Fabrication and characterization of α-Fe₂O₃/CuO heterostructure thin films via dip-coating technique for improved photoelectrochemical performance

Abstract

In this work, a heterostructure-based thin film combining n-type α-Fe 2 O 3 with p-type CuO was fabricated by a dip-coating technique, the heterostructure was fabricated on fluorine-doped tin oxide (FTO) glass substrate. The synthesised sample was characterised by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-vis). XRD, FTIR, Raman, and XPS reveal the successful synthesis of α-Fe 2 O 3 /CuO composite and confirm the existence of hematite (α-Fe 2 O 3 ) and tenorite (CuO) phases in the heterostructure. AFM reveals the growth of CuO crystals in the heterostructure with superficial intermingled pointy shape, different than its pristine topography. The SEM images show that the α-Fe 2 O 3 /CuO heterostructure thickness was ∼880 nm. The optical band gap energies estimated from the optical transmittance spectra were 2.15, 2.00 and 1.77 eV for α-Fe 2 O 3 , CuO and α-Fe 2 O 3 /CuO heterostructure, respectively. The photoelectrochemical photocurrent effects (J-V curves) for the heterostructure were measured in a three-electrode cell in the dark and under illumination. The photocurrent density for heterostructure was improved mainly attributed to the enhanced visible light absorption, efficient charge carriers separation and transfer between α-Fe 2 O 3 and CuO.

Synergistic Effect of Iron and Copper Oxides in the Removal of Organic Dyes Through Thermal Induced Catalytic Degradation Process

“…The high-resolution spectrum for Cu was depicted in Fig. 6c, and the peaks at 953.5 and 933.27 eV, is attributed to Cu 2p 1/2 and Cu 2p 3/2 of Cu 2+ , respectively [30,35]. This confirms the presence of CuO in the nanocomposite.…”

“…XPS was performed on K-ALPHA (Themo Fisher Scientific, USA) employing monochromatic X-ray Al K-α radiation "with a spot size of 400 µm, at pressure 10 -9 mbar with full spectrum pass energy 200 eV and at narrow spectrum 50 eV". The pH PZC , or point of zero charge, of the nanocomposite, is identified as described previously [30]. In brief, several Erlenmeyer flasks were filled with 0.01 M NaCl solutions (50 mL).…”

“…The α-Fe 2 O 3 -CuO was swiftly extracted from the reaction solution using an external magnet. The optical band gap (E g ) is related to the absorption coefficient (α) and photon energy (hυ) by the Tauc equation αhυ = A (hυ-E g ) n , where A is a constant, and n is an index that varies depending on the mechanism of interband transitions, with n = 2 or 1/2 referring to indirect or direct transitions, respectively [30]. The E g value of α-Fe 2 O 3 -CuO is obtained from the intersection of the extrapolation of the linear part of the curve (Fig.…”

PHYSICAL PROPERTIES OF NOVEL α-Fe2O3/NiO HETEROSTRUCTURES THROUGH IMMERSION/ SOL–GEL SPIN COATING METHOD: DIFFERENT DEPOSITION NUMBERS OF NiO LAYER

“…More precisely, the absorption edge is in the visible region. Considering that most of the visible light occupies the solar spectrum, these -Fe2O3/NiO heterostructures can be exposed to maximize the use of sunlight [11,16]. From the absorption spectrum, it can be perceived that the range of optical bandgap is estimated between 1.60 and 1.9 eV, which is the highest optical bandgap when 3-layer NiO was used, while the lowest bandgap was achieved when 5-layer NiO was used.…”

“…Zhao et al constructed the heterojunction of TiO2-NiO using the hydrothermal method for efficient hydrogen generation and lignin photoreforming [10]. Pastrana et al fabricated α-Fe2O3/CuO heterostructure-based thin film via a dip-coating approach for improved photoelectrochemical performance [11].…”