3D Coral‐Like Ti ₃ C ₂ T _x MXene Heterostructures for Ultrasensitive Gas Sensing in Wildfire Monitoring

Abstract Wildfires, marked by sudden onset, destructive power, and challenging containment, pose serious threats to ecosystems, biodiversity, and economic stability, highlighting the critical need for advanced early warning technologies. Recently, two‐dimensional (2D) Ti ₃ C ₂ T _x MXene‐based heterostructures have emerged as promising gas sensing materials; however, simultaneously suppressing MXene oxidation while achieving non/low‐stacking regulation during heterojunction remains challenging. Here, an edge‐enriched co‐assembly and co‐planar nanoconfined exfoliation strategy is demonstrated to develop a Ti ₃ C ₂ T _x /cellulose nanocrystal (CNC)/MoS ₂ (TCM) nanohybrid featuring layered MXene heterojunctions and a coral‐like three‐dimensional (3D) hierarchical architecture. The edge stitching and antioxidant protection effects of CNC on Ti ₃ C ₂ T _x , synergized with the co‐planar‐mediated confinement exfoliation mechanism, yield high conductivity (29.5 Ω), ultralow noise (0.4%), and outstanding sensitivity (35.1% response to 10 ppm ammonia (NH ₃ )), and rapid response/recovery (6.7 s/2.2 s). Furthermore, a vector sensor array integrating NH ₃ detection, temperature sensing, and directional recognition is constructed, realizing multi‐parameter environmental monitoring for early wildfire detection. This work advances the development of MXene/MoS ₂ heterojunctions with 3D architectures while preserving intrinsic metallic properties, paving the way for applications in extreme environmental monitoring.