Tiekun Jia

Synthesis, Characterization, and Photocatalytic Activity of Zn-Doped SnO2/Zn2SnO4 Coupled Nanocomposites

Zn-doped SnO2/Zn2SnO4 nanocomposites were prepared via a two-step hydrothermal synthesis method. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-vis diffuse reflection spectroscopy, and adsorption-desorption isotherms. The results of FESEM and TEM showed that the as-prepared Zn-doped SnO2/Zn2SnO4 nanocomposites are composed of numerous nanoparticles with the size ranging from 20 nm to 50 nm. The specific surface area of the as-prepared Zn-doped SnO2/Zn2SnO4 nanocomposites is estimated to be 71.53 m2/g by the Brunauer-Emmett-Teller (BET) method. The photocatalytic activity was evaluated by the degradation of methylene blue (MB), and the resulting showed that Zn-doped SnO2/Zn2SnO4 nanocomposites exhibited excellent photocatalytic activity due to their higher specific surface area and surface charge carrier transfer.

Sonochemical Synthesis, Characterization, and Photocatalytic Activity of N-Doped TiO2 Nanocrystals with Mesoporous Structure

N-Doped TiO2 nanocrystals were synthesized via a simple sonochemical route, using titanium tetrachloride, aqueous ammonia, and urea as starting materials. The as-synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with an energy dispersion X-ray spectrometer (EDS), transmission electron microscopy (TEM), UV-vis diffuse reflection spectroscopy, Raman spectroscopy, and nitrogen adsorption-desorption isotherms. The results of TEM and nitrogen adsorption-desorption showed that the average size and specific surface area of the as-synthesized nanocrystals are 10 nm and 107.2 m2/g, respectively. Raman spectral characterization combined with the results of XRD and EDS revealed that N dopant ions were successfully doped into TiO2. Compared with pure TiO2, the adsorption band edge of N-doped TiO2 samples exhibited an obvious red shift to visible region. The photocatalytic activities were evaluated by the degradation of Rhodamine B (RhB) under visible light, and the results showed that the N-doped TiO2 sample synthesized by an optimal amount of urea exhibited excellent photocatalytic activity due to its special mesoporous structure and the incorporation of nitrogen dopant ions.

Carbon Nitride Decorated Ball-Flower like Co3O4 Hybrid Composite: Hydrothermal Synthesis and Ethanol Gas Sensing Application

Recently, semiconducting metal oxide (SMO) gas sensors have attracted the attention of researchers for high conductivity, labile features by environment, low cost, easy preparation, etc. However, traditional SMOs have some defects such as higher operating temperature and lower response value, which greatly limit their application in the field of gas sensor. In this work, the carbon nitride decorated ball-flower like Co3O4 composite was successfully synthesized via a facile hydrothermal method, the composition and morphology of the as-synthesized samples were studied by the techniques of X-ray powder diffraction (XRD), Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR) and N2-sorption. As a consequence, the pure Co3O4 and the carbon nitride decorated Co3O4 both possess ball-flower like structure, and the as-synthesized carbon nitride decorated Co3O4 composite exhibits significant sensing properties to ethanol which is 1.6 times higher than that of pure Co3O4, furthermore, the composite possesses high selectivity and stability towards ethanol detection.

A Facile Approach for the Synthesis of Zn2SnO4/BiOBr Hybrid Nanocomposites with Improved Visible-Light Photocatalytic Performance

In this study, a novel Zn2SnO4/BiOBr hybrid photocatalyst was prepared via a mild hydrothermal synthesis combined with a chemical deposition method. The morphological structure, chemical composition, crystal structure, and optical properties were comprehensively characterized by a series of measurement techniques. Morphological observation showed that fine Zn2SnO4 nanoparticles were anchored on the nanoplate surface of a flower-like BiOBr 3D hierarchical structure. The experimental results of UV-vis diffuse reflection spectroscopy revealed that the visible-light absorptive capacity of the Zn2SnO4/BiOBr hybrid photocatalyst was promoted, as compared to that of pure Zn2SnO4. Evidenced by electro-negativity theoretical calculation, Zn2SnO4 and BiOBr possessed matched band edges for accelerating photogenerated charge separation at the interface. The Zn2SnO4/BiOBr hybrid photocatalyst exhibited enhanced photocatalytic performance in the degradation of Rhodamine B (RhB) under visible light irradiation. According to the band energy structure and the experimental results, the enhanced photocatalytic performance was ascribed to the improved visible-light absorptive capacity and the contact interface between Zn2SnO4 nanoparticles and BiOBr nanoplates, being able to favor the prompt charge migration and suppress the recombination of photogenerated carriers in the hybrid system.

Synthesis, characterization and thermal stability of CeO2 stabilized ZrO2 ultra fine nanoparticles via a sol-gel route

CeO2 stabilized ZrO2 ultra fine nanoparticles were successfully synthesized via a simple and effective sol-gel synthetic approach by using zirconylchloride octahydrate, cerium nitrate hexahydrate, and citric acid as starting materials. A series of techniques, including X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and N2-sorption analysis, were used to characterize the structure and morphology of the as-prepared samples. XRD studies indicate that the as-synthesized sample is of well crystallized tetragonal phase of CeO2 stabilized ZrO2 with high purity. TEM images show that the as-synthesized sample is composed of a large number of fine dispersive nanoparticles with an average size about 10 nm. The as-synthesized tetragonal CeO2 stabilized ZrO2 sample was heated at different temperatures in order to evaluate its thermal stability. The exprimental results reveal that the as-synthesized tetragonal CeO2 stabilized ZrO2 sample exhibits excellent stability without the occurrence of phase transformation.

Controlled Synthesis of Water-Soluble NaYF4:Yb3+, Er3+ Nanoparticles with Surfactant Dependent Properties

Water-soluble NaYF4:Yb3+, Er3+ nanoparticles (NPs) are successfully prepared by a solvothermal reaction using branched polyethylenimine (PEI) with different chain lengths as the surfactants in a water/diethylene glycol (DEG) mixed solution. It is shown that the size of NaYF4 NPs prepared with high molecular weight PEI (HPEI) is smaller than that of the NPs prepared with low molecular weight (LPEI), while small-sized NPs exhibit more intense upconversion luminescence intensities than large-sized NPs in the same excitation power of 980 nm. It is found that HPEI is conducive to the formation of smaller NP with high crystallinity. Small-sized NaYF4:Yb3+, Er3+ NPs with intense upconversion luminescence and improved crystallinity were related to their growth process. A possible growth mechanism of the samples is proposed. The results of this study can provide new insights into the controlled synthesis of novel NPs.