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

• Published in: Polymer international Vol. 66; no. 5; pp. 699 - 704
• Main Authors: Chaudhary, Vishal, Singh, HK, Kaur, Amarjeet
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.05.2017; Wiley Subscription Services, Inc
• Subjects: Charge carriers; Charge transport; chemiresistor; effective surface area; Mathematical models; Monitoring; Nanofibers; polyaniline; Polyanilines; Porosity; Sulfur dioxide; variable range hopping model
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.5311

Polyaniline nanofibres (NFs) with controlled diameters were synthesized using a template‐free method, with ammonium peroxidisulfate (APS) or ferric chloride (FeCl3) as oxidants. Porosity studies reveal that NFs prepared with FeCl3 possess higher effective surface area and larger pore volume compared to NFs prepared with APS. The FeCl3‐assisted NFs show around twofold enhanced sensing response (ca 4.5%) towards 5 ppm of SO2 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 FeCl3‐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 FeCl3 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. © 2016 Society of Chemical Industry The connection between charge transport mechanism of charge carriers (variable range hopping) and sulfur dioxide (5 ppm) monitoring behaviour of high‐surface‐area polyaniline nanofibres with controlled diameters is explored in this study.