A new strategy to one-step construct polyoxometalate/semiconductor one-dimensional tandem heterojunctions toward optimized conductometric sensing performances of ethanol gas

Gas sensing performances of homogenous semiconductors materials are limited by their high carriers recombination rate. Polyoxometalates (POMs), as a kind of electron acceptors, comes into sight in gas sensing field. In this study, three series of SnO2 @POMs@WO3 layered core-middle-shell nanofibers with tandem heterojunctions are first prepared utilizing one-step coaxial electrospinning. The tandem heterojunctions are continuously distributed in a one-dimensional line along the nanofibers. For the first time the gas sensing performances of one-dimensional tandem heterojunctions are investigated. Furthermore, the effects of different contents and types of POMs on gas sensing performance are studied. The response of POMs-modified nanofibers can be significantly improved compared to SnO2 @WO3 nanofibers. The optimized response to 100 ppm ethanol can reach 8.8. The enhancement can be attributed to that the addition of POMs electron acceptor, the construction of POMs/semiconductor tandem heterojunctions and the one-dimensional nano-structure can together promote the separation of carriers, which could remarkably improve gas sensing performances. These results provide a new strategy for developing high-performance gas sensors by synthesizing one-dimensional tandem heterojunctions as well as introducing POMs.