Investigation of Gas-Sensing Property of Acid-Deposited Polyaniline Thin-Film Sensors for Detecting H2S and SO2

Abstract

Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF6, insulating medium of gas-insulated switchgear, is a feasible method of early-warning to avoid the occurrence of sudden fault. Polyaniline thin-film with protonic acid deposited possesses wide application prospects in the gas-sensing field. Polyaniline thin-film sensors with only sulfosalicylic acid deposited and with both hydrochloric acid and sulfosalicylic acid deposited were prepared by chemical oxidative polymerization method. Gas-sensing experiment was carried out to test properties of new sensors when exposed to H2S and SO2, two decomposed products of SF6 under discharge. The gas-sensing properties of these two sensors were compared with that of a hydrochloric acid deposited sensor. Results show that the hydrochloric acid and sulfosalicylic acid deposited polyaniline thin-film sensor shows the most outstanding sensitivity and selectivity to H2S and SO2 when concentration of gases range from 10 to 100 μL/L, with sensitivity changing linearly with concentration of gases. The sensor also possesses excellent long-time and thermal stability. This research lays the foundation for preparing practical gas-sensing devices to detect H2S and SO2 in gas-insulated switchgears at room temperature.

Hydrogen Sulfide Detection by Sensors Based on Conductive Polymers: A Review

“…On the contrary, the other sensors based on pristine CPs display an increasing conductivity in the presence of H 2 S. In fact, in the presence of water at room temperature, H 2 S tends to dissociate into H + and HS − (Agbor et al, 1995). H + protonates the nitrogen atoms from PANI (Agbor et al, 1995;Dong et al, 2016), polypyrrole (PPy) (Kriván et al, 2000;Garg et al, 2015), or poly(N-propylaniline) (PNPA) (Chabukswar et al, 2013) and FIGURE 1 | Mechanisms of H 2 S detection by CPs. (A) The reducing gas H 2 S induces a reduction of the major charge carrier (holes, +) resulting in an increase in CP resistance (R 0 < R).…”

“…Thus, the size and nature of the dopant can influence the sensing performance of the CPs and their stability. For example, PANI doped with hydrochloride acid (HCl) has a response five times higher than the same material doped with sulfosalicylic acid (SSA) tested toward 100 ppm of H 2 S (Dong et al, 2016). SSA anions being bigger, they lead to larger chain spacing.…”

“…They are more likely to migrate and volatilize from the CPs, leading to a drift of the resistance with time. Moreover, functional groups, such as the presence of both polar and non-polar groups on SSA, can increase the decomposition temperature (Dong et al, 2016). Those two parameters influence directly the stability of CPs.…”

Synthesis, Characterization and Enhanced Sensing Properties of a NiO/ZnO p–n Junctions Sensor for the SF6 Decomposition Byproducts SO2, SO2F2, and SOF2

“…Moreover, the responses of the prepared sensors to these three test gases at low concentration have a good linear relationship. These good linear relationships indicate that the fabricated gas sensors are more likely to be used in practice [ 39 , 40 ].…”

Electrospun natural rubber fibers-based flexible conductive membranes

“…In this sense, the materials described in this paper reached values of electrical conductivity in the semiconductor range around to 10 -6 S.m -1 for NR/PAni Fibers , and can be applied as melamine (1,3,5-triazine-2,4,6-triamine) sensor [41]; ammonia sensors [42,43]; radiation sensors [44]; H 2 S and SO 2 sensors [45] and strain sensor [46].…”