Gas sensing activity and mechanism of Aurivillius-type Bi2MoO6 nanosheets with different crystal facets

Crystal facets engineering emerges as a potent strategy for modulating the surface properties and gas sensing performance of semiconductor metal oxides. However, related studies have primarily focused on conventional binary metal oxides gas sensing materials, while few studies have investigated the crystal facets-dependent gas sensing activity of recently developed ternary metal oxides. Herein, the effect of crystal facets on the gas sensing activity of Aurivillius-type layered perovskite structure material Bi 2 MoO 6 was studied. It was shown that Bi 2 MoO 6 nanosheets with {001} crystal facets exhibited significantly enhanced gas sensing activity with a high response value of 72 (R a /R g ) towards 100 ppm of triethylamine at relatively low working temperature of 250 °C, which was about 10 times higher than that of Bi 2 MoO 6 nanosheets with {010} crystal facets. The gas mechanism was elucidated at the atomic and electronic levels through first principles calculation combined with experimental characterization. On the one hand, the synergistic effect of Mo/Bi bimetallic sites makes the adsorption/charge transfer between {001} facets and triethylamine much stronger. On the other hand, {001} facets have abundant chemically adsorbed oxygen and oxygen vacancy on the surface, which act as the active species in gas sensing. These results not only significantly broaden the application scope of Aurivillius-type layered perovskite structure materials in the realm of gas sensing, but also provide important guidance for the study of gas sensing mechanism in ternary metal oxides.