Facile fabrication of bismuth molybdate nanocomposites mixed with carbon spheres to enhance supercapacitor performance

Abstract

Driven by growing global energy demand and escalating cost of fossil fuels, supercapacitors have attracted tremendous attention due to their growing market and different applications. In this study, nanocomposites consisting of bismuth molybdate (Bi₂MoO₆) nanoparticles and carbon spheres were prepared using a straightforward solvothermal method. The processed nanocomposites were characterized through standard characterization, conclusively confirming the distribution of carbon spheres and Bi₂MoO₆ in Bi₂MoO₆@CS nanocomposites. The single-phase crystalline nature of the constituent powders exhibiting an orthorhombic phase (JCPDS card no.: 76-2388) was confirmed using XRD, and the calculated average crystallite sizes of Bi₂MoO₆ and Bi₂MoO₆@CS based on the diffraction peaks were 42.80 and 28.53 nm. Electrochemical measurements demonstrated that Bi₂MoO₆@CS exhibited superior capacitive behaviour when compared to pristine Bi₂MoO₆, delivering specific capacitances of 87.3 and 47.04 F g⁻¹, respectively, at 1 A g⁻¹ in a three-electrode system. The corresponding R_s and R_ct values of Bi₂MoO₆@CS (2.6 Ω and 2.5 Ω) were low when compared to those of Bi₂MoO₆ (3.2 Ω and 2.8 Ω), indicating improved charge transfer efficiency. A two-electrode asymmetric device based on Bi₂MoO₆@CS achieved an energy density of 13.7 Wh kg⁻¹ at a power density of 499.9 W kg⁻¹, with R_s and R_ct values of 4.30 Ω and 0.30 Ω, respectively. Furthermore, the device maintained 90.5% of its initial capacitance even after 5000 charge–discharge cycles, confirming its outstanding electrochemical durability. This outcome indicates that carbon sphere integration significantly improves ion transport dynamics and electrical conductivity of Bi₂MoO₆, thereby positioning Bi₂MoO₆@CS as an efficient and long-lasting electrode material for advanced supercapacitor applications.