Hierarchical α-Fe₂O₃/NiO composites with a hollow structure for a gas sensor

Hierarchical α-Fe₂O₃/NiO composites with a hollow nanostructure were synthesized by a facile hydrothermal method. The structures and morphologies of the composites were investigated by different kinds of techniques, including X-ray diffraction, field-emission electron scanning microscopy, transmission electron microscopy, and energy dispersive spectroscopy. Hierarchical α-Fe₂O₃/NiO composites were fabricated by growing the α-Fe₂O₃ nanorods on the surfaces of porous NiO nanosheets with a thickness of ∼12 nm. The gas sensing properties of hierarchical α-Fe₂O₃/NiO composites toward toluene were investigated using a static system. The response of α-Fe₂O₃/NiO composites to 100 ppm toluene was ∼18.68, which was 13.18 times higher than that of pure NiO at 300 °C. The enhanced response can be attributed to heterojunction. Meanwhile, the rapid response and recovery characteristics were observed because of the porous hollow structural characteristics and catalytic actions of α-Fe ₂O₃ and NiO.