Synthesis and characterization of an ultra-thin BiOCl/MXene heterostructure for the detection of NO2 at room temperature with enhanced moisture resistance

Two-dimensional ultrathin MXenes (Ti3C2Tx) have gained crucial attention in the field of gas sensing owing to their unique chemical and physical properties. Here, a hot-injection method is reported to uniformly decorate BiOCl nanosheets on the surface of an ultrathin MXene to synthesize a BiOCl/MXene binary heterostructure. The interfacial contacts between the components promote carrier migration and space charge separation. The prepared BiOCl/Mxene sensor has a unique structure, excellent homogeneity, and good electronic performance, maintaining a high response of 30.54 at high humidity (RH = 80%) with detection limits as low as 50 ppb. Under dry conditions (RH = 25%) the sensor displayed an over 4.6 times higher response than that of the pure BiOCl material and showed a short response time of only 3.15 s, while the detection limit reached 30 ppb. The sensor retained long-term stability over 6 consecutive weeks accompanied by good selectivity towards NO2 gas.