Interface‐Engineered SnO ₂ ‐PdO‐Pd ₂ Sn Composite: Toward High‐Sensitivity Hydrogen Detection with Ultralow Detection Limit at Low Temperatures

ABSTRACT Traditional SnO 2 ‐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 SnO 2 ‐PdO‐Pd 2 Sn (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 SnO 2 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.