Fengyan Ma

Mixed phase titania nanocomposite codoped with metallic silver and vanadium oxide: New efficient photocatalyst for dye degradation

Titania nanocomposite codoped with metallic silver and vanadium oxide was prepared by a one-step sol-gel-solvothermal method in the presence of a triblock copolymer surfactant (P123). The resulting Ag/V-TiO(2) three-component junction system exhibited an anatase/rutile (weight ratio of 73.8:26.2) mixed phase structure, narrower band gap (2.25 eV), and extremely small particle sizes (ca. 12 nm) with metallic Ag particles well distributed on the surface of the composite. The Ag/V-TiO(2) nanocomposite was used as the visible- and UV-light-driven photocatalyst to degrade dyes rhodamine B (RB) and coomassie brilliant blue G-250 (CBB) in an aqueous solution. At 1.8% Ag and 4.9% V doping, the Ag/V-TiO(2) system exhibited the highest visible- as well as UV-light photocatalytic activity; additionally, the activity of the three-component system exceeded that of Degussa P25, pure TiO(2), single-doped TiO(2) system (Ag/TiO(2) or V-TiO(2)) as well as P123-free-Ag/V-TiO(2) codoped system. The reasons for this enhanced photocatalytic activity were revealed.

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.

Transesterification of soybean oil to biodiesel catalyzed by mesostructured Ta2O5-based hybrid catalysts functionalized by both alkyl-bridged organosilica moieties and Keggin-type heteropoly acid

A series of Ta2O5-based hybrid catalysts functionalized by both alkyl-bridged organosilica fragments and the Keggin-type heteropoly acid, Ta2O5/Si(R)Si-H3PW12O40 (R = –CH2CH2- or –C6H4–), were prepared via a one-pot co-condensation method in the presence of a triblock copolymer surfactant (P123). The materials were well characterized by spectroscopy methods, X-ray diffraction analysis, transmission electron microscopy, and nitrogen physisorption measurement to confirm the structural integrity of the Keggin unit and alkyl-bridged organosilica units in the hybrid materials, to investigate the interaction between the Ta2O5 matrix and the organic or inorganic functionalities, and to test the mesostructure, morphology, and porosity of the materials. The materials were subsequently utilized as environmentally-friendly solid acid catalysts in the transesterification of soybean oil (containing 20 wt% myristic acid) with methanol to produce fatty acid methyl esters under atmosphere refluxing. Compared with bulk H3PW12O40 and alkyl-free H3PW12O40/Ta2O5, as-prepared Ta2O5/Si(R)Si-H3PW12O40 hybrid materials with suitable concentrations of bridging alkyl groups exhibited higher reactivity toward the target reaction. This enhanced acid-catalytic reactivity after the introduction of both acidic and hydrophobic functionalities within the Ta2O5 matrix is discussed. Finally, the reusability of the hybrid materials was evaluated through three catalytic runs.

Simulated sunlight photodegradation of aqueous phthalate esters catalyzed by the polyoxotungstate/titania nanocomposite

A series of porous polyoxotungstate/titania nanocomposites (PW(12)/TiO(2)) with particle size lower than 10nm and BET surface area of ca. 200 m(2)g(-1) was prepared by sol-gel chemistry combined with solvothermal treatment. The composites were successfully applied to the degradation of aqueous phthalate esters (PAEs) including di-n-butyl phthalate (DBP), diethyl phthalate (DEP), and dimethyl phthalate (DMP) under the simulated sunlight irradiation (lambda=320-680 nm) for the first time, and the conversion of DBP, DEP, and DMP reached to 98%, 84%, and 80%, respectively, after the simulated sunlight irradiation the suspension including PAE (5 mg L(-1), 100 mL) and PW(12)/TiO(2)-19.8 (100 mg) for 90 min. In addition, nearly total mineralization of DBP and DEP was realized by further increasing light irradiation time to 12h. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of PAEs was put forward.

Design of mesostructured H3PW12O40-silica materials with controllable ordered and disordered pore geometries and their application for the synthesis of diphenolic acid

A series of mesostructured H3PW12O40-silica materials were developed by using a single step co-condensation technique in the presence of nonionic oligomeric surfactant, C18H37(OCH2CH2)10OH (C18EO10, Brij76). By tuning the composition ratios of the starting precursors (mainly the molar ratios of water to the other materials) and the preparation conditions, the materials exhibited ordered two-dimensional (2D) hexagonal p6mm, three-dimensional (3D) hexagonal P63/mmc, and 3D disordered sponge-like pore geometries, respectively. The materials possessed unique textural properties including very large BET surface area (590–1050 m2 g−1), very high porosity (0.4–1.3 cm3 g−1), and well-distributed pore diameter (3.0–5.4 nm). As a novel type of reusable solid acid catalyst, as-prepared materials were applied for the synthesis of diphenolic acid (DPA) from biomass-derived platform molecule, levulinic acid (LA), under solvent-free condition, and special attention was paid to investigating the influences of the structural orderings, pore geometries, H3PW12O40 loadings, and template removal methods on the reactivity and selectivity of H3PW12O40-silica materials to the target reaction.

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.

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.