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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] • Low temperature TEA-sensing SnS 2 /MnS microflowers are originally fabricated. • DFT simulation shows the transformation from semiconductive to metallic nature. • SnS 2 /MnS-3 % exhibits high responses of 17.85/23.67 to 100 ppm TEA at 30/40 ℃. • The enhanced metallicity plays a vital role of the enhanced gas-sensing behavior. • New strategy for gaining effective sulfide RT gas-sensing materials is presented. The development of low-temperature SnS 2 -based sensitive elements with unique surface adsorption and transport regulation for triethylamine (TEA) has always been an intractable challenge. In the present work, ultrathin SnS 2 /MnS microflowers with enhanced metallicity have been prepared by a facile one-step hydrothermal method, which is especially beneficial for achieving superior TEA-sensing performance under room temperature (RT) condition. Compared with pure SnS 2 , the SnS 2 /MnS-3 % can obviously exhibit higher responses of 17.85 and 23.67, faster response/recovery times of 165/506 and 156/344 s, and the enhanced gas selectivity and stability to 100 ppm TEA at 30 and 40 ℃, respectively. Taking account of density functional theory (DFT) calculation, the transformation of SnS 2 -based sensors from semiconductive to metallic nature plays a critical role of the enhanced gas-sensing behavior with the increased gas molecules absorption and electron transport efficiency, which can provide a new strategy for constructing novel and effective sulfide RT gas-sensing composites. [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]

Currently, the construction of three-dimensional (3D) flower-like SnS 2 /In 2 S 3 heterostructures has been primarily developed for low-temperature gas-sensing detection of triethylamine (TEA) by a facile hydrothermal treatment. The thickness of nanosheets and the number of folds of self-assembled products can be well regulated as the introduction of In component increasing, as well as the distribution of effective SnS 2 –In 2 S 3 heterojunctions. All the as-prepared SnS 2 -based sensors can exhibit good gas sensitive response behavior to TEA at various low operating temperatures, even for the first time at room temperature. For example, the optimal SnS 2 -1% In have the highest response (21.01), the relatively fast response/recovery times, and superior gas selectivity and stability to 100 ppm TEA at 40 °C, compared with other samples. Besides the combination of the formation of SnS 2 –In 2 S 3 heterojunctions, abundant active sites of the self-assembled structures, and unique surface/interface transmission mechanism is beneficial to the enhanced gas-sensing performance, significantly, the generation of state density resonance effect can be employed for improving the electron transport efficiency due to the adjustment of state density near the Femi level. The available long-term, cycling, and humidity stabilities and the linear response relationship of the sensors greatly contribute for the potential application of seafood storage evaluation. • Flower-like SnS 2 /In 2 S 3 self-assembly with effective heterojunctions is obtained. • SnS 2 -based sensors can exhibit superior TEA-sensing behavior at low temperatures. • Available state density resonance effect plays the key role of sensing behavior. • SnS 2 /In 2 S 3 sensors can be used for the application of seafood storage evaluation. • Construction of new TEA sensors with state density resonance effect is provided. [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]