MEMS sensor based on MOF-derived WO3-C/In2O3 heterostructures for hydrogen detection

Rational structure design of sensing materials is the most effective way to obtain a hydrogen (H2) sensor with optimal performance. Herein, a porous heterostructure WO3-C/In2O3 was designed and prepared by in-situ coupling carbon layer and WO3 into MOF-derived (metal organic framework) In2O3. In combination with Micro-Electro-Mechanical System (MEMS), a miniature H2 sensor using WO3-C/In2O3 as the active sensing material was fabricated. Compared with the bare In2O3 sensor, the sensor based on WCI-9 (the mass ratio of WO3 to In2O3 in WO3-C/In2O3 is 9 wt%) shows higher response value and lower operating temperature (Ra/Rg =10.11 @ 1000 ppm; 250 oC). Moreover, the WCI-9 sensor possesses a fast response-recovery speed (1.9/9.2 s @ 200 ppm) and a low limit of detection (LOD) (5 ppm) for H2. The good performance of the WCI-9 sensor is attributed to the hierarchical porous structure and multicomponent heterojunctions present in the material. This work not only provides an effective method for H2 detection, but also a strategy for constructing sensing materials with multicomponent heterojunctions.