Lianyuan Wang

The fabrication of In2O3 nanowire and nanotube by single nozzle electrospinning and their gas sensing property

It has been reported a lot that nanowire and nanotube semiconductor oxide type sensor possess excellent sensing property. Many works ascribed excellent sensing properties to the big specific surface area. Herein, In2O3 nanofiber and nanotube were synthesized by single nozzle electrospinning and followed by calcination with different heating rate. And the samples were characterized by scanning electron microscopy, and powder X-ray diffraction. Their gas sensing properties were studied to investigate the advantages of their morphologies, and the response and recovery dynamic curves were also tested to investigate their gas sensitive characteristics. The results show that acetone sensing sensitivity based on nanotubes is better than that of nanowires.

Synthesis and acetone gas sensing properties of α -Fe 2 O 3 nanotubes

Abstractα-Fe2O3 nanotubes was successfully prepared by single nozzle electrospinning method. Scanning electron microscope (SEM) was used to characterize the morphology of α-Fe2O3 nanotubes. The gas sensing properties of α-Fe2O3 nanotubes were investigated in detail. The results exhibit relatively good sensing properties to acetone at 240 °C. The response and recovery times are about 3 and 5 s, respectively. The structure of nanotubes is beneficial to the gas sensing properties, which will enlarge the surface-to-volume ratio of α-Fe2O3 and then be available for the transfer of gas, and thus improved the sensor performance consequentially.

Induced growth of high quality ZnO thin films by crystallized amorphous ZnO

This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80°C. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.

Novel ruptured Sm2O3–In2O3 porous nanotubes with excellent formaldehyde sensing properties

Ruptured Sm2O3–In2O3 nanotubes with pores on surface have been successfully synthesized via a single-capillary electrospinning process. The cracks and pores distributed on the nanotube surfaces which can be seen in SEM images facilitate gas transport in materials and increase effective contact areas between gas molecules and materials. Gas sensors based on Sm2O3–In2O3 have been fabricated and investigated for formaldehyde detection. The response to 100ppm formaldehyde at the optimum operating temperature of 240∘C is 66.82.

Preparation, characterization, and optical properties of carbon doped ZnO nanocrystal

In this paper, we prepared carbon doped nanocrystalline ZnO by pyrolyzed zinc stearate at 250°C and 300°C respectively. The XRD curves indicate the sample has polycrystalline hexagonal wurtzite structure. The XRD data of the sample prepared at 250°C and 300°C has a bigger angle shift about 0.05°and 0.3°respectively. That indicate the structure of the sample has some changes. The EDS indicate the sample contains Zn, O and C. So the XRD shift may attribute to the C. The XPS indicate the C doped in the crystal lattice of ZnO of the sample prepared at 300°C, and the sample prepared at 250°C may be only a few of C doped in the crystal lattice of ZnO. The PL of the sample prepared at 300°C only has a weak ultraviolet emission, which indicates C modified the nanocrystalline ZnO surface as a non-radiative recombination center. In this process C could non-radiatively recombine the carries on the nanocrystallin ZnO surface. The sample prepared at 250°C has a strong visible emission at about 530 nm. This emission band could be attributed to oxygen vacancy because C schlepped some oxygen on the nanocrystalline ZnO surface.

Photoluminescence Study of the Interface of Nanocrystalline ZnO/Amorphous ZnO

We studied the growth process of nanocrystalline ZnO which grown in amorphous ZnO by photoluminescence (PL). In this process, we found a new visible emission band, the visible emission intensity increased quickly at first, then decreased exponentially, while the peaks energy has a red shift from 583nm to 615nm along with the increasing reaction temperature. The results indicate this visible emission band correlate with the nanocrystalline ZnO/amorphous ZnO interface. The interface was polarized by the activated amorphous ZnO acts with the nanocrystalline ZnO surface, thus charge carrier was self-trapped on the nanocrystalline ZnO surface and emitted visible PL by recombination. We studied the changes rule of the nanocrystalline ZnO / amorphous ZnO interface by the characteristic of visible emission.

Enhanced ultraviolet emission of ZnO/amorphous ZnO core-shell structure

The ZnO quantum dots prepared via the solid-state pyrolytic reaction were studied. Our studies revealed the surface of ZnO quantum dots modified by amorphous ZnO. The as prepared quantum dots with sizes varying from 2-3 nm yields a blue shift about 0.15eV and shows an enhanced ultraviolet emission of 3-5 times over that of high quality ZnO nanoparticles.