Graphene Oxide with Neodymium Oxide Composite Using Sonochemical Method as Electrode Material for Supercapacitor

Abstract

A graphene oxide (GO)–neodymium oxide (Nd₂O₃) composite was successfully synthesized using the sonochemical method. To enhance the efficiency of the composite formation during ultrasonication, cetyltrimethylammonium bromide was added as a surfactant. X-ray diffraction (XRD) analysis revealed diffraction peaks at 2θ values of 12°, 15°, 27°, 28°, 30°, 40°, 47°, 49°, 56°, 65°, and 79°, indicating the crystalline structure of the composite. Raman spectroscopy showed characteristic 2D and D + D′ bands, confirming the presence of graphene oxide. Fourier-transform infrared spectroscopy (FTIR) detected peaks at 2850 cm⁻¹ and 2925 cm⁻¹, corresponding to C–H stretching vibrations. Wide-scan X-ray photoelectron spectroscopy confirmed the presence of neodymium (Nd³⁺), and a high-resolution narrow scan of the Nd 3d region revealed distinct Nd 3d₅/₂ and Nd 3d₃/₂ peaks. Field emission scanning electron microscopy demonstrated that Nd₂O₃ particles were well dispersed and adhered to the GO surface. Energy-dispersive X-ray spectroscopy further confirmed the presence of neodymium in the composite. Electrochemical measurements showed that the specific capacitance reached 532 F/g at a current density of 1 A/g. After 10000 charge-discharge cycles, the composite retained 91% of its capacitance, indicating excellent cycling stability. Nyquist plots recorded before and after cycling revealed near-vertical lines, and the resistance values remained low and stable, showing no significant performance degradation.