An in-depth photoluminescence investigation of charge carrier transport in ZrO2|V2O5 type I junction: Probing the production of hydroxyl radicals

Abstract

The determination of the band edge positions turns out to be of particular importance in different fields. We present a comparison of different approaches for the determination of the band edge alignment. For this purpose, we suggested studying the ZrO2|V2O5 heterojunction. The structural properties investigated by means of X-ray diffraction (XRD) revealed the formation of pure V2O5 with an orthorhombic structure. The resulting ZrO2, however, exhibits two different phases (monoclinic and tetragonal). Based on the absorption spectra, the near-band edges for V2O5, ZrO2, and ZrO2|V2O5 were found to be 2.07, 4.9, and 2.12 eV, respectively. The corresponding band gap values determined by the Tauc method were found to be 2.32, 5.16, and 2.35 eV, respectively. The down-conversion photoluminescence (PL) spectra of pure and junctioned materials are discussed in detail. The up-conversion in ZrO2 revealed its band gap value (∼5.14 eV), which is very close to the one obtained by the Tauc method (∼5.16 eV). The band gap alignment of the ZrO2|V2O5 heterojunction was determined using Sanderson method and experimentally using X-ray photoelectron spectroscopy (XPS). In this work, we propose an In-depth photoluminescence study for the confirmation of the type of heterojunction by probing the hydroxyl radical (HO•) production.