MoS2–MoSe2 nanoflakes-based n–n heterojunction toward highly sensitive and selective room-temperature NO2 gas sensor

The present research reports the controlled fabrication of MoS2–MoSe2 hybrid nanostructures utilizing DC magnetron co-sputtering technique for highly selective and sensitive room-temperature (RT) NO2 detection. Among the optimized sensing thin films, the MoS2–MoSe2 sensor with a precisely engineered thickness of ∼350 nm demonstrates an exceptional sensor response of ∼61.3% toward 0.7 ppm NO2 at RT, coupled with a rapid response/recovery time of ∼77/87 s. This superior sensitivity of the MoS2–MoSe2 sensor is attributed to the abundant adsorption sites, the synergistic effects of MoS2–MoSe2 heterostructure, efficient charge transfer dynamics, and the unique n–n heterojunction band alignment, which collectively enhance carrier modulation and gas interaction kinetics. Additionally, the sensor delivers remarkable repeatability over 21 consecutive cycles, long-term operational stability exceeding 80 days, and outstanding selectivity toward NO2 against potentially interfering gases, underscoring its reliability for real-world applications. Thus, the MoS2–MoSe2 nanocomposite sensor emerges as a promising candidate for next-generation NO2 gas sensing, offering a robust platform for real-time air quality monitoring and environmental safety applications.