MoS2/MoO3 heterojunctions enabled by surface oxidization of MoS2 nanosheets for high-performance room-temperature NO2 gas sensing

Transition-metal dichalcogenides (TMDs) have emerged as ideal candidates for room-temperature gas sensing due to their remarkable semiconductor properties. However, bare TMDs typically exhibit drawbacks such as low sensitivity, slow response, and low recovery speeds, which limit their applicability. In comparison to single materials, enhancing the sensing performance of the material can be achieved through the realization of heterostructures. Therefore, the key to improving the performance of metal-sulfide gas sensors lies in the controlled construction of unique heterostructures. In this work, surface heterostructures composed of molybdenum disulfide (MoS2) nanoflowers loaded with molybdenum trioxide (MoO3) enabled are realized through the surface oxidization of MoS2 nanosheets for high-performance room-temperature detection of NO2 gas. The heterostructures were easily constructed by oxidizing flower-like MoS2 using a hydrogen peroxide aqueous solution. The gas sensor based on the MoS2/MoO3 heterojunction exhibits a response of 18.9 % to 1 ppm NO2, which is nine times higher than that of the MoS2 sensor (2.1 %). Furthermore, even at a NO2 concentration as low as 50 ppb, the sensor response can reach 6.9 %. The sensor displays good repeatability and excellent selectivity. The enhanced gas-sensing performance of the MoS2/MoO3 heterostructure may result from the unique structure of MoS2 and the p-n heterojunction formed at the interfaces. The proposed design strategy and the surface heterostructure constructed in this work can provide guidance for the development of high-performance gas-sensitive materials and devices.