Controllable Synthesis of Zn-Doped α-Fe₂O₃ Nanowires for H₂S Sensing

One-dimensional Zn-doped α-Fe₂O₃ nanowires have been controllably synthesized by using the pure pyrite as the source of Fe element through a two-step synthesis route, including the preparation of Fe source solution by a leaching process and the thermal conversion of the precursor solution into α-Fe₂O₃ nanowires by the hydrothermal and calcination process. The microstructure, morphology, and surface composition of the obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that the formation process of α-Fe₂O₃ is significantly influenced by the introduction of Zn²⁺. The gas sensing measurements indicated that the sensor based on 1% Zn-doped α-Fe₂O₃ nanowires showed excellent H₂S sensing properties at the optimum operating temperature of 175 °C. Notably, the sensor showed a low H₂S detection limit of 50 ppb with a sensor response of 1.5. Such high-performance sensing would be ascribed to the one-dimensional structure and high specific surface area of the prepared 1% Zn-doped α-Fe₂O₃ nanowires, which can not only provide a large number of surface active sites for the adsorption and reaction of the oxygen and H₂S molecules, but also facilitate the diffusion of the gas molecules towards the entire sensing materials.