Abstract

In this study, we report a novel room-temperature solid-state synthesis of polyaniline (PANI) using lead nitrate (Pb(NO3)2) as an oxidizing agent. Unlike conventional oxidants such as ammonium persulfate or ferric chloride, Pb(NO3)2 enables controlled oxidation, promoting the formation of highly conductive emeraldine salt structures. The synthesized PANI was characterized using FT-IR, UV-Vis, XRD, SEM-EDAX, and four-probe conductivity measurements. An optimized Pb(NO3)2:aniline ratio of 1:1.25 yielded nanogranular PANI with enhanced crystallinity and conductivity (3.9 & times; 10_ 1 S cm_ 1). The Pb-PANI-modified glassy carbon electrode (GC/Pb-PANI) exhibited excellent electrocatalytic activity toward indole-3-carboxylic acid (I3CA), showing a well-defined oxidation peak at 0.78 V (vs Ag/AgCl, pH 7), a wide linear range (1 nM-0.5 mM), and a low detection limit of 0.13 nM. The sensor demonstrated high reproducibility, stability, and satisfactory recovery in cabbage extract samples. This work introduces Pb(NO3)2 as a new oxidant for aniline polymerization and highlights its role in tailoring PANI structure and electrochemical performance, providing a promising strategy for advanced sensing applications.