In₂O₃ Nanoparticles Decorated ZnO Hierarchical Structures for n-Butanol Sensor

In2O3 nanoparticles decorated ZnO hierarchical structures with excellent n-butanol-sensing performance were successfully fabricated by the one-pot sol–gel method. The formation process of the unique In2O3–ZnO hierarchical structure was investigated through experiments. The addition of indium was a crucial factor for the morphology and structure of the final product. The influence of the addition of indium on the sensor properties of the In2O3–ZnO hierarchical structure was examined systematically. The optimum indium–zinc ratio was 1:3. Sensor responses of the In2O3–ZnO (1:3) heterostructures toward 10 and 100 ppm n-butanol reached 18 and 218.3 at 260 °C. The response–recovery times toward 10 ppm n-butanol were 1 and 5 s. The gas-sensing mechanism was investigated based on the X-ray photoelectronic spectroscopy, photoluminescence spectroscopy, electron paramagnetic resonance spectroscopy, and UV–vis diffuser reflectance spectroscopy analyses. The improved gas-sensing performance of In2O3–ZnO was ascribed mainly to the unique microstructure and the surface decoration by In2O3 nanoparticles.