The green one-step electrodeposition of oxygen-functionalized porous g-C3N4 decorated with Fe3O4 nanoparticles onto Ni-foam as a binder-free outstanding material for supercapacitors

Abstract

In this study, the binder-free high-performance nanocomposite of Fe₃O₄/oxygen-functionalized g-C₃N₄ was fabricated through a one-pot electrophoretic-electrochemical (EP-EC) process. In this process, Fe₃O₄ nanoparticles were in situ nucleated through a two-step electrochemical-chemical (EC) mechanism on oxygen-functionalized g-C₃N₄ (O-g-C₃N₄) sheets electrophoretically embedded on a Ni-foam support. Also, pristine Fe₃O₄ nanoparticles and O-g-C₃N₄ sheets were fabricated on Ni foam (i.e. Fe₃O₄/Ni foam and O-g-C₃N₄/Ni foam) via the EC and EP processes, respectively. The prepared powders/electrodes were fully characterized through XRD, FT-IR, BET/BJH, Raman spectroscopy, TGA/DSC, FE-SEM and TEM. The morphological observations confirmed the nucleation and growth of Fe₃O₄ particles on the porous O-g-C₃N₄ sheets in the structure of the Fe₃O₄@O-g-C₃N₄/Ni foam electrode. The formation mechanisms of the pristine Fe₃O₄ particles, pristine O-g-C₃N₄ sheets and their nanocomposite on the Ni-foam support were explained based on the electrophoretic-electrochemical deposition processes. Electrochemical evaluation by galvanostatic charge–discharge (GCD) indicated that the fabricated Fe₃O₄@O-g-C₃N₄/Ni foam delivered a specific capacitance of 710 F g⁻¹ at 0.5 A g⁻¹ and capacity retention of 94.6% and 80.15% after 8000 GCD cycling at the current load of 0.5 and 3 A g⁻¹, whereas the pristine Fe₃O₄/NF showed a specific capacitance of 277 F g⁻¹ at 0.5 A g⁻¹ and capacity retentions of 82.4% and 48.9% only, under similar GCD conditions, respectively. These findings prove the superior synergism between the Fe₃O₄ nanoparticles and oxygen-functionalized g-C₃N₄ sheets in the composite structure.