▎ 摘　　要

Nanoparticle self-assembly optimizes super-capacitive behaviour with sustainable life and ascertains the most optimal active material for electrodes. A nano self-assembly consisting of rare earth (RE = Ce and Gd)-doped Bi2Mo2O9 (Bi2-xRExMo2O9) and reduced graphene oxide (rGO)-modified Bi2-xRExMo2O9 (GM-Bi2-xRExMo2O9; RE = Ce and Gd) was synthesized using a gel combustion method. The phase formation of the as-synthesized nano self-assembly was confirmed using X-ray diffraction. Raman spectroscopy and XPS analysis confirmed the optical properties and chemical composition of the prepared materials. The morphology of the synthesized nano self-assemblies and their effect on the rare earth doping and rGO modification were explored using SEM and TEM. Brunauer-Emmett-Teller analysis confirmed the surface area and pore volume. Through CV, GCD, and EIS analysis, the electrochemical performance of the nano self-assembly was examined. GM-Bi2-xRExMo2O9 (RE = Ce and Gd) exhibited high specific capacitance in a three-electrode configuration along with feasible cyclic stability. The fabricated asymmetric supercapacitor device of GM-Bi1.9Ce0.1Mo2O9 and GM-Bi1.9Gd0.1Mo2O9 exhibited an extraordinary energy density of 58.96 W h kg(-1) and 56.67 W h kg(-1), respectively, with an equivalent power density of 750 W kg(-1). However, GM-Bi1.9Gd0.1Mo2O9 exhibited a higher cyclic stability of 86.55%, with the fabricated GM-Bi1.9Ce0.1Mo2O9 asymmetric device providing a superior super-capacitive performance. We improved the electrochemical performance of bismuth molybdate by rare earth doping and rGO modification, and it can potentially be a desirable electrode material.