Dual-channel synergistic conduction in layered potassium titanates for ppb-level H2S sensing and real-time leak localization.

H2S is a highly toxic and flammable gas, and mitigating its excessive emissions to protect the environment and human health remains a global challenge. In this study, we developed a high-performance room-temperature H2S sensor based on layered potassium titanate (KTO), achieving an ultralow detection limit of 0.5 ppb, a wide detection range of 0.5 ppb-50 ppm, rapid response/recovery (2.5/22.4 s for 1 ppm H2S) and superior stability over four months. The outstanding sensing performance arises from the dual conduction pathways in KTO, involving both surface and internal conduction. More specifically, H2S can be selectively adsorbed onto the surface hydroxyl groups of KTO, which enhances proton conduction. In parallel, charge transfer from H2S to KTO narrows the bandgap and increases the carrier concentration, thereby strengthening KTO's internal electronic conduction. To demonstrate KTO's application prospect, a multi-directional KTO-based sensor array is fabricated and deployed on an autonomous vehicle. Combined with machine learning, the system enables real-time H2S leak monitoring and spatial localization with an accuracy of up to 95%. This study highlights the broad potential of KTO-based sensors for industrial safety, environmental monitoring, and toxic gas early-warning applications, while also providing new design strategies for the development and performance optimization of gas sensors based on layered titanate materials.