Impact of Synthesis Parameters of Multi-Walled Carbon Nanotubes on their Thermoelectric Properties.

Bogumiła Kumanek,Grzegorz Stando,Dawid Janas,Paweł S Wróbel

doi:10.3390/ma12213567

Abstract

Carbon nanotubes have been intensively researched for many years because of a wide array of promising properties that they have. In this paper, we present the impact of synthesis parameters on thermoelectric properties of nanocarbon material. We conducted a number of syntheses of multi-walled carbon nanotubes (MWCNTs) at different temperatures (800 and 900 °C) using various amounts of catalyst (2%, 5.5%, and 9.6%) to facilitate the process. We also tested the influence of injection rate of precursor and the necessity of material purification on thermoelectric properties of MWCNTs. The electrical conductivity, thermal conductivity, and Seebeck coefficient were measurement for all samples. Based on these parameters, the values of Power Factor and Figure of Merit were calculated. The results show that the most important parameter in the context of thermoelectric properties is purity of employed MWCNTs. To obtain appropriate material for this purpose optimum synthesis temperature and appropriate content of the catalyst must be selected. The study also reveals that post-synthetic purification of nanocarbon is essential to produce an attractive material for thermoelectrics.

Highlights

The global consumption of energy has been rising year by year due to the ever-increasing development of our civilization
Increase of temperature in the Chemical Vapour Depositon (CVD) process generally leads to higher amounts of defects in the material 2%-5 mL/h-900 C because side-reactions become much apparent under such conditions
The conducted research demonstrated that each synthesis parameter has an influence on thermoelectric properties of produced multi-walled carbon nanotubes (MWCNTs)

Summary

Introduction

The global consumption of energy has been rising year by year due to the ever-increasing development of our civilization. The materials with high efficiency of conversion of heat to electricity developed so far, are based on rare earth elements, which are difficult to obtain but can be very expensive and toxic [2,6,7,8,9,10]. Examples of such materials include Bi2 Te3 , Sb2 Te3 , and PbTe. The end result is that thermoelectric devices are still not present in regular households but are rather used for specialized applications. The most notable is perhaps the power system of NASA’s Voyager 2 probe launched in 1977, which in 2018 left the Solar

Methods

Results

Conclusion