Wearable and Highly Sensitive Sensing Fiber Enabled by Mesoporous MXene and MXene/SnSe for Ammonia Gas and Temperature Monitoring of Firefighting Clothing

Abstract Traditional firefighting clothing plays a crucial role in protecting firefighters from burn injuries through its passive heat insulation performance. However, current firefighting garments still face a challenge in dealing with complex and changeable rescue scenarios due to their insufficient risk warning capability for firefighter safety. Herein, we propose a wearable bimodal fiber sensor with a core-sheath structure, which incorporates an engineered mesoporous Ti3C2Tx and a Ti3C2Tx/SnSe heterojunction integrated into an aramid nanofiber substrate for monitoring exposed ammonia gas and temperature in firefighting clothing. The outer shell of sensing fiber is composed of mesoporous Ti3C2Tx, featuring active edge-Ti-O sites, while the MXene and SnSe in the core layer of the sensing fiber create nanoscale Schottky junctions that facilitate an energy filtering effect. The resulting chemical resistance-type gas sensing fiber sheath provides an ultrafast response time (9 s) and high sensitivity (41.76% @ 8 ppm) in detecting NH3. Additionally, due to the energy filtering effect of the nanoscale Schottky junction between Ti3C2Tx and SnSe, the sensing fiber core exhibits high thermoelectric sensitivity (S = 560 μV K−1 from 130 to 320 °C), super-resolution (1 °C), and a wide temperature monitoring range (−20 to 320 °C). To facilitate wearable applications, the sensing signals from the monitoring system are transmitted wirelessly via Bluetooth and displayed on a smartphone, enabling multidirectional dynamic warnings for NH3 and overheating alerts in firefighting clothing. This work significantly advances the implementation of wearable gas and temperature warning sensors in firefighting clothing for enhancing firefighter safety.