Ultra-Low Detection Limit MEMS Hydrogen Sulfide Sensor Based on Tungsten Oxide Nanorods with Lots of Oxygen Vacancies

In this paper, tungsten oxide nanorods were successfully synthesized by using ordered mesoporous silica of SBA-15 as a template and 12-phosphotungstic acid as a precursor of tungsten oxide under a hydrogen (H2) atmosphere. XRD and HRTEM characterization show that the composition of tungsten oxide synthesized is WO2.83. The gas sensing test results show that WO2.83 can detect 5 ppb H2S. Moreover, the response of the sensor fabricated with WO2.83 to 200 ppb H2S at the optimal operating temperature of 280 °C is as high as 1.8, which is increased by nearly 50% than that of the common WO3 without redundant oxygen vacancies. The improved gas sensing properties can be attributed to rich oxygen vacancies in the WO2.83. Our present results also demonstrate that WO2.83 with a lot of oxygen vacancies can significantly enhance the gas response to ultra-low concentration H2S, and this method of manufacturing defects has great potential in improving the gas-sensing performance of metal oxide semiconductor. Figure 1