Enhanced Electrochemical Performance of TiO2 Thin Films Modified with CQD@Fe3O4 Nanocomposites

This is the first investigation of the electrochemical characteristics of a CQD@Fe3O4 composite with TiO2 thin film. Structural confirmation of CQD@Fe3O4 growth on Titanium Dioxide (TiO2) was achieved using X-ray Diffraction (XRD) and RAMAN Spectroscopy. Scanning Electron Microscopy (SEM) combined with Energy-Dispersive X-ray Spectroscopy (EDX) provided insights into the surface morphology and confirmed composite formation. Additionally, X-ray Photoelectron Spectroscopy (XPS) was employed to determine the elemental composition and oxidation states, confirming successful incorporation of CQD@Fe3O4 into the TiO2 matrix. Electrochemical analysis through Cyclic Voltammetry (CV) revealed differences in ion adsorption and charge transfer between CQD@TiO2 and CQD@Fe3O4/TiO2 electrodes, with a predominance of double-layer capacitance effects. Electrochemical Impedance Spectroscopy (EIS) further assessed charge transfer resistance, ion diffusion, and rate capability, emphasizing the role of CQD@Fe3O4/TiO2 in optimizing electrode-electrolyte interactions. Notably, CQD@ Fe3O4/TiO2 demonstrated a high specific capacitance of 170.58 F/g, significantly surpassing CQD@TiO2 (54.51 F/g), along with superior energy density (246.48 wh/kg) and power density (616.2 kw/kg). Major Findings: Electrochemical measurements demonstrated improved ion adsorption, faster charge-transfer kinetics, and reduced resistance in the CQD@Fe3O4/TiO2 system. As a result, the composite electrode exhibited significantly higher specific capacitance, energy density, and power density compared to CQD@TiO2, highlighting its superior energy-storage performance.