Lijie Wang

Improved and excellent humidity sensitivities based on KCl-doped TiO2 electrospun nanofibers

Pure and KCl-doped TiO2 nanofibers have been synthesized by electrospinning and calcination technique. The measurement results by the sensors fabricated from these fibers at the working electrodes show that KCl-doped TiO2 nanofibers hold the improved humidity sensing properties with the resistance varying more than four orders of magnitude in the range of 11%–95% relative humidity, while the resistance of pure TiO2 nanofibers changes only about two orders of magnitude. An ion-controlled model has been established to explain the results further. Additionally, excellent sensing characteristics (rapid response and recovery behavior and good stability) have been also found based on KCl-doped TiO2 nanofibers, which endows our product with the potentials for humidity sensors.

Synthesis of core–shell α-Fe2O3@NiO nanofibers with hollow structures and their enhanced HCHO sensing properties

Different components and well-defined structures may cooperatively improve the performances of composite materials and enhance their applicability. In this paper, core–shell α-Fe2O3@NiO nanofibers (α-Fe2O3@NiO CSNFs) with hollow nanostructures are synthesized by a facile coaxial electrospinning method and calcination procedure. Considering the temperature-dependent solute degradation process and different influencing factors including the solvent evaporation rate and phase separation, a multistage formation mechanism has been proposed to understand the formation of the CSNF structure. The gas sensing tests indicate that the α-Fe2O3@NiO CSNFs exhibit significantly improved gas sensitivity and selectivity performances in comparison with NiO hollow nanofibers (NiO HNFs) and α-Fe2O3 nanofibers (α-Fe2O3 NFs). The response of α-Fe2O3@NiO CSNFs to 50 ppm HCHO at 240 °C is ∼12.8, which is 10- and 7.1-times higher than those of pure NiO and α-Fe2O3, respectively. The synergy between the heterojunction, core–shell hollow nanofiber structure and Fe loading into the NiO shell contribute to the enhanced response of α-Fe2O3@NiO CSNFs. Moreover, extremely fast response–recovery behavior (∼2 s and ∼9 s) has been observed at the optimal working temperature of 240 °C. The detection limit for HCHO could be lower than 1 ppm. These favorable gas sensing performances make the α-Fe2O3@NiO CSNFs promising materials for gas sensors.

Core–shell Co3O4/α-Fe2O3 heterostructure nanofibers with enhanced gas sensing properties

1D Co3O4/α-Fe2O3 core–shell nanofibers were successfully fabricated by a facile and template-free coaxial electrospinning method, and developed for acetone gas detection. Morphology and component characterizations confirm that the as-prepared 1D heterostructures possess a well-defined core–shell structure with Co3O4 in the core and α-Fe2O3 in the shell. The unique 1D core–shell nanostructures, heterojunction effect at the Co3O4/α-Fe2O3 interfaces and the catalysis of Co3O4 endow the Co3O4/α-Fe2O3 core–shell nanofiber-based sensor with an enhanced gas sensing performance in terms of good sensing selectivity, high sensitivity (11.7), rapid response/recovery times (2 s/20 s) and better reproducibility for acetone gas. The gas sensing mechanism is proposed in detail. Overall, the 1D Co3O4/α-Fe2O3 core–shell heterostructure nanofibers synthesized through coaxial electrospinning make a promising and effective acetone sensor.

Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core–shell nanofibers with high-performance semiconducting properties

FETs based on Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core-shell nanofibers have been fabricated and exhibit high mobility (∼2.0 cm(2) V(-1) s(-1)).