Synthesis of ultra-thin polypyrrole nanosheets for chemical sensor applications

Ultra-thin polypyrrole nanosheets (UPNSs) are fabricated by organic crystal surface-induced polymerization (OCSP) of pyrrole in an aqueous suspension containing hydrated crystals of sodium decylsulfonate (C10SO3Na) below the Krafft temperature using FeCl3 as an oxidant. The hydrated C10SO3Na crystals are used as templates through electrostatic binding of the cationic polypyrrole (PPy) chains oxidized by Fe(III) ions on the anionic C10SO3Na crystal surface. The resulting UPNSs have a single layer thickness of ∼21 nm, widths between 2 and 6 μm, and lengths greater than 10 μm. The UPNSs are composed of a single continuous PPy domain. Moreover, the UPNSs exhibit higher conductivity (30.6 Scm−1) and longer conjugation lengths than the PPy nanoparticles (2.4 Scm−1) prepared using emulsion polymerization. We systematically investigate the UPNSs as gas sensors for detecting and quantifying toxic gases such as HCl and NH3. The UPNSs exhibit much higher gas sensitivity and faster response times compared with the PPy nanoparticles.