Growth of MWCNTs on Plasma Ion-Bombarded Thin Gold Films and Their Enhancements of Ammonia-Sensing Properties Using Inkjet Printing

Udomdej Pakdee,Ananya Thaibunnak

doi:10.1155/2019/3424915

Abstract

Multiwalled carbon nanotubes (MWCNTs) have been synthesized on thin gold (Au) films using thermal chemical vapor deposition (CVD). The films were evolved to catalytic Au nanoparticles (Au NPs) by plasma argon (Ar) ion bombardment with a direct current (DC) power of 216 W. The characteristics of the MWCNTs grown on Au catalysts are strongly dependent on the growth temperature in thermal CVD process. The MWCNTs were then purified by oxidation (550°C) and acid treatments (3 : 1 H2SO4/HNO3). After purifying the MWCNTs, they were dispersed in deionized water (DI water) under continuous sonication. The MWCNT solution was then ultrasonically dissolved in a conducting polymer mixture of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to prepare for an electronic ink. The ink was deposited onto the flexible and transparent plastic substrates such as polyethylene terephthalate (PET) with fabricated silver interdigitated electrode using two methods such as drop-casting and inkjet printing to compare in the detection of ammonia (NH3) and other volatile organic compounds (VOCs) at room temperature. Based on the results, the gas response, sensitivity, and selectivity properties of MWCNT-PEDOT:PSS gas sensor for NH3 detection are significantly enhanced by using inkjet printing technique. The sensing mechanism of fabricated gas sensor exposed to NH3 has been also proposed based on the swelling behaviour of polymer due to the diffusion of NH3 molecules into the polymer matrix. For the MWCNTs, they were mentioned as the conductive pathways for the enhancement of gas-sensing signals.

Highlights

Carbon nanotubes (CNTs) and their composites have attracted increasing attention in various applications for several years [1,2,3,4,5]
There have been extensive reports to demonstrate the growth of CNTs by using gold nanoparticles (Au NPs) as catalysts [11,12,13,14]. e catalyst behaviour of Au nanoparticles (Au NPs) can be presented when its particle size is reduced into nanoscale caused by size effects [14]
A 10 nm Au lm with an Al2O3 bu er layer was chosen to understand the morphology of the catalyst during the Chemical vapor deposition (CVD) process. e sample was replicated in all CVD conditions without the carbon source

Summary

Introduction

Carbon nanotubes (CNTs) and their composites have attracted increasing attention in various applications for several years [1,2,3,4,5]. Chemical vapor deposition (CVD) is one of the most popular techniques for growing the CNTs. Chemical vapor deposition (CVD) is one of the most popular techniques for growing the CNTs In this technique, metal catalyst particles or islands were presented as an important factor for growing the MWCNTs [10]. There have been extensive reports to demonstrate the growth of CNTs by using gold nanoparticles (Au NPs) as catalysts [11,12,13,14]. E evolution of thin Au films to nanoparticles using thermal annealing and plasma ion bombardment was successfully reported for growing the CNTs [13]. For gas-sensing applications, the CNTs can be promoted as a good material due to its excellent properties such as high specific surface area, good electric conductivity, and high carrier mobility [15, 16]

Methods

Results

Conclusion