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A one-step single-spinneret electrospinning method is used to prepare tunable In2O3 hierarchical structures of one-dimensional electrospun fibers with in situ growth of octahedron-like particles, a...

One-step single-spinneret electrospinning synthesis of 1D fibrous hierarchical structure can not only prevent the agglomeration or restacking of fibers or particles and enlarge surface active area but also promote the directional migration of electrons in materials and achieve effective regulation of resistances. Herein, tunable SnO2 and SnO2/ZnO fibrous hierarchical structures with in situ growth of monodisperse spherical-like particles on surface provide a new sight for adjusting component distribution, surface absorption and chemical reaction, electronic transmission path, and electron transfer efficiency. Compared with SnO2 porous fibers and SnO2 hierarchical structures, the optimal SnO2/ZnO sensors exhibit superior gas-sensing response value of 366-100 ppm ethanol at 260 °C as well as excellent gas selectivity and long-term stability, in which the enhanced gas-sensing mechanism is primarily derived from multilevel effective heterojunctions with unique interface electronic effects. Especially, these SnO2-based sensors can achieve favorable linear relationship of the response and gas concentration for sensitive trace detection in cosmetics for the first time, providing a new strategy to design composite materials for quantitative analysis of volatiles in the cosmetics evaluation process.

Hierarchical WO3/ZnWO4 1D fibrous heterostructures with tunable in-situ growth of WO3 nanoparticles on surface have been fabricated by the original one-step electrospinning technology combined with subsequent calcination process. Phase composition and morphology can be transformed from bead-like WO3 fibers to hierarchical WO3/ZnWO4 1D composites with the introduction of ZIF-8 into the precursor solution, which was mainly attributed to the combination of nucleation competition and crystal planes matching mechanisms during heat treatment. Compared with pure WO3 and WO3/ZnWO4-10%, WO3/ZnWO4-5% displayed the highest specific surface area value evaluated to be 268.57, indicating the prominent enhanced absorption behavior for targeted organic species. It is found that WO3/ZnWO4-5% composites have a response about 44.5 for 5 ppm HCHO, which was almost 8 times higher than that of sensor based on pure WO3 nanofibers at the optimal operating temperature. Meanwhile, the fast response/recovery time (12/14 s) and excellent stability characteristics (recycling, long-term, and humidity stability) towards HCHO can be also observed for WO3/ZnWO4-5% samples. The enhanced gas-sensing mechanism based on WO3/ZnWO4 composites can be ascribed to the synergistic effect of effective heterojunctions, large specific surface area, multiple reaction sites, and unique surface/interface electron transmission. The design and construction of hierarchical WO3/ZnWO4 1D materials attest to the significant potential of their use as novel gas sensors for detecting low concentration HCHO.

Morphology-tunable C–N/SnO2-based hierarchical microspheres with good gas sensitivity for triethylamine (TEA) have been fabricated via facile electrospinning and a subsequent calcination process. The reaction temperature and modifying calcining technology played a dominant role for the morphological evolution from precursor fibers to microspherical shapes and the formation of C–N-decorated SnO2 phase composition. C–N/SnO2/ZnO composites with tunable crystallinity, microstructure, and gas-sensing performance were strictly dependent on the added amount of Zn element. Fascinatingly, the constructed C–N/SnO2/ZnO/Au composites can not only precisely regulate the crystal size, dispersion status, loading position, and content of Au nanoparticles but also display excellent gas-sensing properties with ultrasensitivity and high selectivity under various temperature detections. The response of C–N/SnO2/ZnO/Au composites can reach up to approximately 1970, calculated to be 121.6 and 23.6 times for 50 ppm TEA molecule...

Tunable In2O3 hierarchical microstructures consisting of single crystalline octahedral particles and polycrystalline fibers have been synthesized by one-step electrospinning combined with a subsequent calcination process, in which their enhanced gas-sensing mechanism is mainly ascribed to the synergistic effect of two typical structural units.

Porous SnO2/NiO hollow nanofibers with effective surface transmission behavior have been prepared through a facile modified electrospinning method. The introduction of Ni component into the precursor solution can not only regulate the morphological evolution together with the nucleation and crystallization of oxide heterostructures at the elevated temperature action, but also significantly contribute to the enhancement of the gas-sensing performance for testing n-butanol gas. SnO2/NiO composites can present the highest response of 199 at the optimum operating temperature of 280 °C toward 100 ppm n-butanol gas, which is 4.5 times than that of pure SnO2 nanofibers. Meanwhile, the response/recovery times of the sensors can be immensely decreased from 57/16 s of pure sample to 36/10 s as the adding amount of Ni component increasing to 5%, along with the superior selectivity and long-term stability toward n-butanol. The excellent gas-sensing properties of the sensors can be mainly attributed to the flourishing porous one-dimensional (1D) microstructure containing the closely connected p-n heterojunctions of SnO2 and NiO, which can provide large specific surface areas with a mass of active sites to promote the reaction between n-butanol molecule and Oδ− on the surface.

ZIF-67-induced double-tubular 1D CeO2/Co3O4 heterostructures have been prepared by an electrospinning method with tunable morphological evolution mechanism. As the adding amount of ZIF-67 increasing, the morphologies of CeO2-based nanomaterials are changed from porous granular nanobelt to smooth curly shape, and finally formed a double-tubular structure. The optimal CeO2/Co3O4 products consisting of well-dispersed double-tubular nanostructure with the external diameter of about 200 nm display high specific surface area of 196.05 m2g−1 and superior photocatalytic performance of methylene blue (MB). The rapid degradation rate of 97% within 40 min and high cycling stability without significant decrease of photocatalytic activity could be attributed to the unique electron transfer synergetic mechanism based on the combination of double-tubular microstructure and CeO2/Co3O4 heterojunctions.

Composition-tunable C-N/SnO2/Co3O4 microspheres with available gas-sensing behavior were successfully fabricated via a facile electrospinning technology, mainly achieved by different adding amounts of ZIF-67. It is found that both the introduction of C-N components and the formation of p-n heterojunction can effectively accelerate electron transmission and enhance the gas sensitivity properties of the material toward trimethylamine (TEA). The highest response of C-N/SnO2/Co3O4 microspheres can reach up to approximately 154.3, calculated to be 9 times for 50 ppm triethylamine molecules at a temperature of 360 °C than that of C-N/SnO2 microspheres. Moreover, the threshold limit value of gas response can be observed as the exposure to even a concentration of merely 5 ppm TEA, indicating their potential application on detecting TEA released during the decay process of prawn in the low concentration region.