The Fundamental Research Of Hydrogen Sulfide Gas Sensor

This paper mainly focused on the basis exploration for the study of hydrogen sulfide gas sensors. As one of widely existed the air pollutants, hydrogen sulfide(H2S) is corrosive, highly toxic and flammable. Therefore, the detection of hydrogen sulfide is of great importance to the industry and our daily life.Based on the results of hydrogen sulfide gas sensor in theoretical and experimental studies until now, different sensitive materials and different types of devices were utilized to fabricate the hydrogen sulfide gas sensors in this paper, and their sensing properties were tested at room temperature. The main research work was summarized as follows:1. The quartz crystal microbalance(QCM) sensor was studied to detect H2 S. Polyvinylpyrrolidone(PVP) was selected as the sensitive material and deposited on the QCM devices by air spray. Besides, the sensing properties of different amounts of PVP(0.1ml, 0.2ml, 0.3ml)were compared in the experiments. The results showed that the prepared sensors performed excellent linearity and selectivity, in spite of the long response time, recovery time and poor stability. In addition, 0.2ml PVP was an optimal quantity to detect H2 S. The scanning electron microscope(SEM) showed that the surface of the film was not flat, which increased the surface area to adsorbing gas. Then, PVP/MWCNTs(polyvinylpyrrolidone/multiple-walled carbon nanotubes) film was prepared, but the layered film failed to improve the sensing properties. Finally, DPPD was also utilized on the QCM device, but the response was completely no reply.2. The resistance-type hydrogen sulfide gas sensors based on the structure of plane interdigitated electrodes were studied. The sensing properties of MWCNTs to H2 S had been tested and analyzed. The results exhibited that the sensors performed good response and linearity, while poor repeatability, selectivity and stability, which need for further improvement. The MWCNTs film was uniform, but accumulated within a certain range, which was not conducive to desorption.3. According to the previous results, PVP/MWCNTs and PVA/MWCNTs(polyvinyl alcohol/multiple-walled carbon nanotubes) composite films were used to fabricate resistance-type H2 S gas sensor. PVP/MWCNTs film showed excellent sensing characteristics to H2 S with good response-recovering properties, repeatability, selectivity and stability, although the response was smaller than that of MWCNTs. Compared with MWCNTs, the properties were greatly improved, the only flaw was the emergence of saturation phenomenon at high concentrations. Meanwhile, the concentration of PVP aqueous solution had little influence on the sensing response. In the film, MWCNTs and PVP were embedded mutually and mixed very uniform. The response of PVA/MWCNTs was small, and its repeatability and selectivity were poor. Especially, the response exited serious baseline drift and greatly changed after 11 days, so it’s not suitable to be utilized as sensitive material of H2 S. Finally, PECH(polyepichlorohydrin) and EC(ethyl cellulose) had been attempted, but their layered films with MWCNTs had no reply to H2 S.