Ultrasensitive Room-Temperature Detection of Nitrogen Oxides Using Bi₂S₃ Derived from a Bismuth-Based Metal-Organic...

Nitrogen oxides (NO_X) pose significant risks to human health and the environment even at low concentrations, which makes their detection at trace levels increasingly important. However, the development of high-performance gas sensors operating at room temperature for monitoring nitrogen oxides (NO_X) remains a significant challenge, primarily due to the poor sensitivity and selectivity of most sensing materials under ambient conditions. Herein, we report a bismuth-based metal-organic framework (Bi-MOF) template strategy to synthesize orthorhombic Bi₂S₃ with a fiber-like architecture for exceptional NO_X detection. The Bi-MOF precursor was synthesized via a solvothermal route and subsequently converted to Bi₂S₃ through sulfidation. FTIR, XPS, and BET analyses were carried out to investigate the surface chemistry and textural properties of the sensitive material. The as-prepared Bi₂S₃-based sensor demonstrates extraordinary responses to trace-level NO_X gases at room temperature, exhibiting a colossal response of 655.65% to 0.5 ppm NO₂ and a significant response of 301.42% to 5 ppm NO, accompanied by fast response/recovery times and remarkably low detection limits (0.04 ppb for NO₂ and 0.099 ppb for NO). The device also responds to N₂O, which is chemically stable and resistant to redox reactions, indicating broad sensitivity within the NO_X family. Beyond high sensitivity, the sensor boasts superior selectivity toward NO_X, strong signal-to-noise ratios, and reliable performance under humid conditions, along with moderate long-term stability. This work not only presents a premier Bi₂S₃-based chemiresistive sensor for room-temperature NO_X detection but also validates MOF-derived synthesis as a potent pathway for engineering highly efficient semiconductor gas sensing materials.