Biomimetic fabrication of α-Fe₂O₃ with hierarchical structures as H₂S Sensor

A facile sol–gel method is developed for the fabrication of α-Fe₂O₃ with quasi-honeycomb like structures inherited from Papilio paris butterfly wings. The exquisite hierarchical architecture is faithfully maintained in α-Fe₂O₃ from the skeleton of butterfly wings at the levels from macro to nano-scales. When used as a chemical sensor, the obtained α-Fe₂O₃ replica (P-α-Fe₂O₃) showed a much higher performance than that of the compared α-Fe₂O₃ nanoparticles synthesized under the same condition without biotemplate (S-α-Fe₂O₃). The P-α-Fe₂O₃-based sensor has a sensitivity of 19.2–50 ppm H₂S, which is four times more than that of S-α-Fe₂O₃, accompanied by a rapid response/recovery time within 1/10 s even at a relatively low working temperature of 180 °C. Compare to the S-α-Fe₂O₃, surface area of which cannot be detectable, the high sensing feature of P-α-Fe₂O₃ would be attributed to the relatively high-specific surface area 24.12 m²/g thus fabricated together with the unique 3D-network structures, which provide channel for the diffusion of H₂S. This strategy is expected to be used in fabrication of other kinds of metal oxide with unique structures for the potential application in gas sensor.