Enhancement of photocatalytic activity in ZnO NWs array due to Fe₂O₃ NPs electrodeposited on the nanowires surface: The role of ZnO-Fe₂O₃ interface

In this work, the electrodeposition technique was explored to obtain: (i) ZnO film, (ii) ZnO microrods (ZnO MRs), and (iii) ZnO nanowires array (ZnO NWA) on a slide of indium tin oxide coated glass as substrate. The ZnO NWs were decorated with Fe₂O₃ nanoparticles (Fe₂O₃ NPs). Thus, a two-step electrodeposition method was performed. In the first step, ZnCl₂ aqueous solution was employed to rise the ZnO NWs; The molar concentration, temperature, and time were explored to understand the influence of parameters on structural properties and morphology. In the second step, the Fe₂O₃ NPs were incorporated on the surface of nanowires by electrodeposition of FeCl₃ (200 μM) aqueous solution for 1 min. This was confirmed by electron microscopy. In addition, the X-ray photoelectron spectroscopy (XPS) probed that the attachment of Fe₂O₃ NPs on ZnO NWs induced a significant increment in the density of oxygen defects. The photocatalytic activity of samples was measured by photodegradation of methylene blue (MB). Findings proved that the ZnO-Fe₂O₃ heterostructure enhanced the photocatalytic activity due to the charge transfer mechanism at the interface. The Fe₂O₃ NPs prevent the degradation of ZnO NWs across photocatalytic cycles of the MB solution, showing a reduction in the global degradation efficiency of 1.93% after 3 cycles.