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.