First principles investigation on selective hydrogen sensing properties of α-phase TeO2

alpha-phase TeO2 is a promising sensing material because of its unique ability to detect hydrogen gas. To investigate atomic-level mechanism on gas sensing of TeO2, the interaction between H-2, NH3, SO2, CO2, H2S, CH4 gases and TeO2 are studied via first principles simulations. By the calculated adsorption energy, radial distribution function, band gap and charge transfer, TeO2 shows a superior selective detection performance to hydrogen and it is consistent with experimental conclusion. The H-H bond of H-2 break after adsorption and a new H-O bond with length of 0.98 A forms between TeO2 and H-2. Moreover, the adsorption of H-2 causes an obvious increasing of DOS near the Fermi level, indicating a clear change in the electric conductivity. The calculated self-diffusion co-efficients show that the diffusion of hydrogen molecule in TeO2 is much easier than the other gases, suggesting a fast response of H-2 by TeO2. This work provides a theoretical foundation for analysis and design of TeO2-based hydrogen sensor. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.