PEDOT/g-C3N4 binary electrode material for supercapacitors

•PEDOT and g-C3N4 were used to modify electrodes by a layer-by-layer assembly method for supercapacitors.•The specific capacitance of PEDOT/g-C3N4 electrode is almost double that of the PEDOT electrode.•Composite electrode represented 17.5 W h kg−1 of E at a P of 5000 W kg−1 in 1 M Na2SO4.•PEDOT/g-C3N4 electrode exhibited over 96.5% capacitance stability after 1000 cycles in 1 M Na2SO4.

A novel electrode material for supercapacitor composed of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT) and graphitic-phase C3N4 (g-C3N4) was prepared by a layer-by-layer assembly method. The resulting composite of PEDOT/g-C3N4 represented excellent electrochemical stability in neutral electrolyte and enhanced electrochemical performance of capacitance and average energy density in comparison with single PEDOT. The specific capacitance was 137 F g−1 in H2SO4 and 200 F g−1 in Na2SO4 at a current density of 2 A g−1, respectively. More significantly, the average energy density was 9.65 W h kg−1 at an average power density of 4001.86 W kg−1 in H2SO4. While in Na2SO4, the average energy density reached 17.5 W h kg−1 at an average power density of 5000 W kg−1. More than 89% and 96.5% of capacitance were retained in H2SO4 and Na2SO4 respectively, suggesting that PEDOT/g-C3N4 possessed an excellent cycling stability in view of capacity performance as electrode materials. The property improvement was attributed to the synergistic effects of the two components in the composite.