Synthesis and characterization of graphitic carbon Nitride/Cd2SnO4 nanostructures for high-performance flexible supercapacitors

The development of electrode materials based on heterojunctions shows a promising approach for enhancing electrochemical performance, offering the potential for future advancements in energy storage applications. This investigation, a graphitic carbon nitride (g-C₃N₄) matrix functioned as a supportive network, regulating the aggregation of cadmium stannate (Cd₂SnO₄) nanoparticles (NPs) thereby giving promising stability during electrochemical cycling. The optimized g-C₃N₄/Cd₂SnO₄ composite demonstrated excellent electrochemical performance, characterized by a high specific capacitance and improved cycling stability. X-ray diffraction (XRD) patterns of the composite revealed distinct crystalline phases of individual components, confirming the orthorhombic structure of the composite. The electrochemical charge storage performance of the synthesized electrode material has been evaluated in an aqueous acidic and gel-electrolyte (PVA/H₂SO₄) medium. The results indicate that among the prepared electrode materials, the g-C₃N₄/Cd₂SnO₄ sample exhibits the highest electrochemical capacitance of 601.20 Fg^-1 at 0.5 Ag^-1. Even after 5000 charge-discharge cycles, the electrode maintained its cycling stability with 94.69 % capacitance retention. The performance of the g-C₃N₄/Cd₂SnO₄ electrode was further evaluated in a gel polymer electrolyte by assembling a symmetric capacitor for real-world application using a two-electrode system. The use of a gel electrolyte allowed the device to achieve an energy density of 48.81 Wh kg⁻¹ and a power density of 250 W kg⁻¹ within a voltage window of 1.0 V at an operating current density of 0.5 A g⁻¹. Notably, the g-C₃N₄/Cd₂SnO₄ electrode demonstrated strong cycling stability in the gel electrolyte, maintaining performance for up to 5000 cycles. Furthermore, the symmetric device in the gel electrolyte exhibited excellent electrochemical stability across various bending angles, highlighting its potential for use as a flexible electrode in supercapacitors.