Ag nanoparticles decorated N/S dual-doped graphene nanohybrids for high-performance asymmetric supercapacitors

Ag nanoparticles decorated N/S dual-doped graphene nanohybrids (Ag-NSRGO) are prepared by one-step hydrothermal method. The morphology, structure and composition of the samples are characterized and compared with graphene (RGO), Ag nanoparticles decorated graphene nanohybrids (Ag-RGO) and Ag nanoparticles decorated N-doped graphene nanohybrids (Ag-NRGO). The effect of Ag content on the sample’s performance is also studied. For the sample Ag-NSRGO, Ag nanoparticles are evenly dispersed in N/S dual-doped graphene (NSRGO) to form a three-dimensional network structure and there is a pair of unique redox peaks at around −0.9 V. The performance of Ag-NSRGO is much better than that of RGO, Ag-RGO, and Ag-NRGO. When the Ag content is 35 wt%, the electrochemical performance of the sample is the best. The optimal sample exhibits a specific capacitance as high as 1010.6 F g−1 at the potential window from −1.2 to 0 V. In addition, an asymmetric supercapacitor (ASC) assembled by using Ag-NSRGO35 and NSRGO as the negative and positive electrodes achieves a maximum energy density of 40.69 W h kg−1 at a power density of 500 W kg−1 and the excellent cycling stability with 90.5% of the capacitance retained after 10000 cycles.