Room-Temperature Flexible CNT/Fe₂O₃ Film Sensor for ppb-Level H₂S Detection

Carbon nanotubes (CNTs) had room temperature response, large surface area, and excellent mechanical properties, making them favorable for the design of flexible, wearable, and portable gas sensors. However, CNTs were lacking in response and selective response to different gases, such as H₂S. Here, we demonstrated a flexible H₂S ppb-level gas sensor based on a carbon nanotube/amorphous Fe₂O₃ (CNT/Fe₂O₃) film at room temperature, which was fabricated via a simple one-step solvent-thermal method. The CNT/Fe₂O₃ film gas sensor exhibited a high selective response to H₂S (with a response of 55.1% to 100 ppb H₂S), rapid reversible response at room temperature (with a response time of ∼127 s to 100 ppb H₂S), and low limit of detection to about 2 ppb. Additionally, the CNT/Fe₂O₃ film maintained good sensing performance under various bending conditions and could be further fabricated into the fiber gas sensor device via wet stretching, retaining response at the ppb level (with a response of 18.6% to 100 ppb H₂S). This research on a flexible gas sensor device based on the CNT film/fiber opened up new possibilities for wearable portable electronic device applications.