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

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 2h 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.