A Wearable Acetone Gas Sensor Enabled by Quantum Dot-Sensitized Flower-like Ti ₃ C ₂ T _<i>x</i> for Metabolic Monitoring

Acetone, a key biomarker for metabolic processes, and its excessive levels can cause ketosis or even ketoacidosis, posing significant risks to human health. Therefore, real-time acetone detection is crucial for noninvasive health monitoring. Ti₃C₂T_<i>x</i>-based sensors demonstrated considerable potential for detecting VOC gases but often face issues with sensitivity and environmental stability. In this work, a flower-like Ti₃C₂T_<i>x</i> anchored with MoS₂ quantum dots (F-Ti₃C₂T_<i>x</i>/MoS₂) was proposed for the first time to achieve accurate acetone detection even under high humidity conditions. The unique flower-like morphology significantly increased the surface area of Ti₃C₂T_<i>x</i> and amplified its electron scattering effects. MoS₂ modification not only reduced the content of Ti defects but also formed a passivation layer, providing a novel approach to address the inherent oxidation issue of Ti₃C₂T_<i>x</i>. Moreover, the p-n heterojunction between F-Ti₃C₂T_<i>x</i> and MoS₂ promoted charge separation, enabling high-performance acetone detection. Compared with intrinsic Ti₃C₂T_<i>x</i>, a 4.83-fold enhancement in response to 25 ppm of acetone was achieved by using a F-Ti₃C₂T_<i>x</i>/MoS₂ sensor with an ultralow detection limit of 163.2 ppb and a rapid response/recovery time (26.0 s/33.7 s). When integrated into a portable breath analyzer, the sensor demonstrated accurate acetone monitoring under atmospheric conditions, underscoring its potential for real-time and noninvasive health diagnostics.