Atomically Bridged Ti─O─Sn Heterointerfaces and Built‐in Electric Field Enable a TENG‐Powered NH ₃ Sensor with ppb‐Level Detection for Marine Environments

Ammonia (NH 3 ) is increasingly viewed as a next‐generation carbon‐free fuel; however, its high volatility and toxicity make continuous, energy‐autonomous leak monitoring essential for safe deployment. Here, we present a fully self‐powered ammonia sensing system that integrates broadband vibration energy harvesting with atomic‐scale interface engineering. A stacked triboelectric vibration energy harvester (T‐VEH) efficiently converts stochastic mechanical vibrations from ship engines into continuous electrical power (6.423 mW kg −1 ), maintaining stable output over 200 h of operation. This sustainable energy source drives an MXene‐SnO 2 heterostructured sensor, in which atomic Ti─O─Sn bridges and abundant oxygen vacancies create a strong built‐in electric field that accelerates charge transfer and O 2 activation, achieving ppb‐level (5.17 ppb) NH 3 detection at room temperature with high selectivity. Field deployment aboard ammonia‐fueled test vessels demonstrates real‐time, wireless spatial mapping of NH 3 concentration under realistic vibration and humidity conditions, without external power input. By integrating ambient‐energy transduction with atomic‐level interface design, this vibration‐to‐sensing architecture provides a scalable framework for autonomous chemical monitoring, transforming otherwise wasted mechanical energy into intelligent safety power for next‐generation maritime infrastructure.