Wan Guo

Fabrication of Z-scheme plasmonic photocatalyst Ag@AgBr/g-C3N4 with enhanced visible-light photocatalytic activity

A series of Ag@AgBr grafted graphitic carbon nitride (Ag@AgBr/g-C3N4) plasmonic photocatalysts are fabricated through photoreducing AgBr/g-C3N4 hybrids prepared by deposition-precipitation method. The phase and chemical structures, electronic and optical properties as well as morphologies of Ag@AgBr/g-C3N4 heterostructures are well-characterized. Subsequently, the photocatalytic activity of Ag@AgBr/g-C3N4 is evaluated by the degradation of methyl orange (MO) and rhodamin B (RB) under visible-light irradiation. The enhanced photocatalytic activity of Ag@AgBr/g-C3N4 compared with g-C3N4 and Ag@AgBr is obtained and explained in terms of the efficient visible-light utilization efficiency as well as the construction of Z-scheme, which keeps photogenerated electrons and holes with high reduction and oxidation capability, evidenced by photoelectrochemical tests and free radical and hole scavenging experiments. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of MO is put forward.

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.

Morphology-controlled preparation and plasmon-enhanced photocatalytic activity of Pt–BiOBr heterostructures

Pt-BiOBr nanosheets, microflowers, microspheres and sphere-like microflowers are controllably fabricated via a hydro(solvo)thermal treatment-photodeposition route and adjusting Br sources and solvents in the preparation systems. The simulated sunlight and visible-light photocatalytic properties of various morphological Pt-BiOBr heterostructures are evaluated by the degradation of two aqueous light insensitive organic pollutants, p-nitrophenol (PNP) and tetrabromobisphenol-A (TBBPA), and the relationship between the morphological characteristics and photocatalytic properties of the Pt-BiOBr is revealed accordingly. The sphere-like Pt-BiOBr microflowers and microspheres show considerably higher photocatalytic activity with respect to their microflowers and nanosheets counterparts, and their activity outperforms P25 TiO2. This excellent photoactivity is explained in terms of unique performance of BiOBr and plasmonic metal nanoparticles as well as fascinating morphological characteristics. The Pt-BiOBr heterostructures can be reused four times without obvious activity loss.

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.