A resistivity-Type Palladium Decorated WSe2 Device for Ultralow Concentration Hydrogen Detection

Due to the extremely small size of hydrogen atoms and the absence of molecular polarity, detecting Hydrogen gas (H₂) at the ppb level is typically challenging. Here, a resistivity-type H₂ sensor based on Pd nanoparticles decorated tungsten diselenide (WSe₂) device has been constructed. Benefiting from the inherently low background carrier concentration of WSe₂, the device enables a significant reduction in the baseline current. By implementing responsivity optimization strategies, including morphological control of Pd nanoparticles, enhancement of carrier mobility, reduction of contact resistance, and optimization of the operating temperature, the sensor achieved a record-high responsivity of 628% (at 1000 ppm H₂) at approximately 65 °C, with a benchmark detection limit (LOD) of 10 ppb. This performance represents the highest level reported to date for H₂ sensors based on 2D materials. The device also exhibited excellent selectivity and stability. In addition, first-principles calculations reveal that the H₂ sensing mechanism is based on the modulation of carrier concentration in WSe₂ by Pd nanoparticles through the electron transfer process at the Pd/WSe₂ interface in H₂ environment. In a broader perspective, our work suggests strategies and methodologies for fabricating and optimizing high-performance H₂ sensors based on 2D materials and other semiconductor-based materials.