Shengtian Huang

Enhanced separation efficiency of photo-induced charge pairs and sunlight-driven photocatalytic performance of TiO 2 prepared with the assistance of NH 4 Cl

The photocatalytic performance of TiO2 is significantly limited by its high recombination rate of photo-generated charge carriers, and therefore it is essential to further boost the photocatalytic activity of TiO2. In this paper, to enhance the separation efficiency of the photo-generated charge carriers by surface state regulation, a series of TiO2 photocatalysts were prepared by sol–gel method with the assistance of NH4Cl and studied by the Brunauer-Emmet Teller method, X-ray diffraction patterns, UV-VIS diffuse reflectance spectra, scanning electron microscopy with energy dispersive spectroscopy and surface photovoltage spectroscopy. The relative amount of •O2− was measured using nitrotetrazolium blue chloride (NBT) method. The photocatalytic activities of the samples under the simulated sunlight irradiation were investigated using Rhodamine B as the model dye. The results reveal that all the samples prepared with the assistance of NH4Cl display better photocatalytic activity than the reference TiO2 and the enhancement mechanism was proposed.Graphical abstract

Fabrication of Dy-doped BiVO4 with Enhanced Solar Light Photocatalytic Performance

BiVO4 and Dy-doped BiVO4 photocatalysts with different molar ratio of Dy/Bi (1%, 2%, 3%, and 4%) were prepared by a sol–gel method and characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopic (XPS) techniques, and surface photovoltage spectroscopy (SPS), respectively. The photocatalytic performance for decolorization of rhodamine B (RhB) aqueous solution under solar light was evaluated, the results show that Dy-doped BiVO4 with about 2%Dy possesses the best photocatalytic activity and the underlying mechanism is suggested.

Hydrolytic activity of μ-alkoxide/acetato-bridged binuclear Cu(II) complexes towards carboxylic acid ester

AbstractTwo μ-alkoxide/acetate-bridged small molecule binuclear copper(II) complexes were synthesized, and used to promote the hydrolysis of a classic carboxylic acid ester, p-nitrophenyl picolinate (PNPP). Both binuclear complexes exhibited good hydrolytic reactivity, giving rise to ca. 15547- and 17462-fold acceleration over background value for PNPP hydrolysis at neutral conditions, respectively. For comparing, activities of the other two mononuclear analogues were evaluated, revealing that binuclear complexes show approximately 150- and 171-fold kinetic advantage over their mononuclear analogues. Graphical AbstractThis study reports the hydrolysis of p-nitrophenyl picolinate (PNPP) with increase of rate acceleration up to four orders of magnitude by two μ-alkoxide/acetato-bridged binuclear copper(II) complexes when compared to uncatalysed reaction. Furthermore, the two binuclear complexes were more active than their mononuclear analogues in the catalytic hydrolysis of PNPP.

Fabrication and Improved Photocatalytic Performance of Pd/α-Fe2O3

Effective Pd decorated α-Fe2O3 photocatalysts with different Pd amount (Pd/Fe) were prepared by photodeposition method. The photocatalysts prepared were characterized by X-ray diffraction (XRD) and UV/vis diffuse reflectance spectroscopy (DRS). The separation efficiency of photogenerated charges was investigated using ammonium oxalate as scavenger. The photocatalytic activity of catalysts was evaluated by decolorization of methyl orange aqueous solution under ultraviolet light irradiation. The relationship between Pd loading and the photocatalytic performance was discussed and the optimization of the Pd/α-Fe2O3 composites was obtained. The result shows that Pd decorated Fe2O3 with 3% Pd (Pd/Fe) possesses the best photocatalytic activity.

Enhanced Photo-induced Charge Separation and Simulated Solar Photocatalytic Activity of α-Fe2O3/BiOCl Prepared In-situ

Abstract In this paper, α-Fe2O3/BiOCl composites were in-situ prepared by a hydrothermal routine and characterized by BET surface area, X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and surface photovoltage spectroscopy (SPS), respectively. The separation efficiency of photo- induced charges was investigated using benzoquinone (BQ) as scavenger. The relationship between α- Fe2O3 loading and the photocatalytic performance was investigated. When the molar ratio of Fe/Bi is 1/3, the composite material exhibits higher photocatalytic performance than the pure α-Fe2O3 and BiOCl towards decolorization of Methyl Orange (MO) aqueous solution under the simulated sun light irradiation. The enhanced mechanism was also discussed.

Enhanced Photocatalytic Activity of Bi-doped α-Fe2O3

Abstract Bi-doped α-Fe2O3 photocatalysts with different molar ratios of Bi/Fe (1%, 2%, and 3%) were prepared by a facile parallel flow co-precipitation method. The photocatalysts were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy and scanning electron microscope (SEM). The separation efficiency of photo-generated charges was investigated using benzoquinone (BQ) as scavenger. The effect of Bi doped on the photocatalytic performance was discussed. The results show that Bidoped α-Fe2O3 photocatalyst exhibits higher photocatalytic performance toward decolorization of methyl orange (MO) aqueous solution than pure α-Fe2O3 under both ultraviolet light and simulated solar light irradiation. The optimization of Bi-doped α-Fe2O3 photocatalyst was obtained. The enhanced mechanism was also discussed.

Studies on p-Nitrophenyl Picolinate (PNPP) Cleavage by Mono-Schiff Base Complexes with Aza-Crown Ether or Morpholino Pendants in CTAB Micellar Solution

Two mono-Schiff base manganese (III) and cobalt (II) complexes with benzo-10-aza-crown ether pendants , and the analogous with morpholino pendants have been employed as models to mimic hydrolase in p-nitrophenyl picolinate (PNPP) in the buffered CTAB micellar solution. The kinetics and the mechanism on PNPP hydrolysis catalyzed by these complexes were investigated. The kinetic mathematical model of PNPP cleavage catalyzed by these complexes was proposed. The relative kinetic and thermodynamic parameters were determined. The effects of complexes structure and reactive temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results showed that the rate for the catalytic PNPP hydrolysis was increased following the increase of pH of the buffered CTAB micellar solution; four complexes can efficiently accelerate the catalytic cleavage of PNPP in the buffered CTAB micellar solution. Compared with the crown-free analogous and , the crowned Schiff base complexes exhibit more high catalytic activity for promoting PNPP hydrolysis. The pseudo-first-order-rate ( k obs ) for the PNPP hydrolysis catalyzed by the complex in the CTAB micellar solution is 2.02 × 104 times than that of PNPP spontaneous hydrolysis in water at pH = 7.00, 25°C, [S] = 2.0 × 10−4 mol dm−3.

Effect of SiO2 Content on the Catalytic Performance of SiO2-TiO2 Composite Photocatalyst

Abstract SiO2-TiO2 composite photocatalysts were synthesized by sol-gel method with different SiO2 content (mol%). The specific surface area, structure, the band gap, the relative surface hydroxyl content and the photo-induced charge separation rate of the photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, Xray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (DRS), and surface photovoltage spectroscopy (SPS), respectively. The results show that the presence of SiO2 increases the specific surface area and the surface hydroxyl content, and influences the separation rate of photoinduced charge. The photocatalytic performance of SiO2-TiO2 for decolorization of methyl orange (MO) aqueous solution was investigated, the results show that SiO2-TiO2 composite photocatalyst with 16.7% SiO2 (mol%) possesses the best photocatalytic activity among the experimented compositions and the underlying mechanisms are discussed.

Enhanced Photocatalytic Activity of Y and Pd-co-doped Bi2O3 Prepared by Parallel Flow Co-precipitation Method

Abstract In this paper, Y and Pd co-doped Bi2O3 photocatalysts with different molar ratios between Y and Pd were prepared by a facile parallel flow co-precipitation method. The photocatalysts prepared were characterized by Brunauer- Emmett-Teller method (BET), X-ray diffraction (XRD), UV/Vis diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM), and surface photovoltage (SPV). The Y and Pd co-doped Bi2O3 photocatalysts exhibit higher photocatalytic performance towards de-colorization of methyl orange (MO) aqueous solution than undoped Bi2O3 under UV light and simulated sun light irradiation, and the underlying reason is discussed.

Effects of Various Schiff Base Ligands and Micelles on the Hydrolytic Kinetics of p-Nitrophenyl Picolinate

In this article, the effects of different micelles and Schiff base ligands on the hydrolytic kinetics of p-nitrophenyl picolinate (PNPP) were evaluated. The results reveal that the biggest rate enhancement for PNPP hydrolysis was given in Gemini 16-6-16 micellar solution relative to other four reaction media, that is, cetyltrimethylammonium bromide (CTAB), n-lauroylsarcosine sodium (LSS), polyoxyethylene (23) lauryl ether (Brij35) and pure buffer. Moreover, the hydrolytic rates of PNPP in other four media decreased in the order LSS > CTAB > Buffer > Brij35. The structural effects of Mn(III) catalysts clearly testify that a relatively open active site facilitates the formation of reactive substrate-catalyst complex.