-walled CNT (DWCNT) bundles (hereafter referred to as G-DWCNTs) by two-step CVD method. The improvement in the sensor response of G-DWCNTs is attributed to the GNS-grafted on DWCNT bundles, which provides higher surface area for gas adsorption

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Conclusion