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In this paper, the sensing property of Ni-BNNT to SO2, SOF2 and SO2F2 were investigated based on the DFT method to explore its potential as a chemical gas sensor. Our results show that Ni-doping could significant deform the electronic behavior of the BNNT, reducing its bandgap largely, from 3.712 eV to 0.601 eV. Ni-BNNT behaves strong chemisorption upon SO2 molecule with adsorption energy of -0.864 eV, while weak physisorption upon SOF2 and SO2F2 molecules with adsorption energy of -0.522 and -0.223 eV. The DOS analysis suggests the strong electron hybridization in SO2 system, while weak orbital interaction in the SOF2 and SO2F2 systems. Upon SO2, the Ni-BNNT could be a promising sensors for sensitive detection while it is unsuitable for detecting SOF2 or SO2F2 due to the weak interaction and extremely short recovery time. This work provides a first insight into the application of Ni-BNNT for detecting SF6 decomposed components, which would be beneficial for effectively evaluating the operation status of SF6 insulated devices.

We carried out a density functional theory study to investigate the adsorption behavior of four kinds of SF 6 decomposed products over the ZnO(101̅0) surface. The effects of O and Zn vacancies on the surface were also considered. For perfect ZnO(101̅0) surface, the adsorption of SO 2 and H 2 S exhibits stronger chemical interactions compared to the adsorption of SOF 2 and SO 2 F 2 . For SO 2 and H 2 S adsorption, there may exist new chemical bond formation between the molecule and the surface and the H 2 S molecule experiences one H–S broken bond. The introduction of O vacancy cannot obviously enhance the chemical interactions between these four molecules and the surface. However, the Zn vacancy on the surface can significantly elevate the chemical interactions between SO 2 /H 2 S and the surface. The two-coordinated O atom (O 2c ) on the surface plays an important role. For SO 2 and H 2 S adsorption, the S atom in SO 2 or H 2 S tends to bond to the O 2c atom, bringing much larger adsorption energy compared to the adsorption over the perfect ZnO(101̅0) surface. This work can provide a basis for surface modification of ZnO in applications to detecting SF 6 decomposed products by theoretical evaluation.

A high-performance sensor for detecting SF 6 decomposition components (H 2 S and SOF 2 ) was fabricated via hydrothermal method using Au nanoparticles/tin oxide/reduced graphene oxide (AuNPs-SnO 2 -reduced graphene oxide [rGO]) hybrid nanomaterials. The sensor has gas-sensing properties that responded and recovered rapidly at a relatively low operating temperature. The structure and micromorphology of the prepared materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, energy-dispersive spectroscopy (EDS), and Brunauer-Emmett-Teller (BET). The gas-sensing properties of AuNPs-SnO 2 -rGO hybrid materials were studied by exposure to target gases. Results showed that AuNPs-SnO 2 -rGO sensors had desirable response/recovery time. Compared with pure rGO (210/452 s, 396/748 s) and SnO 2 /rGO (308/448 s, 302/467 s), the response/recovery time ratios of AuNPs-SnO 2 -rGO sensors for 50 ppm H 2 S and 50 ppm SOF 2 at 110°C were 26/35 s and 41/68 s, respectively. Furthermore, the two direction-resistance changes of the AuNPs-SnO 2 -rGO sensor when exposed to H 2 S and SOF 2 gas made this sensor a suitable candidate for selective detection of SF 6 decomposition components. The enhanced sensing performance can be attributed to the heterojunctions with the highly conductive graphene, SnO 2 films and Au nanoparticles.