Effect of charge carrier transport on sulfur dioxide monitoring performance of highly porous polyaniline nanofibres

Abstract

Polyaniline nanofibres (NFs) with controlled diameters were synthesized using a template-free method, with ammonium peroxidisulfate (APS) or ferric chloride (FeCl 3 ) as oxidants. Porosity studies reveal that NFs prepared with FeCl 3 possess higher effective surface area and larger pore volume compared to NFs prepared with APS. The FeCl 3 -assisted NFs show around twofold enhanced sensing response (ca 4.5%) towards 5 ppm of SO 2 at room temperature compared to APS-assisted NFs (ca 2%). The enhancement can be attributed to the lower diameter, higher effective surface area and larger porosity of FeCl 3 -assisted NFs. To further explain this enhanced sensing response, the conduction mechanism was studied. NFs possessing a smaller diameter (ca 10 nm) are found to follow the one-dimensional variable range hopping (VRH) model, whereas NFs with larger diameter (ca 100 nm) follow the conventional three-dimensional VRH model. This can be due to the restriction of charge carrier transport into only one direction due to quantum size effects. Furthermore, the calculated Mott parameters suggest that the NFs prepared using FeCl 3 provide a better pathway for charge transport of charge carriers as compared to NFs prepared using APS in terms of shorter hopping distance, lower activation energy and lower hopping energy, and weaker localization of charge carriers.

Emerging MXene–Polymer Hybrid Nanocomposites for High-Performance Ammonia Sensing and Monitoring

“…For instance, controlling conductivity and morphology of sensing material is a crucial parameter in state-of-the-art sensors. It has been revealed that materials with superior conductivity are utilized to detect reducing analytes such as NH 3 [ 11 , 42 , 69 ] and that lower conductivities are suitable for monitoring oxidizing analytes such as sulfur dioxide [ 70 , 71 , 72 ]. Hence, the desired properties of sensing materials are optimized during the synthesis process by varying operational parameters.…”

Novel methyl‐orange assisted core‐shell polyaniline‐silver nanosheets for highly sensitive ammonia chemiresistors

“…Further, T 90 and T R90 calculations were done for both the fabricated chemiresistors to evaluate the response and recovery time for 5 ppm of ammonia at 27°C and 50% RH (Figure 12). The 90% of the elevation curve, that is, the response time 12,13 was found to be around 271 s for both the sensors.…”

“…The sensing response of PA‐2 sensor is found to be highest for ammonia amongst all reducing and oxidizing analytes, which clearly indicated its optimal selectivity. The selectivity of PA‐2 can be ascribed to the characteristic of analyte adsorbed and sensor surface 12,13 . Further, the sensing mechanism for reducing and oxidizing analytes is opposite, which can easily be picked out by electronic circuitry 12,13 …”

“…The selectivity of PA‐2 can be ascribed to the characteristic of analyte adsorbed and sensor surface 12,13 . Further, the sensing mechanism for reducing and oxidizing analytes is opposite, which can easily be picked out by electronic circuitry 12,13 …”

“…Amongst all CPs, PAN is extensively researched due to its unique redox behavior, ease of processing, low cost of monomer and varying conductivity from insulating regime to conducting regime. Hence, it is used in a wide range of research fields including sensors, 12–14 batteries, 15 electrochromic materials, 11 and supercapacitors 16 . Recently, PAN is composed with various inorganic nanomaterials including metal oxides such as tungsten oxide, 17 carbon nanomaterials such as reduced graphene oxide, 16,18,19 and MNPs such as silver (Ag), gold, copper, and platinum 20–22 .…”