Photoelectrochemical properties of anodic iron oxide layers

Abstract

As a result of anodization, nanostructured iron oxide was obtained in an unstirred ethylene glycol-based solution with 0.2 M NH4F and 0.5 M H2O. The morphology of the obtained materials was characterized and correlated with the applied potential used for electrosynthesis. The performed XRD analysis enabled the identification of iron oxide crystalline phases (hematite, magnetite) obtained as a result of material annealing at 400 °C. The correlations between oxide layer thicknesses, maximal IPCE values obtained at the potential of 0.3 V vs. SCE, and estimated donor densities for anodic samples formed at different anodizing potentials were observed. All the tested electrodes are capable to generate an anodic photocurrent in the wavelength range from 200 to about 700 nm. It should be mentioned that the studied materials possess a narrow band gap energy (∼2.2 eV), which allows efficient visible light absorption.