Synthesis of Al-α-Fe₂O₃/rGO Nanostructures for Plasmon Enhanced Photocatalytic Herbicide (2,4-D) Degradation and Hydrogen Production via PEC Water Splitting

Abstract

This study mainly focused on the synthesis of Al-α-Fe2O3/rGO nanostructure through the sol gel method with sonication route, followed by characterization for photocatalysts degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and hydrogen production via photoelectrochemical (PEC) water splitting. The morphology, optical, structural properties, elemental composition and electrochemical properties of the prepared nanomaterial were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X ray (EDX), X-ray photoelectron (XPS), Fourier transform infrared (FTIR), Brunauer-Emmett Teller, photoluminescence (PL), ultraviolet-visible spectroscopy (Uv-Vis), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) techniques and confirmed the successful formation of crystalline hematite, lattice incorporation of Al³⁺, and intimate contact with reduced graphene oxide (rGO). The photocatalytic activity of Al-α-Fe₂O₃/rGO nanostructure was evaluated by degrading 2,4 D under visible light, achieving 93.95% removal efficiency within 60 minutes. While the PEC water splitting to produce hydrogen of Al-α-Fe₂O₃/rGO nanostructure tested in 1 M NaOH and delivered photocurrent density of 3.12 mA/cm² at 1.23 V vs RHE, which is 22.28 times higher than bare α-Fe₂O₃, and exhibited excellent stability over 35,000 seconds under continuous illumination. The enhanced attributes that Al doping improve charge separation and reduce recombination, through a plasmonic enhancer by inducing localized surface plasmon resonance (LSPR) that increases visible light absorption and promotes hot electron generation. Coupling with rGO provides an efficient charge transport pathway and results in high electrical conductivity. These findings indicate the potential of Al-α-Fe₂O₃/rGO nanostructures as efficient, stable, and low-cost plasmon-enhanced photocatalysts for environmental remediation and solar-driven PEC hydrogen production