The Effect of the Gaseous Environment on the Electrical Conductivity of Multi-Walled Carbon Nanotube Films over a Wide Temperature Range

Abstract

The surrounding gas atmosphere can have a significant influence on the electrical properties of multi-walled carbon nanotube (CNT) ensembles. In this study, we subjected CNT films to various gaseous environments or vacuum to observe how such factors alter the electrical resistance of networks at high temperatures. We showed that the removal of adsorbed water and other contaminants from the surface under reduced pressure significantly affects the electrical conductivity of the material. We also demonstrated that exposing the CNT films to the hydrogen atmosphere (as compared to a selection of gases of inert and oxidizing character) at elevated temperatures results in a notable reduction of electrical resistance. We believe that the observed sensitivity of the electrical properties of the CNT films to hydrogen or vacuum at elevated temperatures could be of practical importance.

Ultrathin and Ultrasensitive Printed Carbon Nanotube-Based Temperature Sensors Capable of Repeated Uses on Surfaces of Widely Varying Curvatures and Wettabilities

“…The temperature cycling tests that we have performed here do not quantify such long-term degradation that occurs when the sensors are exposed to ambient gases. It is worthwhile to mention in this context that a recent study has pointed out that the electrical conductivity of the CNTs is hardly affected by the presence of different gases of inert or oxidizing character across a large temperature range (25 to 300 °C) and only the presence of hydrogen as ambient gas has some effect on altering the electrical conductivity of the CNTs across this temperature range . On the other hand, GOs or r-GOs (reduced graphene oxides) are known for their interactions with various gases and, accordingly, they are often used for sensing of these gases. , Therefore, it is highly possible that the GO of the CNT-GO sensors will interact with the ambient gases, which in turn might lead to a long-term degradation of these CNT-GO sensors.…”

Highly conductive CNT aerogel synthesizedviaan inert FC-CVD technique: a step towards a greener approach

“…22,23 The structural characteristics and concentration of carbon species produced during an FC-CVD reaction are strongly related to gas chemistry and its composition. 24,25 Researchers have commonly used inert carrier gases such as nitrogen, [26][27][28] argon, [29][30][31] and helium 32,33 and reducing gases such as hydrogen 13,34,35 and ammonia 36 for the synthesis of CNT. It has been observed that the gaseous composition affects the morphology, structure, and nanotube aerial density of the final product.…”

Special Issue of Materials Focused on “Electrical, Thermal and Optical Properties of Nanocarbon Materials”

“…Due to this relation, they can be used as sensors to monitor the external environment. Firstly, it was demonstrated that the surrounding gas atmosphere can greatly impact the electrical properties of CNT networks [ 1 ]. The electrical conductivity of CNT films was changed when the material was exposed to vacuum or a selection of gases such as methane, ethylene, oxygen, ammonia, nitrogen, argon, and hydrogen.…”