N, O co-doped carbon nanosheets synthesized based on polydopamine in situ grown on C3N4 template for supercapacitors

Heteroatom doped carbon materials have always been the focus of the research for supercapacitors. N, O co-doped carbon nanosheets (NOCNS) were synthesized by heating-treatment of self-polymerization of dopamine in situ grown on surface of C3N4 as a template. Morphologies and structure information were charactered by SEM, TEM, XRD, XPS, Raman and BET. The results exhibited that nanosheets morphology with thickness of about 1.4 nm and highly graphitization degree (ID/IG = 1.14). The effects of temperature and ratio of C3N4 to dopamine on electrochemical performance were investigated. The obtained NOCNS could achieve a maximum specific surface area of 190.7 m2 g−1 in an optimized condition of 800 °C and ratio of 1:2, reaching a maximum specific capacitance of 287.5 F g−1 at a current density of 0.5 A g−1. The assembled supercapacitor device could exhibit an energy density of 10.6 Wh kg−1 with a good cycle life.