Tailoring graphitic carbon nitride for ultracapacitor electrode application through nanocompositing with SnO2 and WO3

Supercapacitors are a promising and necessary pillar that can aid the full-fledged adoption of intermittent renewable energy resources and emerging portable technologies. The performance of supercapacitors largely depends on the physicochemical properties of the electrode materials, which are centred on design and composition. The g-C 3 N 4, as a 2D graphitic material, has long been recognised as a suitable electrode material for supercapacitors due to readily available sources. However, limited electro-active surfaces and low conductivities have posed significant challenges. Modifying physicochemical properties through compositing has emerged as a suitable approach to enhance their applicability in energy storage by generating hybrid electrode types. In this context, the current work investigated SnO 2 nanoparticles and WO 3 nanorods as enhancers of g-C 3 N 4 nanosheets in binary (WO 3 -g-C 3 N 4 and SnO 2 -g-C 3 N 4 ) and ternary (SnO 2 -WO 3 -g-C 3 N 4 ) nanocomposites for applications in supercapacitor electrodes. Properties were synergistically tailored; for instance, charge transfer resistance of SnO 2 -WO 3 -g-C 3 N 4 , g-C 3 N 4 , SnO 2 -g-C 3 N 4 , and WO 3 -g-C 3 N 4 were 1.55, 1.26, 0.8 and 0.48 Ω, respectively. Consequently, incorporation of SnO 2 and WO 3 amplified energy storage by 119% and 172% in binary nanocomposites, while the ternary nanocomposites showed an improvement of 192%. The SnO 2 -g-C 3 N 4 , WO 3 -g-C 3 N 4 and SnO 2 -WO 3 -g-C 3 N 4 materials attained cycle stability of 70, 96, and 50%, respectively, after 2000 cycles. Other key synergism attributes from the work include morphological transformations that enhanced structural rigidity, intimate connectivity through chemical linkages, improved electro-active surfaces, and additional pseudo-capacitive contributions in the nanocomposites. The studied nanocomposites highlight that g-C 3 N 4 can be favourably tuned in this manner and pave the way for significant potential in sustainable electrodes for abundant, clean, and renewable electrochemical energy. • Pristine g-C 3 N 4 has low electro-active surfaces and poor electronic conductivity. • Electrode characteristics improved by binary and ternary nanocomposites synthesis. • Aim was hydrothermal synthesis of g-C 3 N 4 nanocomposites with SnO 2 and WO 3 . • Morphology, electro-active surfaces, and capacitive traits tuned in nanocomposites. • SnO 2 -WO 3 -g-C 3 N 4 nanocomposite displayed the highest improvement in capacitance.