Synergistic enhancement of supercapacitor performance in Ce-Bi co-doped CdO: from structural engineering to...

Along with the growing interest in sustainable energy storage solutions, research into developing advanced electrode materials with enhanced electrochemical properties has intensified. In the present work, Ce-Bi co-doped CdO nanostructures were successfully synthesized by an eco-friendly hydrothermal route. The novelty of this work is the synergistic Ce-Bi co-doping approach to simultaneously improve the structural stability and electrochemical performance of CdO electrodes. X-ray diffraction revealed the successful incorporation of Ce and Bi in the phase-pure cubic CdO with decreased crystallite size (16.3 to 13.2 nm) and increased dislocation density. The results of EDX confirmed the homogeneous incorporation of Ce and Bi, whereas TEM and HR-TEM showed uniformly distributed nanoparticles with high crystallinity and reduced lattice spacing which were in agreement with the XRD results. SEM showed the conversion of CdO from a densely packed to a porous interconnected structure that is desirable for electrolyte diffusion. The values of b obtained from cyclic voltammetry are 0.48 and 0.52, which suggests that the charge-storage mechanism is predominantly diffusion-controlled. The Ce-Bi co-doped CdO electrode had a maximum specific capacitance of 252.7 F g^-1 at a current density of 0.8 A g^-1, with a decrease in charge transfer resistance (R _ct) from 0.41 to 0.26 Ω, and an 87.3% capacitance retention after 5000 cycles, which indicated the excellent long-term electrochemical stability for supercapacitor applications. These results show that the co-doping of Ce-Bi is an effective approach to enhance the microstructure, charge transfer properties and durability of CdO-based supercapacitor electrodes.