Development and performance evaluation of g-C3N4-based ternary metal oxide nanocomposites for high-efficiency supercapacitor applications

[Display omitted] •Development of C3N4/Fe2O3/NiO/Dy2O3 and g-C3N4/ZnO/Fe2O3/SrO2 nanocomposite materials for energy production and storage.•The g-C3N4/ZnO/Fe2O3/SrO2 nanocomposite showed the highest specific capacitance.•The findings suggest g-C3N4-based nanocomposites have potential for supercapacitor applications. The focus in recent years has been on developing innovative, green technologies for energy production and storage. Nanocomposite materials are attractive due to their exceptional performance, diverse compositions, and unique architectures. Multi-metal nanohybrids, particularly combining transition metal oxides with high surface-area carbon nanostructures, offer significant benefits over single-component materials for energy harvesting and storage. This study focuses on the preparation of g-C3N4/NiO/Fe2O3/Dy2O3 and g-C3N4/ZnO/Fe2O3/SrO2 nanocomposites. Metal oxide nanoparticles were synthesized using co-precipitation and sol–gel methods, while g-C3N4 was prepared via thermal exfoliation. Ternary metal-based nanocomposites were produced using a sono-chemical technique. The ternary metals based g-C3N4 nanocomposites shows enhanced electronic conductivity and charge transport, improved ion diffusion and reduced resistance through synergistic effects. The conductive and structural properties of g-C3N4 provides increased specific capacitance, stability, and cycling performance by buffering volume changes. The tailored design allows optimization for charge storing performance. The g-C3N4/ZnO/Fe2O3/SrO2 nanocomposite demonstrated the highest specific capacitance, with an areal capacitance of 84,570 mFcm−2, a potential window of 0.8 V, at a scan rate of 2 mVs−1 and a mass of 0.03 mg. In contrast, the g-C3N4/NiO/Fe2O3/Dy2O3 nanocomposite exhibited a lower specific capacitance and areal capacitance of 30,070 mFcm−2 at scan rate of 2 mVs−1. These findings highlight the potential of g-C3N4-based nanocomposites for supercapacitor applications.