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

Elizabeth C Pastrana, Victor Zamora, Dunwei Wang and Hugo Alarcón

Abstract

In this work, a heterostructure-based thin film combining n-type α-Fe₂O₃ 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-Fe₂O₃/CuO composite and confirm the existence of hematite (α-Fe₂O₃) 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-Fe₂O₃/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-Fe₂O₃, CuO and α-Fe₂O₃/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-Fe₂O₃ and CuO.