Effective monitoring and classification of hydrogen and ammonia gases with a bilayer Pt/SnO_2 thin film sensor

摘要

The monitoring and classification of different gases, such as H-2 and NH3 using a low-cost resistive semiconductor sensor is preferred in practical applications in hydrogen energy, breath analysis, air pollution monitoring, industrial control, and etc. Herein, porous bi-layer Pt/SnO2 thin film sensors were fabricated to enhance H-2 and NH3 sensing performance for effective monitoring and classification. Different Pt film thicknesses of 2, 5, 10, and 20 nm were deposited on 150 nm SnO2 film-based sensors by sputtering method to optimize the response to H-2 and NH3 gases. Gas sensing results showed that the fabricated Pt/SnO2 films significantly improved the sensor response to NH3 and H-2 compared to pure SnO2 thin film. The sensors based on 5 and 10 nm Pt catalyst layers presented the highest responses to H-2 and NH3, respectively. The optimal working temperature for NH3 was in the range from 250 degrees C to 350 degrees C, and that for H-2 gas is less than 200 degrees C. The response of Pt/SnO2 sensors to CH4, CO, H2S, and liquefied petroleum gas was much lower than that to NH3 and H-2 supporting the high selectivity. On the basis of sensing results at different working temperatures or Pt thicknesses, we applied a radar plot and linear discriminant analysis methods to distinguish NH3 and H-2. The results showed that H-2 and NH3 could be classified without any confusion with different Pt layer thicknesses at a working temperature of 250 degrees C. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.