ИСТИНА

Semiconductor gas sensors are widely used to control the concentration of toxic substances in the air. N-type oxides SnO2, ZnO, In2O3 are typical sensitive materials, but their use in humid air is limited because of the strong decrease in the signal value. The negative influence of water can be reduced by making p-n structure or doping by different metals. This work is devoted to the investigation of nanofibres based on cobalt modified ZnO, obtained by electrospinning. The method makes it possible to obtain multicomponent nanofibres with different distribution of components: homogeneous solid solutions, fibers with an island distribution of the second component over the surface of the main phase filament, and core-shell structures. The samples were characterized by XRD, BET, SEM, HAADF-STEM, and STEM-EDX mapping. The modification with low cobalt concentration (5 at. %) results in formation of hollow tubes of ZnO-based solid solution whose resistance is 1000 times higher than the corresponding value for bare ZnO nanofibres. The increase in cobalt content leads to the appearance of second phase of zinc cobaltite with different [Co]/[Zn] ratio. The sensor properties of nanofibers to NO, NO2, NH3, CO and H2S were studied under different air humidity conditions at the temperature 80-250C. Nanofibres based on cobalt modified ZnO demonstrates high sensor signal toward H2S which is retained with increasing air humidity up to RH = 60%.