Co-doped amorphous NiMoS 4 modified with rGO for high-rate performance and long-cycling stability of hybrid supercapacitors.

The electrochemical performance of hybrid capacitors is seriously affected by the slow charging and discharging of the bulk phase. Here, Co-doped amorphous NiMoS ₄ modified with reduced graphene oxide (rGO) was prepared by a simple one-step hydrothermal method, and the obtained Co-doped NiMoS ₄ /rGO nanocomposite (Ni _{1- x} Co _x MoS ₄ /rGO) exhibits a high specific surface area, realizing the redox reaction from the bulk to the surface. Owing to the doping of Co with abundant redox active sites and the support of rGO sheets with high conductivity and a stable structure, the Ni _{1- x} Co _x MoS ₄ /rGO anode assembled with an oxidized needle coke (NCO) cathode shows an excellent energy density of 28.9 W h kg ^-1 at a power density of 968.3 W kg ^-1 . In addition, the hybrid supercapacitor displays a superior cycling performance with a capacity retention of 92.4% after 10 000 cycles. The construction of the Co-doped NiMoS ₄ /rGO nanocomposite provides an effective strategy to boost the activity and stability of amorphous NiMoS ₄ for high-performance hybrid supercapacitors.