Ultrathin 2D NbWO₆ Perovskite Semiconductor Based Gas Sensors with Ultrahigh Selectivity under Low Working Temperature

Abstract Hydrogen sulfide (H₂S) detection with high selectivity and low working temperature is of great significance due to its strong toxicity both to the environment and to humans and also as an endogenous signaling molecule existing in various physiological processes. 2D perovskites with high carrier mobility are promising candidates for gas sensing; however, the development of stable and nontoxic 2D perovskites nanosheets still remains a challenge. Herein, 2D all‐inorganic NbWO₆ perovskite nanosheets with thicknesses down to 1.5 nm are synthesized by liquid exfoliation, and the gas‐sensing performance based on these ultrathin nanosheets is investigated. A few‐layer NbWO₆‐based sensor exhibits fast H₂S sensing speed (<6 s) with high selectivity and sensitivity (S = 12.5 vs 50 ppm) at low temperature (150 °C). A small variation of H₂S concentration (<0.5 ppm) can be detected with a fully reversible resistance signal. This work sheds light on the development of high‐performance gas sensors working in ambient conditions based on low‐dimensional, nontoxic, and wide‐bandgap perovskite semiconductors. The high carrier mobility, ultrathin structure, and soft nature make this type of 2D perovskite semiconductor an ideal material candidate for the fabrication of flexible, transparent, and wearable sensing devices in the future.