Lattice expansion and oxygen vacancy of α-Fe₂O₃ during gas sensing

Identifying the nature of gas-sensing material under the real-time operating condition is very critical for the research and development of gas sensors. In this work, we implement in situ Raman and XRD to investigate the gas-sensing nature of α-Fe₂O₃ sensing material, which derived from Fe-based metal-organic gel (MOG). The active mode of α-Fe₂O₃ as gas-sensing material originate from the thermally induced lattice expansion and the changes of surface oxygen vacancy of α-Fe₂O₃ could be reflected from the further monitored Raman scattering signals during acetone gas sensing. Meanwhile, the prepared α-Fe₂O₃ gas sensor exhibits excellent gas-sensing performance with high response value (R_a/R_g = 27), rapid response/recovery time (1 s/80 s) for 100 ppm acetone gas, and broad response range (5 - 900 ppm) at 183 °C. Strategies described herein could provide a promising approach to obtain gas-sensing materials with excellent performance and unveil the gas-sensing nature for other metal-oxide-based chemiresistors.