Search

[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]

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]

[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]