Formation of Nanoporous Bi₂Se₃ by Selenization of Bismuth Metal–Organic Frameworks for Highly Sensitive and Selective NO₂ Sensing at Room Temperature

The development of high-performance and low-operating-temperature gas sensors is critical for real-time environmental and industrial process monitoring applications. In this study, we report the synthesis and application of a bismuth-based metal–organic framework (Bi-MOF)-derived Bi 2 Se 3 sensor for the detection of NO 2 at room temperature. Bi 2 Se 3 was synthesized through a controlled selenization process that resulted in synergistic effects between Bi-MOF and Bi 2 Se 3 . The changes in morphology and surface physicochemical properties caused by the selenization process led to the tunability of the NO 2 gas sensing properties. The Bi-MOF-derived Bi 2 Se 3 sensitive materials were characterized using XRD, SEM, transmission electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and BET to analyze their morphology, composition, pore structures, intensity of Se vacancies, and surface properties. The gas sensing performances were assessed under various NO 2 concentrations, evaluating the sensitivity, selectivity, and resistance to humidity. Our findings show that the Bi 2 Se 3 sensor exhibits excellent sensitivity and selectivity toward NO 2 at room temperature. The best sensor showed a response of 32.1% toward 0.5 ppm of NO 2 with a response/recovery time of 60.1/365.4 s, making it a promising candidate for NO 2 monitoring. This study provides significant insights into the potential of Bi-MOF-derived Bi 2 Se 3 materials in gas sensing, laying the groundwork for further research to optimize these sensors for practical applications.