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[Display omitted] • Bimetallic MOFs-derived hierarchical WO 3 /ZnWO 4 /CoWO 4 heterostructures are gained. • Morphology and sensing behavior of the samples are tuned by the amounts of ZIFs. • Good selectivity and stability of WO 3 -based composites can be observed at 25 °C. • Abundant polyoxometalate electron acceptors are distributed on the coarse surface. • Sensing mechanism is relied on the rapid transport of carriers and plentiful POMs. Bimetallic MOFs-derived hierarchical WO 3 /ZnWO 4 /CoWO 4 heterostructures were prepared by electrospinning for achieving superior n-butanol-sensing property at low operating temperatures. Porous chain-like structures can gradually transformed into porous mulberry-like structures composed of various accumulated particles as increasing the additive amount of Zn/Co-ZIFs. High selectivity and stability of WO 3 -based composites to 100 ppm n-butanol can be observed at 25 °C, including the large sensitivity of 32 and the fast response/recovery times of 115/179 s. The enhanced gas-sensing performance is primarily ascribed to the increased specific surface area, plentiful polyoxometalate, and effective heterojunctions, obviously promoting surface/interface absorption behavior and electron transport process. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ growth of porous WO 3 /FeWO 4 hierarchical structure is originally obtained. • The distribution of p-n heterojunctions is dependent on the content of MIL-101. • The optimal operating temperatures to n-butanol can be reduced from 220 to 25 °C. • Efficient heterojunction interfaces gain surface electronic structure modulation. • A strategy of novel room temperature n-butanol-sensing performance is presented. This study originally reports the in-situ construction of porous WO 3 /FeWO 4 ribbon-like hierarchical composites with unique and intense heterojunction interface behavior and the enhanced adsorption and carrier transport capability for effectively detecting n-butanol at room temperature. The introduction of different adding amounts of MIL-101 plays the key role of the morphological evolution of WO 3 -based microstructures with the well-distributed nanoparticles in situ growth on the surface by a facile electrospinning and subsequent calcination process. Compared with pristine WO 3 , a sharp and useful reduction of the optimal operating temperature from 220 to 25 °C can be observed as the Fe component increasing, mainly owing to the inverted p-type gas sensitive response caused by the controllable variable of FeWO 4 phase in the multiple effective WO 3 -FeWO 4 heterojunctions. The optimal WO 3 /FeWO 4 composites can display the highest response of 12.3 and a relatively short response/recovery times of 110/140 s to 100 ppm n-butanol at 25 °C, together with the superior gas selectivity, repeatability, humidity and long-term stability. Density functional theory (DFT) simulation is employed for verifying the significant adsorption interaction and charge transfer between n-butanol molecule and WO 3 /FeWO 4. Regular distribution of WO 3 -FeWO 4 heterojunction interfaces can not only determine the collaborative modulation of electronic structures, but also provide the efficient surface/interface transport mechanism for MIL-101 induced one-dimensional (1D) hierarchical ribbons. Actually, the integrated gas-sensitive components based on WO 3 /FeWO 4 composites exhibit the rapid response characteristic under room temperature condition and provide a friendly strategy of optimizing the practical detection of ppm-level n-butanol for other inorganic heterogeneous sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • An effective surface double oxygen defect strategy is gained for CeO 2 /WO 2.9 sensors. • Tunable button-shaped porous CeO 2 /WO 2.9 composites are initially fabricated. • CeO 2 /WO 2.9 sensors exhibit the excellent n -butanol detection at room temperature. • Gas-sensing mechanism deeply depends on surface double oxygen defect engineering. • New insight for constructing double oxygen defect induced gas sensors is provided. In the present work, a series of CeO 2 /WO 2.9 composites with a tunable structure and thickness are originally fabricated by innovating different additional quantities of H 2 WO 4 during the hydrothermal process. Optimal Ce/W-0.25 sensors have a higher response value of 23.68 to 100 ppm n -butanol at room temperature than that of pure CeO 2 (1.26) at 200 ℃. The unique surface double oxygen defect engineering between CeO 2 and WO 2.9 has a remarkable role in enhanced gas sensing, formation of the CeO 2 -WO 2.9 heterojunction, and effective surface/interface transport mechanism. The electron transfer between WO 2.9 and CeO 2 driven by oxygen defects on the surface of CeO 2 can easily facilitate the interconversion between Ce3+ and Ce4+. This work provides a new insight and the facile fabrication pathway for constructing double oxygen defects-derived CeO 2 -based heterostructures for developing novel n -butanol gas sensors with excellent sensing performance at room temperature. [ABSTRACT FROM AUTHOR]