Spillover Effect-Enhanced MEMS Calorimetric Sensor for High-Sensitivity Hydrogen Detection in Oxygen-Free Environments

Achieving high-sensitivity H₂ detection in complex enclosed environments such as oxygen-free conditions is crucial for the safe application of hydrogen energy. This work proposes a high-sensitivity MEMS (micro electromechanical system) calorimetric H₂ sensor operable in oxygen-free environments, which relies on a thermopile chip that converts the heat released from the reaction between hydrogen and Pd-based nanocatalysts into measurable voltage signals. It is found that the support has a significant influence on the reaction activity of Pd-based nanocatalysts. Compared with the carbon support like nanodiamond, the metal oxide support can not only accelerate the sensor's response speed but also significantly increase the response magnitude, which can be attributed to the presence of the hydrogen spillover effect. The optimized H₂ sensor exhibits a response amplitude twice that of pure Pd nanoparticles and a response time reduced to one-third of the latter. The optimized H₂ sensor also achieves a ppb-level detection limit and demonstrates good repeatability, long-term stability, and superior selectivity, providing a new approach for the design and fabrication of high-performance MEMS H₂ sensors.