Impact of Pt/C on improving alternating current response in polyaniline-based ternary composites

Platinum on carbon (Pt/C) catalysts with different wt% (2, 4, 6, 8, and 10) were incorporated into silver-decorated polyaniline (PANI) via a green chemistry approach during in situ polymerization to obtain ternary composites. FTIR and EDX studies confirmed the formation of the ternary composites, while XRD spectra exhibited the crystalline nature of the composites. SEM images exhibited the agglomerated flake-like structures with a porous morphology. The measurement of AC conductivity for Ag-PANI-Pt/C-2% across the frequency range of 50 Hz to 1 MHz revealed a significantly elevated conductivity of 1.3 × 10^–2 S/cm, representing a threefold enhancement compared to pure PANI and a twofold increase relative to the composite of Ag-PANI. The composite exhibits a high dielectric constant, approximately 10⁴, along with low loss characteristics, indicating its potential suitability for mid-frequency device applications. Humidity studies of the composite PANI-Pt/C-2% in the range (11%RH – 97%RH) evidenced a sensitivity of 5.8 × 10⁵ Ω cm/%RH, a LOD of 2.32%RH, with an excellent linearity of 0.9995. The Activation energy of 0.1 eV obtained for the PANI-Pt/C-2% sample is favourable for a physisorption based mechanism in humidity sensing.