Epitaxial Growth of Phase-pure and Stable β-Fe2O3 Films by Pulsed Laser Deposition Method

Abstract

The metastable β-Fe₂O₃ has been less investigated due to the challenges in preparing phase-pure materials with high thermal stability. In this work, by pulsed laser deposition (PLD) method, we firstly reported the fabrication of phase-pure β-Fe₂O₃ films with crystallographic orientations of [100] and [111] on indium tin oxide (ITO)-coated yttria-stabilized zirconia (YSZ) substrates. The [100]-oriented β-Fe₂O₃ photoanode demonstrates higher photoelectrochemical (PEC) activity than the [111]-oriented counterpart for the water oxidation reaction, which yields a photocurrent density increase by a factor of 6 at 1.5 V_RHE under simulated AM 1.5G illumination. Moreover, the [100]-oriented β-Fe₂O₃ thin film (10-20 nm in thickness) shows outstanding thermal stability, with the phase transition temperature elevated to 650 °C, which is 150 °C higher than the typical value for β-Fe₂O₃ nanoparticles. This work demonstrates an effective method to prepare phase-pure β-Fe₂O₃ with high thermal stability.