Ultrasensitive room-temperature H2S sensing enabled by interfacial engineering via Bi-shared Bi2S3/BiOI heterostructures

Abstract

Non-invasive breath analysis offers a transformative approach for early disease diagnosis, yet its clinical adoption is hindered by the need for sensors that reconcile high sensitivity with low power consumption. Hydrogen sulfide (H₂S), a key biomarker for halitosis and oral disorders, typically requires high operating temperatures for reliable ultra-sensitive detection, limiting its detection through wearable sensing devices. Here, we show that atomic-level Bi₂S₃/BiOI heterostructures with Bi-shared heterointerfaces, synthesized via a partial in situ anion-exchange strategy, enable ultrasensitive room-temperature H₂S sensing. The optimized sensor exhibits a response of 2690% toward 125 ppb H₂S, an 11-fold enhancement compared to its non-in situ counterparts, and achieves a practical detection limit of 5 ppb. The Bi-shared interface significantly enhances H₂S adsorption and facilitates charge transfer, resulting in the superior H₂S sensing performance, as revealed by theoretical calculations. As a proof of concept, we demonstrate a wearable sensor capable of distinguishing simulated halitosis patients from healthy individuals. Beyond presenting a robust solution for real-time breath analysis, this generalizable interface engineering strategy lays the foundation for the rational design of next-generation low-power gas sensors.