One-step fabrication of TiO2@polyoxometalates@α-Fe2O3 one-dimensional tandem heterojunctions for conductometric acetone sensors

Herein, we provide a new strategy to construct TiO2 @[email protected] α-Fe2O3 one-dimensional tandem heterojunctions materials utilizing one-step coaxial electrospinning. Three series of TiO2 @[email protected] α-Fe2O3 core-middle-shell nanoribbons with different Keggin-type POMs are synthesized. The tandem heterogeneous interfaces between the three layers are continuously distributed in a one-dimensional line along the nanoribbons. Gas sensing performances of the nanoribbons are investigated. The gas sensors show significantly improved sensitivity and selectivity to acetone compared with both composite nanoribbons and POMs-free nanoribbons. The enhancement can be due to the addition of POMs electron acceptors, the construction of tandem heterojunctions and the one-dimensional nano-structure, which can together accelerate electrons transfer and reduce their recombination. Besides, the effects of different kinds and contents of POMs on gas sensing performance are studied. The results show that the response value of the optimal sensor to 100 ppm acetone can reach 14.81, which is 2.9 times of that of TiO2 @ α-Fe2O3 double-layered nanoribbons. This work provides a novel strategy for developing high performance gas sensors by constructing tandem heterojunctions as well as introducing POMs electron acceptor, and offers new insight into the development of POMs-based gas sensors.