Hierarchical and Hollow Fe₂O₃ Nanoboxes Derived from Metal–Organic Frameworks with Excellent Sensitivity to H₂S

Hierarchical and hollow porous Fe₂O₃ nanoboxes (with an average edge length of ∼500 nm) were derived from metal-organic frameworks (MOFs) and the gas sensing characteristics were investigated. Sensors based on Fe₂O₃ nanoboxes exhibited a response (resistance ratio) of 1.23 to 0.25 ppm (ppm) hydrogen sulfide (H₂S) at 200 °C, the response/recovery speed is fast and the selectivity to H₂S is excellent. Remarkably, the sensor showed fully reversible response to 5 ppm of H₂S at 50 °C, demonstrating its promise for operating at near room temperature, which is favorable for medical diagnosis and indoor/outdoor environment monitoring. The excellent performance of the Fe₂O₃ nanoboxes can be ascribed to the unique morphology with high specific surface area (SSA) and porous nanostructure.