Synthesis of hierarchical ZnO nanobelts via Zn(OH)F intermediate using ionic liquid-assistant microwave irradiation method

ZnOHF nanobelts (NBs) were synthesized under microwave irradiation in the presence of ionic liquid, 1,2,3-trimethyl-imidazole tetrafluoroborate. The ranges of width, length and thickness of the NBs are ca. 500-800 nm, several micrometers and 100 nm, respectively. Porous polycrystal ZnO NBs with hierarchical structure were obtained after careful heat treatment of the intermediate ZnOHF at 400 °C for 2 h. The structural characters of the ZnO NBs were investigated by XRD, SEM, TEM, HRTEM and XPS measurements, and their absorption and photoluminescence properties were studied as well. The characterization results support the proposed reaction mechanism that the hierarchical ZnO NBs were produced via ZnOHF intermediate and subsequent removal of one of its decomposition products, ZnF₂, by hot water. This may be a facile method to fabricate porous ZnO NBs with hierarchical structure.