Study On The Preparation Of SnO₂/MWCNTs Nanocomposites And Application Of The Sulfur-containing Gas Detection

The emission of gas pollutants into the environment, either from man-made or natural processes, is a topic that generates considerable scientific interest and public concern. Especially, the detection of the sulfur-containing gases such as SO₂ and H₂S has drawn much social solicitude because of the increasingly serious acid rain problems. Therefore, there is a great deal of importance in developing chemical sensors which allow rapid monitoring and detection of sulfur-containing gaseous contaminants.The research on the gas-sensing nanocomposites has attracted much interest in recent years. As a typical n-type semiconductor with special electrical properties and excellent stability, tin oxide (SnO₂) has been widely used because of the disvantages such as robust nature, simple interface electronics, and strong response. Carbon nanotubes (CNTs) are considered as a competitive material for gas sensing because of the high specific surface area for gas adsorption, nanoscale structure with numerous sites for the chemical reaction, and their special metal or semiconductor properties with electron transport.In this paper, the SnO₂/MWCNTs nanocomposites were prepared by hydrothermal method. The experimental results showed that SnO₂ nanoparticles were attached on the surface of the MWCNTs, mainly and firstly centered on the knots and the defects of the CNTs. The agglomeration of SnO₂ particles belong to tetragonal crystallographic system and were evaluated to have a diameter of around 10 nm.The gas-sensing properties of as-prepared SnO₂/MWCNTs nanocomposites to H₂S and SO₂ are discussed. The chemical sensors based on SnO₂/MWCNTs nanocomposites exhibited good sensitivity in response to H₂S and SO₂ at 70℃. The recovery properties can be improved significantly by UV light irradiation. The response decreased by 22% for H₂S and 16% for SO₂ respectively under UV illumination for sensor recovery after 4 replicates. A possible sensing mechanism was proposed. The performance of the hybrid nanostructure sensor could be contributed to improved structural and electronic properties of the SnO₂/MWCNTs.The detection of dissociated SF₆ species, generated by partial discharge (PD), is of great importance because the dissociated compositions can alter inherent potential of SF₆ and pose safety risks to power systems. Here we further developed the usage of SnO₂/MWCNTs nanocomposites to the detection of SF₆ dissociated species. The results show that SnO₂/MWCNTs sensors exhibited good sensitivity in response to decomposition components at room temperature. The sensitivity of SnO₂/MWCNTs sensors would grow larger with the duration of partial discharge. This is because the longer-lasting partial discharge would result in the higher concentration of the SF₆ degradation products, and therefore the more gas molecules interacts with the SnO₂/MWCNTs nanocomposites in the gas-sensing process. Moreover, the types of gas involved in the gas-sensing process may be SO₂F₂, SOF₂, SO₂.