Spontaneous polarization field-enhanced charge separation for an iron oxide photo-catalyst

This study focuses on the morphological effects of zinc oxide nanostructures on the charge separation of iron oxide/zinc oxide nanocomposite materials in a photoelectrochemical (PEC) cell. More specifically, the effect of a spontaneous polarization field from the zinc oxide nanosheet structure on the photocatalytic charge separation was investigated for the first time. Two different morphologies of zinc oxide nanosheets (NSs) and nanorods (NRs) were produced through an electrochemical approach followed by spin coating techniques to decorate the nanostructures with iron oxide nanoparticles. The morphology and composition of the nanocomposite systems were characterized using SEM, XRD and EDS. The visible light absorbance of the nanocomposite materials was confirmed by diffuse reflectance spectroscopy (DRS). The photoresponse of the composite material was studied using a potentiostat under visible light irradiation, and it was found that the NSs produced a current density of 1.5 μA cm^-2, which was four times larger than that of the NRs. These findings were explained by the existence of a strong spontaneous polarization field in the nanosheet structure. The combination of iron oxide on the zinc oxide NSs was found to be a better choice in photocatalytic water splitting.