Controllable construction of ZnFe2O4-based micro-nano heterostructure for the rapid detection and degradation of VOCs

Micro-nano heterogeneous oxides have received extensive attention due to their distinctive physicochemical properties. However, it is a challenge to prepare the hierarchical multicomponent metal oxide nanomaterials with abundant heterogeneous interfaces in a controllable way. In this work, the effective construction of the heterogeneous structure of the material is achieved by regulating the ratio of metal salts under thermal solvent condition. Three-dimensional spheres (ZnFe 2 O 4 ) constructed by zero-dimensional ultra-small nanoparticles , in particular three-dimensional hollow sea urchin spheres (ZnO/ZnFe 2 O 4 ) constructed by one-dimensional nanorods and three-dimensional hydrangeas (α-Fe 2 O 3 /ZnFe 2 O 4 ) assembled by two-dimensional nanosheets were obtained. The two composite materials contain a large number of heterojunctions , which enhances the sensitivity of material to volatile organic compounds gas. Among them, the α-Fe 2 O 3 /ZnFe 2 O 4 composite shows the best sensing performance for VOCs. For example, its response to 100 ppm acetone reaches 142 at 170 °C with the response time shortened to 3 s and the detection limit falling to 10 ppb. Meanwhile, the composite material presents a degradation rate of more than 90% for VOCs at a flow rate of 20 mL/min at 170 °C. In addition, the sensing and sensitivity mechanism of the composite material are studied in detail by combining GC-MS, XPS with UV diffuse reflectance tests.