High performance g-C ₃ N ₄ /FeSi ₂ composites for supercapacitors: Improved capacitance and cycling stability

In this work, we prepared the g-C 3 N 4 /FeSi 2 composites by changing the FeSi 2 concentration (1%, 5%, 10% and 20%) and characterized them to determine their structural, surface morphology and electrochemical properties. X-ray diffraction analysis has confirmed the successful growth and incorporation of FeSi 2 into the g-C 3 N 4 matrix without compromising the crystallinity of the g-C 3 N 4 phase. Scanning electron microscopy revealed uniform dispersion of FeSi 2 particles within the g-C 3 N 4 sheets, with increased porosity and nanostructured morphology at higher amounts of FeSi 2 content. Electrochemical measurements, including cyclic voltammetry and galvanostatic charge–discharge tests, confirmed the improvements in electrochemical performance with increasing amount of FeSi 2 content. The g-C 3 N 4 /FeSi 2 composite with 20% FeSi 2 exhibited the highest specific capacitance of 1591.4[Formula: see text]Fg[Formula: see text] and larger energy density of 46.5 Whkg[Formula: see text] at a power density of 3500[Formula: see text]W kg[Formula: see text], highlighting its potential for high-performance supercapacitor applications. Additionally, the composite demonstrated the best long-term cycling stability, retaining nearly 100% of its initial capacitance after 10,000 cycles. These results suggest that g-C 3 N 4 /FeSi 2 (20%) composites are promising materials for advanced energy storage applications, combining high electrochemical performance with durability.