Search

The detection of the identities and concentrations of sulfur hexafluoride, SF 6 , decomposition products is important for evaluating the conditions of SF 6 -gas-insulated equipment. This study is a preliminary test of the use of cassiterite (110) for detecting SF 6 and SF 6 decomposition gases, including HF, H 2 S, SO 2 , SOF 2 , SO 2 F 2 , CF 4 , CO, and CO 2 . First-principles calculations were adopted to investigate the adsorption mechanism of SF 6 decomposition gases on a cassiterite (110) surface, using adsorption energy, geometrical structure, frontier molecular orbitals, electron density, density of states, potential energy, and work functions. We found that the adsorption of H 2 S made a noticeable change in the electronic properties of the (110) surface. The adsorption of SO 2 strongly influenced the charge distribution of the cassiterite (110) surface and made the greatest decrease in the work function of the nine gas molecules tested. Conversely, changes in the cassiterite's electronic properties induced by other gases, especially SF 6 , were slight. Therefore, cassiterite could be a promising candidate for highly selective and sensitive sensors to detect H 2 S and SO 2 in SF 6 decomposition gases. [ABSTRACT FROM AUTHOR]

In order to take insight into the gas sensing performance of single ultrathin WO 3 nanowire, we performed first principles calculation to investigate the gas adsorption properties and used non-equilibrium Green function (NEGF) to investigate the electron transport properties of WO 3 nanowires with gas adsorption. Our investigation indicated that the WO 3 nanowires with/without oxygen vacancies are both sensitive to H 2 S due to the large adsorption energies and distinct charge transfer. Besides, we found that the WO 3 nanowire with O a type oxygen vacancies is highly selective to SO 2. We supposed that the high chemical activity and the small molecular volume of H 2 S and SO 2 are the main reasons of the selectivity. Finally, the negative differential resistance (NDR) effect of single ultrathin WO 3 nanowire and the gate voltage were proposed to benefit the application of WO 3 nanowires gas sensors. We also supposed two ways to take advantage of the NDR effect of single ultrathin WO 3 nanowire in gas sensing applications. It should be noted that this is the first theoretical investigation of WO 3 nanowires gas sensors considering the electron transport properties. Our work highlighted the possibility to use the single ultrathin WO 3 nanowire as superior gas sensors for SO 2 and H 2 S. Image 1 • The single ultrathin WO 3 nanowire without oxygen vacancies was sensitive to H 2 S. • The single ultrathin WO 3 nanowire with oxygen vacancies was sensitive to SO 2. • High chemical activity and small molecular volume are main reasons of selectivity. • Negative differential resistance effect will benefit gas sensing application. [ABSTRACT FROM AUTHOR]