Ordered Anti-Restacking Three-Dimensional Ti3C2Tx MXene Networks on Silicon Microcone Arrays via Template-Directed Assembly for Highly Efficient Room-Temperature Ammonia Sensing.

The realization of room-temperature, low-power chemiresistive ammonia (NH3) sensors is highly desirable yet remains a formidable challenge, primarily hindered by the high activation energy of conventional metal oxides and the severe nanosheet restacking of emerging 2D MXene. Here, we propose a morphology-templated assembly strategy to construct an antirestacking, highly accessible 3D Ti3C2Tx MXene sensing network using ordered silicon microcone arrays as 3D scaffolds. This architectural design effectively prevents the face-to-face self-assembly of 2D MXene sheets, establishing unobstructed vertical channels for rapid gas molecule transport and maximizing the exposure of active terminal sites. Consequently, the optimized room-temperature sensor delivers an exceptional gas-sensing performance, featuring a broad dynamic range (100-10,000 ppm) and a 10.2-fold response enhancement toward 10,000 ppm NH3 compared to the device without microcones. Moreover, the sensor exhibits rapid signaling kinetics (120 s), excellent selectivity, and durable reliability. This work offers a controllable three-dimensional Ti3C2Tx sensing-layer design for low-power, room-temperature NH3 leakage monitoring.