Investigating the effect of para-Toluenesulfonic acid on PANI/ZnO composite films for supercapacitor applications

In this study, we developed polyaniline/zinc oxide (PANI/ZnO) composites with para-Toluene sulfonic acid (p-TSA) as a sulfonating agent, aimed at improving their electrochemical performance for supercapacitor applications. The composites were synthesized via a wet chemical method and characterized using various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). XRD confirmed the formation of PANI and the successful integration of ZnO within the polymer matrix with the average particle size 35–45 nm, while FTIR analysis revealed the interaction between the sulfonating group (–SO₃H) of p-TSA and the composite surface. UV–Vis spectroscopy showed a blue shift in the absorption edge, indicating changes in the electronic structure induced by p-TSA. SEM and HRTEM images demonstrated a reduction in composite particle size with increasing p-TSA concentration, attributed to the prevention of particle aggregation. Furthermore, IV measurements revealed that the electrical conductivity of the composite improved with p-TSA addition, enhancing the effective surface area for electrical double-layer capacitance (EDLC). These findings suggest that p-TSA significantly improves the structural and electrochemical properties of PANI/ZnO composites, making them promising candidates for energy storage applications.