Preparation and supercapacitor performance of melamine-modified 12-molybdophosphate and its N-doped carbon-coated copper and molybdenum carbide derivatives

The preparation of melamine-modified polyoxometalate and its derivatives and the study of supercapacitor performance are challenging. Herein, CuH{PMo12O40}@Cu(Melamine)(3) (abbreviated as {PMo12O40}@Cu-Melamine) was synthesized by solution method, and a novel nitrogen-doped carbon-coated copper and molybdenum carbide (Cu-Mo2C@NC) was prepared by calcination at 800 degrees C under nitrogen protection. The structure and morphology of the compounds were characterized by IR, XRD, XPS, SEM, TEM, and other methods. The supercapacitor properties of {PMo12O40}@Cu-Melamine and Cu-Mo2C@NC were compared. The results show that the specific capacitance of Cu-Mo2C@NC (891.92 F g(-1)) is much higher than that of {PMo12O40}@Cu-Melamine (628.52 F g(-1)) when the current density is 1.44 A g(-1) and glass carbon is used as the collector. The kinetic analysis shows that the charge storage mechanism is mainly controlled by surface charge. The CuMo2C@NC after 10,000 cycles, the capacitance retention rate is 89.95% higher than {PMo12O40}@Cu-Melamine. Moreover, the energy density of Cu-Mo2C@NC-NF (nickel foam) assembled symmetric supercapacitor is 5.69 Wh kg(-1) at 577.01 W kg(-1), and the cycle stability is good (94.47%), which is better than {PMo12O40}@Cu-Melamine. Thus, Cu-Mo2C@NC is expected to be a promising candidate for electrochemical capacitors. This work opens up a new way to fabricate supercapacitor materials with excellent performance.