Ultrastable Photoactive Halide Perovskite Nanocrystal-Sensitized SnO2 Nanorods for Room-Temperature NO2 Detection

Abstract

Metal oxide (MOx)-based NO2 gas sensors typically require high temperatures or ultraviolet light, limiting their practical use. To enable visible-light activation at room temperature, efficient and stable photosensitizers should be integrated with nanostructured MOx hosts. Halide perovskites (HP) have gained attention as promising visible-light photosensitizers due to their excellent optoelectronic properties. However, the structural stability of HP remains a critical barrier to practical implementation, necessitating robust passivation strategies that ensure both long-term durability and efficient interfacial charge transport. Herein, we present a novel strategy in which CsPbBr3 nanocrystals (NCs) are encapsulated with an ultra-thin (similar to 2 nm) SiO2 shell and integrated onto structurally engineered porous SnO2 nanorods (NRs). The sensor exhibits 13-fold and 30-fold enhancement in response to 10 ppm NO2 gas under green light, compared to dark conditions and planar SnO2, respectively. Furthermore, the SiO2 encapsulation enables the CsPbBr3 NCs to maintain long-term stability as photosensitizers for over 5 weeks, which is an unprecedented duration among visible light-activated gas sensors. Our results demonstrate the synergistic effect of surface defect passivation and nanostructure engineering, providing a robust design strategy for realizing highly stable and high-performance gas sensors based on HP photosensitizers and nanostructured MOx hosts under visible light.