Lacunary polyoxometalates-induced controllable synthesis of Fe2O3/Si-FeWO4 heterostructure nanotubes for selective sensing of m-xylene

Abstract

Metal oxide-based gas sensors encounter challenges in effectively detecting hazardous benzenes due to their stability and structural similarities. Here we report an innovative in situ growth method for synthesizing Fe2O3/Si-FeWO4 heterostructure nanotubes (NTs) using highly negatively charged multivacant lacunary TBA4H6[SiW9O34]·2H2O (α-SiW9) and Fe3+ as precursors. A two-step process involving electrospinning followed by a thermal oxidation method was employed to synthesize a series of the uniform Si-FeWO4 decorated Fe2O3 heterostructure NTs. Considering the rich Fe2O3/Si-FeWO4 active interfaces, rapid electron transfer, and high specific surface area, the optimal Fe2O3/Si-FeWO4 based sensors demonstrate significantly higher sensitivity (S = 27.5) towards 50 ppm m-xylene in comparison to pristine Fe2O3 (S = 1.8). Furthermore, the Fe2O3/Si-FeWO4 exhibits excellent stability, humidity resistance, and high selectivity for m-xylene. This work offers an efficient, cost-effective strategy to synthesize Fe2O3/Si-FeWO4 heterostructure NTs, with prospects for synthesizing other advanced sensing heterostructure nanomaterials with lacunary polyoxometalates as precursors.