Tailoring Graphitic Carbon Nitride with Sodium Tin Oxide for High-Performance Supercapacitors

In this work, we successfully fabricated a nanocomposite using a simple wet-chemical and thermal processing by integrating Na₂SnO₃ with g-C₃N₄. To the best of our knowledge, this is the first report on the application of Na₂SnO₃@g-C₃N₄ hybrids as supercapacitor electrodes, where the integration of redox-active Na₂SnO₃ with the nitrogen-rich g-C₃N₄ matrix enhances ion diffusion, pseudocapacitive contribution, and cycling durability. Structural and chemical characterizations (XRD, FESEM, HRTEM, EDX, FTIR, and XPS) confirmed the uniform attachment of ~3.5 nm Na₂SnO₃ nanoparticles on porous g-C₃N₄ nanosheets and the presence of Sn4+ with strong interfacial bonding. Electrochemical measurements revealed that the optimized Na₂SnO₃@g-C₃N₄ (2:1) electrode delivered a high specific capacitance of 491 F g⁻¹ at 0.4 A g⁻¹. The kinetic analyses indicated a synergistic double-layer and pseudocapacitive charge-storage mechanism. Notably, the electrode retained ~90% of its capacitance after 2000 cycles, with post-cycling FESEM and FTIR confirming excellent structural and chemical stability.