Engineering few-layer MoS2 and rGO heterostructure composites for high-performance supercapacitors

Molybdenum disulfide (MoS2) after the few-layer (FL) processing draws attention to its attractive characteristics, such as broadening interlayer spacing, increasing active sites, and promoting purity of the metallic phase. Notwithstanding, the poor stability and easy aggregation of FL-MoS2 limit its potential for development in the field of electrochemistry. Herein, a nanocomposite between FL-MoS2 and reduced graphene oxide (rGO) is successfully constructed via the one-pot hydrothermal method. Furthermore, the FL-MoS2@rGO composite with a stable structure is obtained by regulating the amount of rGO. The excellent supercapacitor capacitances of FL-MoS2 after building heterostructure composites with rGO are displayed, owing to the synergistic effects occurring in heterostructure. The optimal sample of FL-MoS2@rGO-2 possesses a specific capacitance of 346.1 F g−1 at 1 A g−1 and a rate ability of 57.2%. Moreover, the capacitance of FL-MoS2@rGO-2 remains 99.1% after 10,000 cyclic charges and discharges. More importantly, the theoretical calculations confirm the source of extra specific capacitance and raise conductivity in FL-MoS2@rGO. Also, a FL-MoS2@rGO-2//AC flexible asymmetric supercapacitor device is successfully fabricated, which presents the superior energy density and power density of 84.31 µWh cm−2 at 700 µW cm−2, and 51.42 µWh cm−2 at 3500 µW cm−2. This work verifies the potential of the heterostructure composite constructed by FL-MoS2 in energy storage of electrochemical application.