A Self-Powered, Ultrasensitive, and Flexible Gas Sensor Based on Tough and Degradable Leather Hydrogel for Portable Wireless Trace H₂S Detection

Hydrogen sulfide (H₂S), a toxic gas and key biomarker, is crucial to environmental safety and human health, yet existing sensors struggle with real-time, portable detection at trace levels. Here, we report a cost-effective, flexible, self-powered H₂S sensor with outstanding performance at room temperature, constructed using a galvanic cell structure and leather hydrogel as the electrolyte. The degradable, tough leather hydrogel confers flexibility, mechanical robustness, and eco-friendliness on the sensor. Upon gas adsorption, monitoring the electrode potential change induced by interfacial charge transfer enables a pronounced response even to trace concentrations. The sensor delivers exceptional sensitivity, with a detection limit down to 0.109 ppb—the lowest among reported electrochemical H₂S sensors—while also exhibiting excellent selectivity, stability, and repeatability. Performance can be further enhanced by serially connecting, and its self-powered nature enables visual detection of H₂S concentration. Furthermore, a wireless sensing system based on Bluetooth and cloud technology is developed, validating the sensor's practical application potential in periodontitis grading diagnosis, meat spoilage monitoring, and H₂S leak detection. This work provides a novel strategy for the development of high-performance, cost-effective, portable H₂S sensors and holds great promise for applications in environmental monitoring, health diagnostics, and smart sensing systems.