Zhaorui Zhang,Haiying Du,Huashuai Hu,Dongchen Tan,Jinkui Chu,Minghui Yang
Two-dimensional transition metal carbon nitrides (MXenes) are a prominent class of functional materials with significant potential for sensing applications. However, their conventional charge transfer mechanisms pose limitations for detecting nitrogen dioxide (NO 2 ). In this study, we successfully design-synthesized potassium titanate (KTO) nanoribbons by oxidizing and alkalizing monolayer Ti 3 C 2 T x MXene, targeting room-temperature NO 2 detection. The Ti 3 C 2 T x -derived KTO exhibited exceptional selectivity for NO 2 , achieving a remarkable response of 649.2 % for 50 ppm NO 2 , which is 550 times higher than that of the Ti 3 C 2 T x sensor (1.18 %). Additionally, the sensor demonstrated a detection limit as low as 5 ppb at room temperature, along with rapid response (1 s) and recovery times (2 s), and excellent linearity. Computational analysis showed that the abundant OH groups on the KTO surface contribute to strong selective adsorption (2.79 |eV|) and efficient electron transfer (0.91 |e|) for NO 2 . The unique proton conduction mechanism of KTO further reduced the activation energy for proton transport, enhancing NO 2 sensing performance. This study highlights the potential of Ti 3 C 2 T x -derived KTO nanomaterials for advanced room-temperature NO 2 detection and sensor technology development.
The development of multifunctional hydrogels with enhanced mechanical, electrical, and electromagnetic properties has become a key focus in various advanced applications, including wearable electronics, strain sensors, and electromagnetic interference (EMI) shielding. However, challenges remain in achieving a balanced integration of stretchability, conductivity, and broadband microwave absorption within a single material. This study addresses these limitations by introducing a novel dual-crosslinked Ti₃C₂Tx MXene-based hydrogel designed for wearable sensor and EMI shielding applications. The PVA/MXene/PSS hydrogel is synthesized via a freeze-thaw crosslinking method to create a three-dimensional (3D) conductive network. Water retention and conductivity are enhanced through the synergistic effect between sodium chloride (NaCl) and formic acid (HCOOH), addressing key challenges such as water evaporation and MXene dispersion. The resulting hydrogel exhibits impressive mechanical stretchability (369% tensile strain), long-term stability (6000 s under 25% strain), and ultra-high strain sensitivity with a minimum detectable strain of 1%. It demonstrates gauge factors of 0.78 and 0.51 in the transverse and longitudinal directions for strains below 50%, respectively, and 0.28 and 0.37 for strains between 50% and 100%. Moreover, it demonstrates exceptional broadband microwave absorption with a peak reflection loss of −55.5 dB at 10.73 GHz, with an effective absorption bandwidth of 6.34 GHz. The combination of excellent mechanical, electrical, and microwave properties, along with superior stretchability and durability, makes this hydrogel a promising candidate for next-generation wearable sensors, flexible electronics, and electromagnetic interference shielding.
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