Conductive Polymer Composites for Hydrogen Sulphide Sensors Working at Sub-PPM Level and Room Temperature

Abstract

Hybrid composites based on tin chloride and the conductive polymers, polyaniline (PAni) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), were integrated into high-performance hydrogen sulphide (H2S) gas sensors working at room temperature. The morphology and chemical properties were studied by scanning and transmission electron microscopy (SEM, TEM), energy dispersive spectroscopy (EDS) and Fourier-transform infrared (FTIR). The composites demonstrated a slightly porous nanostructure and strong interactions between the polymers and the metal salt, which slightly dopes PAni. The hybrid sensors exhibited a very low detection limit (<85 ppb), fast response, repeatability, reproducibility and stability over one month. Moreover, this work presents how calibration based on the derivative of the signal can give hybrid sensors the ability to quantify the concentration of targeted gas, even during continuous variation of the analyte concentration. Finally, the effect of interfering species, such as water and ammonia, is discussed.

Optimizing Polyaniline-Based Gas Sensors for Hydrogen Sulfide Detection: The Crucial Role of Solvent Choice

“…To facilitate a comparison between the two composite dispersions, we prepared them as follows: we mixed 50 mg of PAni and 50 mg of SnCl 2 in 10 mL of solvent (DMF or DMSO). The processing steps, including stirring speed, temperature, sonication parameters, and time, were carried out following the protocol described in [4]. Next, the dispersions of PAni:SnCl 2 in DMF and DMSO were deposited on interdigitated electrodes using a drop-casting method, and the resulting films were dried in an oven at 90 • C under vacuum for 5 days.…”

“…PAni has controllable conductivity through redox and acid/base reactions, and has been used in various gas-sensing applications, especially in the detection of ammonia. Among the methods used to make PAni selective towards H 2 S, adding metal chloride has shown a higher potential [4]. This work focuses on the fabrication of PAni and tin chloride composite films from dispersions in DMF and DMSO, with the aim of evaluating the impact of the solvent on their response to H 2 S exposure at sub-ppm levels in order to replace the actual hazardous DMF with a safer substitute.…”

State of the Art of Chemosensors in a Biomedical Context

“…Still, commonly used polymer materials are not strictly specific against a single analyte, but rather show variable sensitivity against various volatile compounds. Various conductive polymers are known for their affinity to a variety of these compounds, e.g., polythiopenes (e.g., P3HT) for ammonia and amines [136], polyanilines for hydrogen sulfide [137] (see Figure 7), xylenes [138], or NO 2 [139], polypyrrole for ammonia and indoles [140], poly(vinyl alcohol) for hazardous gases [141], poly(methyl methacrylate) for ethyl acetate and toluene [142]. Furthermore, a wide range of composites for conductive polymers (e.g., graphene composites) and nanowire application of CPs have been demonstrated as suitable approaches for gas sensing [143,144].…”

Optimization of Printed Polyaniline Composites for Gas Sensing Applications

“…Hence, several different conductive polymers with different but overlapping specificities need to be combined in order to achieve more powerful eNose systems. PANI composites show sensitivity towards a variety of compounds e.g., hydrogen sulfide [ 19 ], xylenes [ 20 ], and NO 2 [ 21 ]. The aim of our study is the realization of cost-efficient sensor units, suitable for IoT applications, with low energy consumption, scalable fabrication methods, and efficient preparation of the functional materials needed.…”