Tuning the electrochemical performance of a hierarchical MoO3/CdO binary heterostructure for supercapacitor applications

Abstract

Cadmium oxide (CdO)-incorporating molybdenum trioxide (MoO₃) nanocomposites were synthesized using a facile hydrothermal method by varying the CdO content (1%, 3%, and 5%) to comprehend the influence of CdO concentration on the electrochemical performance of MoO₃. The structural and morphological properties of the synthesized nanomaterials were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). XRD showed that MoO₃ has an orthorhombic structure, and FE-SEM showed that it has a nanobelt shape (0.8–3.2 μm long and 100–228 nm wide) with CdO nanoparticles grown on its surface. Electrochemical properties were analyzed through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The 3%CdO-incorporating MoO₃ electrode exhibited a higher specific capacitance of 671 F g⁻¹ at a current density of 0.50 A g⁻¹, while the pristine MoO₃ shows 386 F g⁻¹. Kinetic analysis of CV data indicates that redox processes in the nanocomposite electrodes involve both capacitive and diffusion-controlled mechanisms. The MoO₃/CdO (3%) electrode showed low charge transfer resistance (2.35 Ω) and series resistance (6.20 Ω), enabling faster faradaic redox reactions and improved electrochemical performance. Moreover, the MoO₃/CdO (3%) electrode demonstrated excellent cycling stability, retaining more than 92% of its initial specific capacitance after 5000 cycles. The incorporation of CdO enhances the diffusion pathways within the nanocomposites, potentially boosting their conductivity and specific capacitance. The symmetric supercapacitor MoO₃/CdO (3%)//MoO₃/CdO (3%) exhibited a notable operating voltage of 1.6 V, achieving an energy density of 124 W h kg⁻¹ at a power density of 1067 W kg⁻¹. It also exhibited a capacitance retention of 88.9% after 5000 cycles at a current density of 15 A g⁻¹, highlighting its potential for energy storage applications.