Electrochemical Performance of Chemically Integrated N-Doped Carbon Dots/Bi2MoO6 Nanocomposites for Symmetric Supercapacitors

Abstract

Mixed transition-metal oxides (MTMOs) are attracting tremendous attention as a battery-type electrode due to their high electrical conductivity and structural stability. However, utilizing these electrodes in practical applications is hindered by capacity degradation, especially during the long-term cycle. These limitations could be overcome by constructing electrodes by introducing the carbonaceous material into the MTMO matrix. Accordingly, in this work, a facile hydrothermal method is employed to develop nitrogen-doped carbon dots (NCDs)-integrated bismuth molybdenum oxide (Bi2MoO6; BMO) (NCD/BMO) composites, where the concentration of NCDs is varied, such as 2, 5, 10, and 15 wt %. The structural and chemical state analyses of the samples confirm the formation of the orthorhombic BMO system and the chemically integrated NCD/BMO composites. The morphology analysis revealed a brick-like structure for bare-BMO with an average size of ∼100 nm and a rod-like morphology for the NCD/BMO composites, which is attributed to the interaction of NCDs with growing BMO particles leading to the rod-like formation of the resultant composites. The electrochemical performance of the developed materials is studied in a three-electrode and symmetric assembly system. Among the composites, the 10 wt % NCD/BMO (BMO–C10) composite exhibited an enhanced specific capacity of 561 C g–1 (155.8 mA h g–1) at a current density of 1 A g–1 in 6 M KOH electrolyte. Besides, the assembled symmetric device achieved an energy density and a power density of 44.2 W h kg–1 and 720 W kg–1, respectively, at a current density of 1 A g–1. In addition, the assembled symmetric device maintained excellent cyclic stability of ∼87.3% up to 10,000 cycles at 20 A g–1 current density. The obtained results demonstrate that the NCD/BMO composite could be an efficient battery-type electrode material for promising supercapacitor applications.