Interface-Engineered SnO2-PdO-Pd2Sn Composite: Toward High-Sensitivity Hydrogen Detection with Ultralow Detection Limit at Low Temperatures.

Traditional SnO2-based gas sensors are hindered by poor low-temperature sensitivity, slow response kinetics, and dependence on high-temperature operating conditions (200°C-500°C), limiting practical trace hydrogen-leak detection. To address this, we develop a simple and controllable two-step strategy. A Sn/Pd bimetallic precursor is first prepared via mild hydrothermal deposition, then calcined in inert argon to realize in situ phase transformation and interfacial regulation, successfully yielding an SnO2-PdO-Pd2Sn (SPO/PS) composite suitable for rapid and efficient low-temperature hydrogen detection. At 77°C and 45% RH, the SPO/PS sensor exhibits a response value of up to 28 976.56% to 2000 ppm hydrogen, which is 83.62 times that of pure SnO2 at 370°C, with response/recovery times of 1.1/184.7 s, a theoretical limit of detection (LOD) as low as 30 ppb, and outstanding selectivity for hydrogen. Even at 90% RH, its response to 2000 ppm hydrogen remains 7651.38%, and it achieves stable operation for 80 days. This work realizes synergistic structural and performance optimization of the SPO/PS system through a facile synthesis, providing a new strategy for the development of low-temperature, highly sensitive hydrogen sensors.