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 (∼2nm) SiO2 shell and integrated onto structurally engineered porous SnO2 nanorods (NRs). The sensor exhibits 13-fold and 30-fold enhancement in response to 10ppm 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. © 2026 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH.