Ultra-Low Detection Limit MEMS Hydrogen Sensor Based on SnO2 Nanospheres with Lots of Defects

Abstract

In this paper, SnO2 nanospheres with a lot of defects (SnO2-D) were synthesized simply by annealing SnO2 at the different temperature (300 °C, 400 °C and 500 °C) in the hydrogen (H2) atmosphere. There are many oxygen vacancies in SnO2 due to reaction between H2 and oxygen when the SnO2 was exposed in H2 atmosphere. The X-ray photoelectron spectroscopy (XPS) and Electron paramagnetic resonance (EPR) analysis showed that there are abundant oxygen vacancies on the surface of the SnO2-D4 (with the optimal annealing temperature of SnO2 is 400 °C). The gas sensitivity test results show that sensor based on SnO2-D4 showed an ultra-sensitive H2 detection ability down to 1 ppm. Moreover, the response of the sensor fabricated with SnO2-D4 to 10 ppm H2 at the optimal operating temperature of 250 °C is as high as 2.7, which is about 2 times higher than that of the SnO2 sensor. The improved gas sensing properties can be attributed to generation of oxygen vacancies in the SnO2-D4. Our present results demonstrate that SnO2 with abundant oxygen vacancies can significantly to detect the ultra-low concentration H2 and the method of manufacturing oxygen vacancies defects has great potential in improving the gas-sensing performance of metal oxide semiconductor. Figure 1