Rare Earth Single Atoms Steering Hydrogen Spillover Over Pd/WO₃ Toward High‐Efficiency H₂ Sensor at Near Room Temperature

Metal oxide semiconductor (MOS) supported Pd materials are potential candidates for H 2 sensors, while effective H 2 detection at near room temperature remains a great challenge owing to the difficulty of hydrogen migration from Pd at low temperature. Herein, guided by theoretical calculations, rare earth single atoms doping Pd nanoparticles supported on WO 3 nanorods with tunable work function differences (ΔФ) and oxygen vacancies are precisely developed to improve H 2 sensing performances. The resultant Ce‐Pd/WO 3 presents the highest response of 31.3 toward 50 ppm H 2 , showing 6 times improvement over the Pd/WO 3 , which realizes the trace and fast detection of H 2 . Density functional theory results reveal that the energy barrier of hydrogen migration and the formation energy of oxygen vacancy decrease after introducing rare earth single atoms, and Ce‐Pd/WO 3 with the lowest ΔФ exhibits the most facile hydrogen spillover and desorption. The in situ spectra characterization and hydrogen spillover experiments further demonstrate the highly improved hydrogen migration over the Ce‐Pd/WO 3 . Significantly, the real‐time monitoring application of the Ce‐Pd/WO 3 device for hydrogen leak (0.1 V/V%) in Al‐air batteries is also verified. This work can shed light on the development of a high‐efficiency H 2 sensor via the precise modulation of work functions.