Microstructure and photocatalytic properties of polyimide/heterostructured NiO–Fe2O3–ZnO nanocomposite films via an ion-exchange technique

Abstract

A series of NiO–Fe₂O₃–ZnO layers on double surfaces of polyimide (PI) film have been fabricated by alkaline-induced chemical modification and ion-exchange reaction. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) analyses confirmed the successful formation of the heterostructured NiO–Fe₂O₃–ZnO layers on PI surfaces. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the NiO–Fe₂O₃–ZnO nanoparticles were dispersed uniformly on the PI surface and exhibited an interesting mesh-shaped morphology. The UV-vis absorption results demonstrated that the PI/heterostructured NiO–Fe₂O₃–ZnO nanocomposite exhibited wide visible-light photo absorption in the 400–740 nm range. Moreover, the PI/heterostructured NiO–Fe₂O₃–ZnO nanocomposite films possessed excellent mechanical properties and acceptable adhesion, and they exhibited superior photocatalytic activity compared with PI/ZnO nanocomposite film toward the degradation of dyes under solar irradiation. The degradation rate of methyl orange over PZNF-3 after 240 min simulated solar light irradiation reached an optimum value 96.2%. The improved photocatalytic activity of the PI/heterostructured NiO–Fe₂O₃–ZnO could be mainly attributed to the efficient separation of photoinduced electrons and holes of the photocatalysts, caused by the vectorial transfer of electrons and holes among ZnO, NiO and Fe₂O₃. This study introduces a new class of promising sunlight-driven photocatalytic nanocomposites with outstanding comprehensive performance.