Ti₃C₂T<i>_x</i> MXene Functionalized via Boron Doped MoS₂ Quantum Dots: A Synergy of Heterojunctions and Doping Effect Enabling Ultrasensitive SO₂ Detection at Room Temperature

AbstractThe design of mixed‐dimensional heterostructures has emerged to be a new frontier of research as it induces exciting physical/chemical properties that extend beyond the fundamental properties of single dimensional systems. Therefore, rational design of heterostructured materials with novel surface chemistry and tailored interfacial properties appears to be very promising for the devices such as the gas sensors. Here, a highly sensitive gas sensor device is constructed by employing heterostructures of boron doped molybdenum disulfide quantum dots (B‐MoS2 Qdots) assembled into the matrix of Ti3C2Tx MXene. Functionalization of MXene surface with B‐MoS2 Qdots as a result of strong electrostatic attraction leads to improved charge migration behavior, active site exposure and abundant specific surface area. As a result, the Ti3C2Tx/B‐MoS2 sensor device shows ultra‐high response (28,998.3% @ 3 ppm), ultra‐fast response rate (23.1% s−1), sub‐ppm (10 ppb lowest) detection of sulfur dioxide (SO2) gas and excellent reversibility at room temperature. Density functional theory‐based calculations indicate that enhanced SO2 sensing performance results from synergy of the 2D‐0D heterostructure formation and preferential adsorption of SO2, induced by doped boron (B) heteroatoms in Qdots. Finally, a portable and wireless SO2 monitoring system is demonstrated for real‐time detection of SO2 leakage and quantification under certain circumstances.