Hierarchically ordered 2D/1D Bi2O2S/Bi2S3 heterostructure enabled by topotactic transformation for ppb-level NO sensing under humid conditions

Template-guided topotactic transformation builds an ordered 2D/1D Bi 2 O 2 S/Bi 2 S 3 . • Bi 2 O 2 S/Bi 2 S 3 exhibited excellent sensitivity and a fast response to NO under high humidity. • The sensing mechanism was systematically studied at atomic and electronic scales. • Exhaled NO monitoring potential was demonstrated under breath-relevant conditions. Exhaled nitric oxide (NO) is a clinically relevant noninvasive breath biomarker associated with asthma diagnosis and management, yet its reliable detection remains hindered by the high humidity of human breath. Here, we develop a humidity-enhanced sensing strategy through template-guided topotactic transformation. The resulting hierarchically ordered 2D/1D Bi 2 O 2 S/Bi 2 S 3 (BOS/BS) heterostructure features an open nanoarchitecture, facilitating rapid gas transport and exposing active sites. The optimized BOS/BS sensor delivers a response of 37 to 1 ppm NO at room temperature under 90% RH, with response/recovery times of 9/33 s and a detection limit of 25 ppb. The response is nearly 12 times that of the single-phase BS sensor and 4 times that of the less ordered BOS/BS sensor Rather than excluding moisture, the BOS/BS heterostructure integrates interfacial charge redistribution with humidity-induced surface hydroxylation to promote NO adsorption and conversion. This work establishes a topotactic route to hierarchically ordered heterostructures for room-temperature NO sensing under high humidity and offers a materials-design strategy for breath-relevant NO sensing under moisture-rich conditions. Download: Download high-res image (165KB) Download: Download full-size image