Novel Mixed-Phase α/γ-Fe₂O₃ Micro-Flower Assembled with Nanosheets for Enhancing Acetone Detection

Although individual γ-Fe₂O₃ and α-Fe₂O₃ have been widely fabricated for gas sensors, their mixed phase of α/γ-Fe₂O₃ might deliver excellent sensing properties. In this study, a facile solvothermal method was used to fabricate Fe-alkoxide. After thermal treatment, it was converted into γ-Fe₂O₃, α-Fe₂O₃ and their mixed-phase α/γ-Fe₂O₃ with a nanosheets-assembled flower-like structure. We studied the influence of calcination temperature on the phase and sensing properties on acetone detection. The α/γ-Fe₂O₃ which annealed at 400 °C included 18% α-Fe₂O₃ and it exhibited excellent sensing performance towards acetone compared to that of γ-Fe₂O₃ and α-Fe₂O₃. It showed a response of 353 to acetone with a concentration of 200 ppm, and a low limit of detection of 0.5 ppm at 160 °C. In addition, the change in responses with acetone concentration from 50 to 200 ppm shows a good linear relationship. Moreover, this material has good reproducibility and selectivity as well as a fast response time of 22 s and recovery time of 14 s to 200 ppm. Therefore, our mixed phase of α/γ-Fe₂O₃ possesses great prospects for acetone detection.