Self-assembled hematite (α-Fe₂O₃) nanotube arrays for photoelectrocatalytic degradation of azo dye under simulated solar light irradiation

Self-assembly aligned hematite (α-Fe₂O₃) nanotube arrays (α-Fe₂O₃ NTs) were successfully prepared on the Fe foils by a simple two-step electrochemical anodization method in NH₄F organic electrolyte. The α-Fe₂O₃ NTs electrodes were characterized by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, grazing incidence X-ray diffraction, UV-vis absorbance spectra, and X-ray photoelectron spectroscopy. The resulting α-Fe₂O₃ NTs showed a pore diameter of 40 nm, thickness of 2 μm, and a minimum wall thickness of ∼10 nm. The systematic photoelectrochemical responses on the α-Fe₂O₃ NTs electrodes were presented. The maximum photoconversion efficiencies of 0.51% and 0.60% were collected at 0.3 V under illumination of visible light and simulated solar light (AM 1.5G), respectively. The photoelectrocatalytic (PEC) and photocatalytic (PC) activities of the α-Fe₂O₃ NTs electrodes were evaluated by degradation of azo dye. The significant PEC and PC performance indicated that the α-Fe₂O₃ NTs electrodes were an effective photoelectrode under visible light and simulated solar light illumination.