Shengqu Zhang

Preparation and enhanced visible-light photocatalytic activity of graphitic carbon nitride/bismuth niobate heterojunctions

A series of graphitic carbon nitride/bismuth niobate (g-C3N4/Bi5Nb3O15) heterojunctions with g-C3N4 doping level of 10-90 wt% were prepared by a facile milling-heat treatment method. The phase and chemical structures, surface compositions, electronic and optical properties as well as morphologies of the prepared g-C3N4/Bi5Nb3O15 were well-characterized. Subsequently, the photocatalytic activity and stability of g-C3N4/Bi5Nb3O15 were evaluated by the degradation of aqueous methyl orange (MO) and 4-chlorophenol (4-CP) under the visible-light irradiation. At suitable g-C3N4 doping levels, g-C3N4/Bi5Nb3O15 exhibited enhanced visible-light photocatalytic activity compared with pure g-C3N4 or Bi5Nb3O15. This excellent photocatalytic activity was revealed in terms of the extension of visible-light response and efficient separation and transportation of the photogenerated electrons and holes due to coupling of g-C3N4 and Bi5Nb3O15. Additionally, the active species yielded in the pure g-C3N4- and g-C3N4/Bi5Nb3O15-catalyzed 4-CP photodegradation systems were investigated by the free radical and hole scavenging experiments.

Efficient degradation of tetrabromobisphenol A by heterostructured Ag/Bi5Nb3O15 material under the simulated sunlight irradiation.

Heterostructured metallic silver-layered bismuth niobate two-component system (Ag/Bi(5)Nb(3)O(15)) was developed for the first time by a mild hydrothermal method combined with photodeposition. The Ag/Bi(5)Nb(3)O(15) exhibited single-crystalline orthorhombic structure with small particle size (50-200 nm) and octahedral as well as sheet-like shape; additionally, it possessed photoresponse in both UV and visible region. As a novel alternative photocatalysts to TiO(2), the photocatalytic activity of the Ag/Bi(5)Nb(3)O(15) was evaluated by the degradation of tetrabromobisphenol A, a member from the family of the brominated flame retardant, under solar simulating Xe lamp irradiation, and enhanced photocatalytic activity in compared to Bi(5)Nb(3)O(15) itself and Degussa P25 was obtained.

One‐Step Preparation of Efficient and Reusable SO42−/ZrO2‐Based Hybrid Solid Catalysts Functionalized by Alkyl‐Bridged Organosilica Moieties for Biodiesel Production

A series of mesoporous sulfated zirconia materials functionalized by alkyl-bridged organosilica moieties (SO(4)(2-)/ZrO(2)-SiO(2)(R) with various S/Si or Zr/Si molar ratios and R=CH(2)CH(2) or C(6)H(4)) were developed by a one-step co-condensation technique combined with hydrothermal treatment with the aid of a triblock copolymer surfactant (P123). The structures, morphologies, porosities, and acid properties of the materials were well characterized. Subsequently, the catalytic performances (activity and stability) of SO(4)(2-)/ZrO(2)-SiO(2)(R) were evaluated by the transesterification of both pure triglyceride (tripalmitin) and low-cost virgin plant oil (Eruca sativa Gars. oil) with methanol for biodiesel production under mild conditions (atmospheric pressure, 65 °C), and the enhanced catalytic activity with respect to alkyl-free sulfated zirconia was obtained. This excellent catalytic activity was explained in terms of the inherent Brønsted acidity, well-defined mesoporosity, and increased hydrophobicity of the as-prepared, hybrid, solid acid catalyst.

Design of mesoporous SO42−/ZrO2–SiO2(Et) hybrid material as an efficient and reusable heterogeneous acid catalyst for biodiesel production

Mesoporous sulfated zirconia material functionalized by ethane-bridged organosilica moieties was prepared in a single step. Compared with alkyl-free sulfated zirconia materials, the as-prepared hybrid catalyst showed much higher catalytic activity towards biodiesel production from pure triglyceride as well as low-cost virgin plant oil.

Visible light-driven degradation of tetrabromobisphenol A over heterostructured Ag/Bi5Nb3O15 materials

A mild wet chemical synthesis route, hydrothermal treatment–photodeposition, was developed to obtain a series of heterostructured metallic silver/bismuth niobate (Ag/Bi5Nb3O15) hybrid materials with a single-crystalline orthorhombic layered structure and photoresponse in both the UV and visible light region. As a novel alternative photocatalyst to TiO2, the photocatalytic activity of as-prepared Ag/Bi5Nb3O15 was evaluated by the degradation of an aqueous tetrabromobisphenol A (TBBPA, a member of thebrominated flame retardant family) under visible light irradiation (400 nm < λ < 680 nm and 420 nm < λ < 680 nm). Additionally, the influence of initial pH in the reaction system on TBBPA degradation was investigated. The excellent photocatalytic activity of the Ag/Bi5Nb3O15 materials was explained, and the degradation pathway of an aqueous TBBPA catalyzed by the Ag/Bi5Nb3O15 under the visible light irradiation was proposed.

Template-free and morphology-controlled hydrothermal growth of single-crystalline Bi12TiO20 with excellent simulated sunlight photocatalytic activity

Single-crystalline bismuth titanates (Bi12TiO20) with the cubic phase and various morphologies (flower-, belt-, tetrahedral-like) were controllably fabricated by using a mild template-free hydrothermal process. The samples were fully characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM, nitrogen porosimetry measurement, UV-vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The influence of the solvent and the concentration of NO3− in the reaction system on the crystallinity and morphology of the Bi12TiO20 samples was investigated in detail. Bi12TiO20 crystals were used as the sunlight-driven photocatalysts to degrade aqueous dye methyl orange (MO) and p-nitrophenol (PNP), and the influence of Bi12TiO20 morphology on the photocatalytic activity was discussed. Finally, the recyclability of Bi12TiO20 was evaluated through three consecutive runs.

Morphology-controlled preparation and enhanced simulated sunlight and visible-light photocatalytic activity of Pt/Bi5Nb3O15 heterostructures

Plate- and octahedron-like Pt/Bi5Nb3O15 heterostructures are controllably prepared by a hydrothermal treatment method combined with photodeposition in the presence of different surfactants, i.e., cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP). The composition, structure, morphology, optical absorption properties, and textural properties of as-prepared Pt/Bi5Nb3O15 are well-characterized, and their simulated sunlight and visible-light photocatalytic activity is evaluated by the degradation of two typical organic pollutants, i.e., methyl orange (MO) and p-nitrophenol (PNP). Special attention is paid to investigate and explain the influence of the morphologies on the photocatalytic activity of the heterostructured Pt/Bi5Nb3O15.

Pore Morphology Control of Mesostructured SO42−/ZrO2‐Based Hybrid Catalysts Functionalized by Alkyl‐Bridged Organosilica Moieties for Biodiesel Production From Non‐Edible Oil

A series of mesostructured SO42−/ZrO2‐based hybrid materials functionalized with alkyl‐bridged organosilica species, forming SO42−/ZrO2‐SiO2(Ph/Et), were developed by using a single step co‐condensation technique with hydrothermal treatment in the presence of triblock copolymer surfactants. By tuning the molar ratios of the starting precursors, the types of surfactant and the preparation conditions, as‐prepared SO42−/ZrO2‐SiO2(Ph/Et) exhibited 2 D hexagonal p6mm, 3 D cubic Im3m and 3 D interconnected, worm‐hole‐like pore geometries. The mesostructure, morphology, porosity, and composition, as well as acid property of as‐prepared materials were characterized. As a novel, reusable, solid acid catalyst, the hybrid materials were applied for the biodiesel production from a non‐edible oil (Eruca sativa Gars. oil) under mild conditions; considerably high catalytic activity and stability were observed. Special attention was paid to the influences of the textural properties on the activity of SO42−/ZrO2‐SiO2(Ph/Et) materials to the target reaction.