Promising carbon nanosheets decorated by self-assembled MoO2 nanoparticles: Controllable synthesis, boosting performance and application in symmetric coin cell supercapacitors

A composite containing self-assembled MoO2 nanoparticles and functional carbon nanosheets was obtained via a facile and controllable strategy. Two-dimensional functional carbon nanosheets as matrices have close contact with MoO2 nanoparticles, which assists in the improvement of electronic conductivity, provides efficient pathways and accelerates electron transfer. The carbon nanosheets have functional groups on the surface, which could serve as the nucleation sites for MoO2. The MC-0.12 composite shows optimal specific capacitance (190.9 F g(-1) at 1 A g(-1)) and excellent cycle stability between monomers and composites with different constituents. The assembled symmetrical coin cell supercapacitor using MC-0.12 possesses the maximum energy density of 10.3 Wh kg(-1) at a power density of 378 W kg(-1) and still maintains the energy density of 7.9 Wh kg(-1) at 1682 W kg(-1) with a larger potential window. The capacitance retention (92%) of the assembled device is maintained after 2000 cycles, showing outstanding cycle life. Therefore, the integration of self-assembled MoO2 nanoparticles with 2D functional carbon nanosheets provides the composite superior electrochemical performance for supercapacitor applications.