Goncalves et al. studied the electrochemical behaviour of casting-produced C3N4 electrodes as active material for high performance metal-free supercapacitors . The electrochemical studies were performed in 0.1 M LiClO4 electrolyte using a three-electrode system purged with N2. The galvanostatic charge-discharge results showed a specific capacitance value of 113.7 F g - at 0.2 A g -1 with the capacitance retention of 89.2% after 5000 charge-discharge cycles at 3.0 A g -1 . Further, the fabricated film electrode delivered the maximum specific energy of 76.5 W h Kg -1 at an operation power of 11.9 W Kg -1 , which was decreased about 10.7% after successive cycling due to the electrochemical aging process. The results of the work suggests that pristine C3N4 is a quite promising organic supercapacitor material for energy storage purposes, as it is easily prepared, cheap, metal-free, and environmentally friendly. The supercapacitive behaviour of the electrode material was tested in a conventional three electrode system using 1.0 M H2SO4 electrolyte. At 1 A g -1 , Ag/PANI/g-C3N4 electrode showed the specific capacitance of 797.8 F g -1 , with the cycling stability of 84.43 % capacitance retention after 1000 cycles, which is higher than those of PANI and PANI/g-C3N4. The higher specific capacitance in the case of Ag/PANI/g-C3N4 is attributed to the larger specific surface area, ordered structure, and porous morphology of PANI/g-C3N4 composite, and the presence of Ag nanoparticles has improved the electrical conductivity and reduced the electrical resistance. The electrochemical properties of the as-synthesized nanocomposites were analysed under a threeelectrode system using 0.5 M Na2SO4. The higher specific capacitance of 274 F g -1 at the current density of 2 A g -1 was obtained for MnO2/g-C3N4@PPy electrode while the MnO2@PPy showed a lower specific capacitance of 34 F g -1 at 2 A g -1 . Further, the cycling stability analysis of MnO2/g-C3N4@PPy electrode remained unchanged in 500 cycles and then decreased very slightly with the retention capacitance of 95% after 100 cycles. The obvious increase in the specific capacitance at MnO2/g-C3N4@PPy electrode is attributed to the presence of MnO2 which has effectively prevented the agglomeration of g-C3N4 sheets and provided more electrochemically active surface area for charge storage process. Further, g-C3N4 sheets has facilitated addition electron transfer path besides the conductive PPy coating during the charge-discharge process.