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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]

Porous double-channel α-Fe 2 O 3 /SnO 2 heterostructures with tunable surface/interface transport mechanism have been originally fabricated by the electrospinning and subsequent calcination process. With the increase of Sn content from 0 to 5 mol%, the morphology of α-Fe 2 O 3 -based materials changed from porous fibers to ribbons with both sides curled inward. Double-channel structure can provide more active sites and enhanced adsorption capacity with the large specific surface areas of 233.2 m2/g. The optimal α-Fe 2 O 3 /SnO 2 composites exhibit the highest response value (32.38) and fastest response/recovery times (33/58 s) than those of other samples to 100 ppm N,N-dimethylformamide (DMF) at 360 °C. Meanwhile, good cycling and long-term stability and high gas selectivity of the composites are conductive to the feasible detection to DMF under high temperature (≥360 °C) condition. The enhanced gas-sensitive properties of α-Fe 2 O 3 /SnO 2 composites at high temperature are closely related to phase composition, unique morphology, efficient n-n heterojunction and accelerated surface/interface charge transfer process. Significantly, the porous double-channel α-Fe 2 O 3 /SnO 2 composite is expected to be a potential candidate for DMF vapor detection in the dye or pesticide industry to prevent DMF explosion under high temperature conditions in the future. [Display omitted] • Porous double-channel α-Fe 2 O 3 /SnO 2 heterostructures is gained by electrospinning. • The special structure can provide more active sites and enhanced adsorption capacity. • Superior gas-sensing properties to DMF are obtained at high temperature (≥360 °C). • Fe/Sn-0.03 shows the highest response (32.38) and low detection limit (1 ppm) to DMF. • Sensing behavior depends on surface/interface multiple electronic transport routes. [ABSTRACT FROM AUTHOR]