Rational synthesis of ZnO decorated Fe hierarchical nanostructures for enhanced photocatalytic performance by long-pulse-width laser ablation of binary alloys target

Abstract Here we present a facile approach for the controllable synthesis of multifunctional ZnO decorated Fe hierarchical nanostructures, including ZnO quantum dots (QDs) decorated Fe nanowires, flocky Fe@ZnO core-shell nanospheres (Fe@ZnO CSNSs), ZnO nanospindles cluster on Fe core. The various hierarchical nanostructures composed of ZnO and unstable Fe nanoparticles (NPs) were successfully prepared in large scale via long-pulse-width millisecond laser ablation of Fe/Zn alloy target with suitable molar ratio immersed in anhydrous ethanol solution at room temperature and room pressure. In particular, the formation mechanism of flocky Fe@ZnO core-shell nanospheres (Fe@ZnO CSNSs) under laser ablation in liquid that constructed by unstable nanophase Fe core and stable phase ZnO QDs were proposed. As for the formation of such nanostructure, the condensation of Fe and Zn from the homogeneous metal nanodroplets after long-pulse-width laser ablation resulted in the first formation of unstable nanophase Fe core due to their huge gap in melting point. Then the subsequent diffusion and solidification of Zn atoms and oxidization process of Zn in the liquid media lead to the appearance of ZnO QDs outside the Fe core. The Fe@ZnO CSNSs were further used for the photocatalytic degradation of aromatic dye Rhodamine B (RhB). The results show that the Fe@ZnO CSNSs display quite good performance on the photocatalytic degradation of the RhB molecules under natural light irradiation with a power density around 100 mW/cm2 at 25 °C. The photocatalytic reduction of RhB is about 66.1%, 89.8%, and 94.1% after natural light irradiation for 5 min, 10 min and 20 min, respectively. The effective separation of photogenerated carriers due to the unique structure and absorption of organic molecules in the Fe@ZnO CSNSs together enhances the photocatalytic activity in the degradation of RhB. These multifunctional Fe@ZnO CSNSs present a promising potential for the removal of aromatic dye in wastewater and other catalytic applications.