Light-enhanced ultra-sensitive NO₂ gas detection using In₂O₃/MXene-based flexible sensors

In this study, we developed a highly sensitive and selective gas sensor utilizing an In₂O₃/MXene-based nanocomposite, which operates effectively at room temperature under UV irradiation. The incorporation of UV light enhances gas adsorption and desorption kinetics, resulting in a rapid and reversible resistance change upon NO₂ exposure. Unlike conventional metal oxide-based gas sensors that require high-temperature operation (typically above 200 °C), our sensor demonstrates excellent photo-activated gas sensing capabilities at room temperature, significantly reducing power consumption and enhancing practical applicability. As a flexible sensor, it maintains mechanical robustness even after being bent more than 2000 times in application, and ensures long-term stability against external stress for more than 30 days. It has also been shown to maintain high selectivity for NO₂ even in the presence of common interfering gases such as NH₃, CO, SO₂, and ethanol, which are commonly encountered in industrial and urban environments, and has been proven to maintain excellent gas detection performance even under harsh conditions such as high humidity (70 % RH) and direct water exposure. Excellent gas response with linearity was observed in the 5–100 ppb NO₂ range, and the limit of detection (LOD) was calculated to be 0.79 ppb, indicating ultra-sensitive detection performance suitable for real-world air quality monitoring.