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Porous MoO3/V0.13Mo0.87O2.935 heterostructures self-assembled with 2D nanosheets have been primarily prepared by a facile method for effectively detecting ethanol at room temperature. The V0.13Mo0.87O2.935 phase contributes to modified microspheres and improved surface/interface structures. The enhanced sensing mechanism benefits from the effects of MoO3–V0.13Mo0.87O2.935 heterojunctions and tunable microstructure.

In this paper, we focused on the hydrothermal synthesis of ZnO structures with varied morphologies by finely adjusting the ratio of water to glycol, indicating the polarity of the solution affects the growth habit of the crystal. It showed that the precise control in growth rates of different ZnO crystal faces in mixed solution is the key factor to control the morphologies of ZnO samples. Compared to pure ZnO, the response value of the hemispherical ZnO/Au to 100 ppm triethylamine (TEA) has been improved to 104.8 at the operating temperature of 260 °C, and the response and recovery time are 5 and 2 s, respectively. The enhancing mechanism of as-prepared ZnO/Au hemispheres can be ascribed to the combination of the tuning of surface electron transfer , microstructures, and the electronic and chemical sensitization of Au nanoparticles , along with the formation of Schottky junction between Au nanoparticles and ZnO hemispheres. The excellent sensing performance of ZnO/Au composite hemispheres enables them to function as promising materials for actual application in the monitoring and detecting of TEA.

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.

C-N/Co/Ti composites derived from ZIF-67@TiO2 precursors have been fabricated by a facile thermal treatment process. The morphology and composition are highly dependent on the available parameters inferring of exact hydrolysis of tetrabutyl titanate and sintering temperature. The obtained hierarchical microstructure is composed of numerous dodecahedron-like hollow boxes decorated with in-situ growth of size-tunable and twisting nanotubes on surfaces. The effective elemental separation of Ti and Co on the upper and lower ends of nanotubes can be realized by regulating the ionic migration and crystalline phase formation process at a high temperature. The as-prepared C-N/Co/Ti composites exhibit the enhanced electrocatalytic activities to oxygen reduction reaction (ORR) via a favorable four-electron pathway and the desired reaction kinetics with the low Tafel slope (67.8 mV dec−1), as well as the excellent methanol tolerance in comparison with the Pt/C electrocatalysts. The superior ORR electrocatalytic performance would be mainly contributed to the combination of the designed multi-phase composition, the enhanced surface adsorption/desorption, the modified surface/interface electron transfer mechanism, and the constructed Co/Ti double-active sites on different locations of microstructure. The present work presents a new insight for the synthesis of C-N-based inorganic composite with outstanding electrocatalytic behavior for ORR process.