Aluminium doping in iron oxide nanoporous structures to tailor material properties for photocatalytic applications

Abstract

In this study, metal doping of iron oxide nanostructures grown by anodization is successfully achieved by the simple cost effective technique of electrochemical doping. Structural and morphological characterizations of all the samples are done using X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy in conjunction with field-emission scanning electron microscopy, respectively. A detailed analysis of the X-ray photoelectron spectra is done for all the samples to obtain the effect of aluminium doping on the multiplet peak positions of Fe 2p and different species of oxygen. Analysis of the valence band X-ray photoelectron spectra (VB XPS) reveals a displacement of ‘valence band edge’ towards higher energy on doping. The VB XPS coupled with optical data is used for evaluating the shift in the Fermi level towards the conduction band minimum, which indicates the formation of donor defect level on doping. The reduction in band gap from 1.96 to 1.72 eV and enhanced electrical conductivity on doping are observed to produce an improvement in the photo catalytic activity for aluminium-doped nanostructures compared to undoped.