Positional effects of chlorine-substituted polyaniline reinforced with feco₂s₄ on HER and supercapacitor performance

We synthesized and evaluated poly(aniline-co-chloroaniline) (ClPani) catalysts, including 2-ClPani, 3-ClPani, 4-ClPani, and 2,6-diClPani, for hydrogen evolution reaction (HER) and supercapacitor applications. The structural and morphological characteristics of the catalysts were examined using Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, energy-dispersive X-ray (EDX), and scanning electron microscopy (SEM) techniques. Among the ClPani catalysts, 4-ClPani exhibited the highest HER activity, as evidenced by its low overpotential and small Tafel slope values. The addition of FeCo₂S₄ chalcogenide to 4-ClPani significantly enhanced its HER performance with overpotential (-558 mV at 100 mA cm⁻²) and Tafel slope (53.8 mV dec⁻¹), surpassing Pt and showcasing excellent stability. In supercapacitor applications, 4-ClPani again outperformed the other catalysts, displaying superior discharge time, specific capacitance (769.2 (F g^-1)), and energy density (26.7 (Wh kg^-1)). These results highlight the potential of ClPani-based materials for efficient electrocatalysis and high-performance energy storage, with strategic modifications leading to significant performance enhancements.