Chemoresistive gas-sensing properties of highly dispersed Nb2O5 obtained by programmable precipitation

Nb2O5 powder obtained by programmable precipitation was used to form a thick gas-sensing film as part of a chemoresistive gas sensor, by screen-printing. The coating of orthorhombic Nb2O5 consisted of nano-particles with a size of 41.0 +/- 2.5 nm. XPS revealed Nb5+, Nb4+ and Nb2+ as well as oxygen vacancies in the crystal structure of niobium oxide. As a result of studying the chemoresistive gas-sensing properties of Nb2O5, it has been shown that among the analysed gases (H-2, CO, NH3, H2S and O-2), the greatest sensitivity was observed for oxygen and hydrogen sulphide. Nanocrystalline niobium oxide showed a high and reproducible response to 0.02-20% O-2 (S-1 = 1.1-19.0) at a very low detection temperature of 200 degrees C for oxygen sensors. At an operating detection temperature of 250 degrees C, a high and reproducible response to low concentrations of hydrogen sulphide of 4-100 ppm (S-2 = 1.2-6.6) was detected for Nb2O5. The influence of humidity on the received signals when detecting oxygen and hydrogen sulphide was studied in detail: there was a decrease in the resistance and the response value at 95% humidity in the medium of both gases. However, unlike the process of detecting H2S (when the response of S-2 was almost lost), when determining oxygen, the response of S-1 was reduced by a factor of two only, which suggests the possibility of determining the content of O-2 in high humidity conditions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The Nb2O5 powder obtained by programmable precipitation was used to form a thick gas-sensing film for a chemoresistive gas sensor, demonstrating high sensitivity to oxygen and hydrogen sulphide at low detection temperatures. The influence of humidity on the detection of oxygen and hydrogen sulphide was studied, showing a decrease in resistance and response value at high humidity levels, with different impacts on the two gases' detection signals.