Mesoporous anodic α-Fe₂O₃ interferometer for organic vapor sensing application

In this work, we reported the utilization of mesoporous α-Fe₂O₃ films as optical sensors for detecting organic vapors. The mesoporous α-Fe₂O₃ thin films, which exhibited obvious Fabry-Perot interference fringes in the reflectance spectrum, were successfully fabricated through electrochemical anodization of Fe foils. Through monitoring the optical thickness of the interference fringes, three typical organic species with different vapor pressures and polarities (hexane, acetone and isopropanol) were applied as probes to evaluate the sensitivity of the α-Fe₂O₃ based interferometric sensor. The experiment results showed that the as-synthesized mesoporous α-Fe₂O₃ interferometer displayed high reversibility and stability for the three organic vapors, and were especially sensitive to isopropanol, with a detection limit of about 65 ppmv. Moreover, the photocatalytic properties of α-Fe₂O₃ under visible light are beneficial for degradation of dodecane vapor residues in the nano-pores and refreshment of the sensor, demonstrating good self-cleaning properties of the α-Fe₂O₃-based interferometric sensor.