Hongnan Zhang

Highly Sensitive and Stable Humidity Nanosensors Based on LiCl Doped TiO2 Electrospun Nanofibers

A new type of humidity nanosensor based on LiCl-doped TiO2 nanofibers with poly(vinyl pyrrolidone) (PVP) nanofibers as sacrificial template has been fabricated through electrospinning and calcination. The sensor exhibited excellent sensing characteristics, such as ultrafast response and recovery times, good reproducibility, linearity, and environmental stability, which are of importance for applications in humidity monitoring and control.

Adsorption of Cu(II) from aqueous solution by anatase mesoporous TiO2 nanofibers prepared via electrospinning

Anatase mesoporous titanium nanofibers (m-TiO(2) NFs) have been synthesized from calcination of the as-spun TiO(2)/polyvinyl pyrrolidone (PVP)/pluronic123 (P123) composite nanofibers at 450 °C in air for 3h. The structures and the physicochemical properties of m-TiO(2) NFs are characterized by scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherm analysis, and determination point of zero charge, respectively. An investigation of Cu(II) adsorption onto m-TiO(2) NFs has been studied in this research. The pH effect, adsorption kinetics, and adsorption isotherms are examined in batch experiments. Experimental data were analyzed using pseudo-first order and pseudo-second order kinetic models. It was found that adsorption kinetics were the best fitting by a pseudo-second order kinetic model. The optimum pH for Cu(II) adsorption was found to be 6.0. The equilibrium data were analyzed by the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models, which revealed that the Freundlich isotherm is the best-fit isotherm for the adsorption of Cu(II). Compared to the TiO(2) NFs (regular anatase titanium nanofibers) in the same experimental conditions to elucidate the role of the mesoporous structure of m-TiO(2) NFs, experimental results showed that the m-TiO(2) NFs had a better adsorption capacity for Cu(II) due to its higher surface area.

Assembly of Pt nanoparticles on electrospun In2O3 nanofibers for H2S detection

In this paper, we presented a simple and effective solution route to deposit Pt nanoparticles on electrospun In2O3 nanofibers for H2S gas detection. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed that large quantities of In2O3 nanofibers with diameters about from 60 to 100 nm were obtained and the surface of them was decorated with Pt nanoparticles (5-10 nm in size). The In2O3 nanofibers decorated by Pt nanoparticles exhibited excellent gas sensing properties to H2S, such as high sensitivity, good selectivity and fast response at relatively low temperature.

Au‐Doped Polyacrylonitrile–Polyaniline Core–Shell Electrospun Nanofibers Having High Field‐Effect Mobilities

Au-doped polyacrylonitrile–polyaniline core–shell nanofibers are fabricated via electrospinning and subsequent gas-phase polymerization, providing a very high field-effect mobility of up to 11.6 cm2 V−1 s−1. This method is also suitable for other conducting polymers and may eventually lead to a new and simplified fabrication of high-performance polymer organic field-effect transistors.

Mg2+/Na+-doped rutile TiO2 nanofiber mats for high-speed and anti-fogged humidity sensors

Mg(2+) and Na(+) doped rutile TiO2 nanofibers have been prepared through in situ electrospinning technique and calcination with poly(vinyl pyrrolidone) (PVP) nanofibers as sacrificed template. The as-prepared composite nanofibers are spin-coated onto a ceramic substrate with three pairs of carbon interdigital electrodes to measure its humidity sensing behaviors. The product exhibits high-speed response (2s) and recovery (1s) for detecting moisture. Additionally, under UV irradiation, a water contact angle (theta) of nearly 0 degrees has been observed based on the product, providing our humidity sensor with the anti-fogged properties.

One‐Dimensional Polyelectrolyte/Polymeric Semiconductor Core/Shell Structure: Sulfonated Poly(arylene ether ketone)/Polyaniline Nanofibers for Organic Field‐Effect Transistors

A polyelectrolyte/polymeric semiconductor core/shell structure is developed for organic field-effect transistors (OFETs) based on sulfonated poly(arylene ether ketone)/polyaniline core/shell nanofibers via electrospinning and solution-phase selective polymerization. The polyelectrolyte does not work as a gate dielectric, but can provide an internal modulation from the nanointerface of the 1D core/shell nanostructure. The transistor devices display very high mobilities.

Conductivity study of ABO3-type nanostructured materials

Abstract The relation of conductivity to temperature, composition and compaction pressure was studied for a series of nanostructured composite oxides, LaFeO3, LaCoO3, and La1−xSrxFe1−yCoyO3. The results show that although the conductivity of nanostructured materials is lower, the slope of the conductivity-temperature curve is higher compared with large grain materials. Moreover, their conductivity changes with composition, compaction pressure and atmospheric pressure.

One-dimensional isomeric and hierarchical TiO2 nanostructures: novel air stable semiconducting building blocks

One-dimensional (1D) semiconducting nanostructures, as both interconnections and functional units in fabricating electronic, biological/chemical sensors, optoelectronic, electrochemical, and electromechanical devices, attract immense interest. However, all those 1D semiconducting nanostructures are sensitive to both volatile organic compounds (VOFs) and relative humidity (RH), causing the instability of those devices operated in air (except in biological/chemical sensors). Herein, we demonstrated an effective route to not only stabilize 1D semiconducting nanostructures in air but also maintain their electrical properties by constructing 1D isomeric semiconducting nanorods on 1D semiconducting nanostructures to form 1D isomeric and hierarchical semiconducting nanostructures. 1D isomeric and hierarchical TiO2 nanostructures (IHTNs) were chosen as a model, both excellent air stability and good electrical properties can be achieved. With such IHTNs as building blocks, a stable field-effect transistor has been realized.

EFFECT OF THE THICKNESS OF PAN/Au MODIFIED ELECTRODE ON BIOSENSOR SENSITIVITY

A simple electrospinning method was used to control the thickness of polyacrylonitrile (PAN)/Au modified electrode. The influence of membrane thickness to modified electrode sensitivity was discussed. In our experiment, a 20-min electrospinning time and a mass ratio of 3:1 PAN/HAuCl4 are the optimum parameters to generate the high performance PAN/Au membrane modified electrode for detecting H2O2 which has a sensitivity of 145.63 mA M-1 cm-2) and a wide linear range of 20 μM–20 mM.