Papers by Author: Xiao Jing Wang

Abstract: Semiconductors showing high efficient photocatalytic activity have attracted great interest, because they provide a potential solution to many environmental pollution problems that humankind is currently facing. This work reports on the sol-gel synthesis of Na₂Ta₄O₁₁ nanocrystals and its photocatalytic performance toward Red G. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and the Barrett–Emmett–Teller technique. By modulating the synthetic condition, the sol-gel reaction yielded pure Na₂Ta₄O₁₁ nanocrystals with diameter of ~32 nm from the peak broadening of (006) plane using Scherrer formula. It is found that the as-prepared Na₂Ta₄O₁₁ nanocrystals showed a band gap energy of 3.63 eV, which is much smaller than that of Na₂Ta₄O₁₁ prepared by flux approach. The relative narrowed band gap energy of Na₂Ta₄O₁₁ nanocrystals may predict superior photocatalytic activity. By careful photocatalytic test, it is found that Na₂Ta₄O₁₁ nanocrystals showed excellent photocatalytic activity toward Red G. The photocatalytic degradation efficiency was estimated to be 94.0% within a time intervals of 40 minutes. Controlled experiment by adding active species scavengers gave evidence that the degradation of Red G is dominated by the oxidation reaction of the generated O₂^-∙ active species taking place on the surface of the photocatalyst.

Abstract: In this work, potassium tantalate (KTaO₃) particles were synthesized using a low-temperature hydrothermal method. The phase structure of samples prepared was performed by X-ray diffraction (XRD). The result revealed that it belongs to cubic crystal. The electrochemical behaviour of a KTaO₃ film coated electrode was investigated in 0.1 mol dm^-3 KCl containing 5 mmol dm^-3 K₃Fe (CN)₆ with cyclic voltgrammetry (CV). The CV results indicated that the KTaO₃ film coated electrode exhibited excellent electrochemical stability. The electrochemical reaction of K₃Fe (CN)₆ on the KTaO₃ film coated electrode was a diffusion-controlling process.

Abstract: Effects of zinc cations doping into wide band gap semiconductor photocatalysts of electronic structure, visible light response, and photo-absorbed mechanism were studied. A series of Zn-doped NaTaO3 catalysts were prepared by hydrothermal method. XRD results suggested that zinc were successfully doped into the NaTaO3 nanocrystal in the Zn2+ ions state. UV-vis diffuse reflectance spectra indicated no obvious red-shift was observed in the series of zinc doped NaTaO3 photo-catalysts. The simulation of energy band structure by density functional theory unfolded that d orbital of Zn2+ is lower than the Ta 5d and also O 2p orbital, thus it located at the lower energy region of the valence band. Therefore the substitution of Ta5+ ions by Zn2+ ions can not form an intermediate band (IB) between the top of the valence band (VB) and the bottom of conduct band. Meanwhile Zn species can become the recombination centers of photoinduced electrons and holes. Thus, the quickly recombination of e--h+ pairs is one of the most significant factors which deteriorate the photoactivity of Zn-doped NaTaO3

Abstract: Europium doped tantalum oxide (europium-Ta₂O₅) particles were synthesized with a low temperature hydrothermal method. The electrochemical behaviour of an europium-Ta2O5 film electrode in 0.1 mol dm^-3 KCl solution containing 5 mmol dm^-3 K₃Fe(CN)₆ was investigated using cyclic voltgrammetry (CV). The CV results indicated that the europium-Ta₂O₅ film electrode exhibited good stable and reversible electrochemistry properties. The electrochemical reaction of K₃Fe(CN)₆ was a diffusion-controlling process on the europium-Ta₂O₅ film electrode. The europium-Ta₂O₅ particles might have potential applications in electrochemical fields.

Abstract: The article reported the reduction of methylene blue (abbreviated as MB) by ascorbic acid (abbreviated as AA) in aqueous solution. The kinetics study revealed that the reduction proceeds of MB by AA was the pseudo first order reaction. In addition, the electrochemical property of reductant AA was investigated by cyclic voltammetry (CV). The CV result indicated that the electrochemical oxide of AA was diffusion controlling at glass carbon electrode (GCE).

Abstract: A new charge-transfer coordination compound [(C5S5H3CH2O)4Ni](FeCp2)0.84 was synthesized in this work. The molecular formula of the coordination compound was confirmed by elementary analysis and ICP. The structure of this compound was defined by 1HNMR, IR and UV-Vis. Electrochemical properties of the new compound were studied by cyclic voltammetry (CV). Electrical property was tested by four probe methods with R-T curve.

Abstract: Electronic structure and optical properties of non-metals (N, S, F, P, Cl) -doped cubic NaTaO3 were investigated systematically by density functional theory (DFT). The results showed that the substitution of (N, S, P, Cl) for O in NaTaO3 was effective in narrowing the band-gap relative to the F-doped NaTaO3. The larger red shift of the absorption edge and the higher visible light absorption at about 520 nm were found for the (N and P)-doped NaTaO3. The excitation from the impurity states to the conduction band may account for the red shift of the absorption edge in an electron-deficiency non-metal doped NaTaO3. The obvious absorption in the visible light region for (N and P)-doped NaTaO3 provides an important guidance for the design and preparation of the visible light photoactive materials.