Controlled synthesis of urchin-like ZnSnO3/α-Fe2O3 hierarchical hollow microspheres with enhanced acetone gas sensing properties

Acetone, as one of the volatile organic compounds, is harmful to human health. Thus, fast detection at an early stage plays a vital role. ZnSnO3 shows the merit for a wide range responsivity to VOCs, but the pure ZnSnO3 has slow response-recovery speeds. Herein, the sensors based on urchin-like ZnSnO3/α-Fe2O3 hierarchical hollow microspheres were synthesized by a simple two-step liquid-phase reaction. Porous α-Fe2O3 nanowires with lengths of about 30 nm and diameters of around 2.5 nm were densely anchored on the surface of ZnSnO3 microspheres, forming “urchin-like” geometries, which increased the specific surface area and supplied more active sites for the fast adsorption–desorption of gas molecules. An excellent gas sensing response value (14.24) and ultra-fast response-recovery times (3/8 s) have been recorded in as-obtained urchin-like ZnSnO3/α-Fe2O3 composite sensors at 200 °C. Compared with the pure ZnSnO3 and α-Fe2O3 sensors, the ZnSnO3/α-Fe2O3 sensor displayed an obvious enhancement in gas sensing properties for acetone, which can be put down to high surface area, porous nanostructure, and the synergistic effect of ZnSnO3 and α-Fe2O3.