Novel NiTiO3/Ag3VO4 composite with enhanced photocatalytic performance under visible light

A novel NiTiO₃/Ag₃VO₄ composite with type-II band alignment was prepared using a modified Pechini/precipitation method. The FESEM image of the NiTiO₃/Ag₃VO₄ heterostructure reveals the dispersion of small NiTiO₃ particles on the Ag₃VO₄ surfaces, indicating the close interfacial connection between NiTiO₃ and Ag₃VO₄. The heterojunction shows remarkably higher photocatalytic activity than pure NiTiO₃ and Ag₃VO₄ due to an increase in light harvesting efficiency and an efficient electron–hole separation being induced by the suitably matching conduction and valence band levels. Based on the VB-XPS and UV–vis DRS results, a possible electron–hole transfer mechanism at the NiTiO₃/Ag₃VO₄ interface is proposed.     

Fabrication of ternary p-n heterostructures AgCl/Ag2O/NaTaO3 photocatalysts: Enhanced charge separation and photocatalytic properties under visible light irradiation

Ternary p-n heterostructures photocatalysts of AgCl/Ag₂O/NaTaO₃ were synthesized via a simple method and the crystal structure characterized by X-ray diffraction (XRD). The morphology of the photocatalysts were characterized by scanning electron microscopy and transmission electron microscopy. The composition of the photocatalysts was studied by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscope. The photocatalytic activity of the AgCl/Ag₂O/NaTaO₃ photocatalysts was evaluated using the degradation of Rhodamine B. The AgCl/Ag₂O/NaTaO₃ photocatalysts showed higher visible light activity than the pure NaTaO₃ and Ag₂O/NaTaO₃ photocatalysts. Additionally, the photocatalytic mechanism was that the rapidly separation of photoinduced electrons and holes resulted the enhancement of photocatalytic activity.     

SDBS辅助合成Y2O3/Ag3VO4光催化剂及其催化可见光降解罗丹明B

以V2O5, AgNO3和Y(NO3)3×6H2O为原料、十二烷基苯磺酸钠为辅助剂,采用直接沉淀法和浸渍法制备单斜晶相Ag3VO4和Y2O3/Ag3VO4复合催化剂,表征了产物的结构和形貌,并分析了其形成机理;在可见光下研究了其催化可见光降解罗丹明B(RhB)的性能. 结果表明,所得Y2O3/Ag3VO4复合催化剂吸收边相对纯相Ag3VO4发生红移,禁带宽度减小至1.83 eV,电子-空穴对复合几率降低,对RhB有较好的可见光催化活性和稳定性,可见光照射15 min后,0.08 g 3% Y2O3/Ag3VO4催化200 mL 8 mg/L RhB溶液的降解率达94.2%.     

The highly active saddle-like Ag3PO4 photocatalyst under visible light irradiation

Saddle-like Ag₃PO₄ particles of tetrahedron structure were successfully synthesized using a co-precipitation method by mixing H₃PO₄ ethanol solution and AgNO₃ ethanol aqueous solution, where the percentage of ethanol in AgNO₃ ethanol aqueous solution was varied at 0, 50, 80, 90 and 100% (v/v). The photocatalytic performance of the synthesized samples was evaluated by photodegradation of Rhodamine B (RhB) under blue light irradiation (λ = 455 nm). The results showed that the morphology of the Ag₃PO₄ particles greatly changed depending on the ethanol content in the reaction solution. Excellent photocatalytic activity was observed at 80% (v/v) of ethanol, where the Ag₃PO₄ showed saddle-like morphology derived from the tetrahedron structure.     

热/可见光联合活化单过氧硫酸氢盐光敏降解罗丹明B

采用可见光/热/单过氧硫酸氢盐(PMS)体系氧化降解罗丹明B。在可见光条件下,考察了溶液温度、p H值、PMS初始浓度对罗丹明B降解动力学的影响。结果表明,在暗反应条件下,升高溶液温度,促进罗丹明B的降解,联合可见光光照,罗丹明B的降解率进一步增大。在酸性条件下,溶液p H值对罗丹明B降解的影响并不显著。在PMS初始浓度保持一定的范围内,罗丹明B的降解率与PMS初始浓度呈现出正相关关系。     

微波辅助Fe_3O_4/H_2O_2类Fenton法处理罗丹明B废水

采用纳米Fe3O4作为催化剂,H2O2为氧化剂,组成多相类Fenton试剂,与微波联合处理罗丹明B(Rh B)染料废水。反应在300W微波反应器中进行,系统研究了H2O2浓度,Fe3O4用量,反应时间,反应温度及催化剂循环使用等条件对罗丹明B脱色率的影响。结果表明,在pH值为4,罗丹明B浓度为100 mg/L,反应温度为80℃,反应时间为5min,H2O2用量为5.0 mL/L,Fe3O4用量为1.25 g/L时,微波辅助条件下罗丹明B脱色率达到100%。此外,催化剂六次循环实验表明,磁性催化剂非常稳定,可重复使用,且易回收。实验表明微波加热与Fe3O4/H2O2类Fenton反应的联合产生了良好的协同效果,该联合工艺可大大提高废水中有机物的处理效果。     

Photocatalytic O2 evolution under visible light irradiation on BiVO4 in aqueous AgNO3 solution

BiVO₄ with a 2.3 eV band gap showed an activity for O₂ evolution from aqueous solutions containing Ag⁺ as an electron scavenger under visible light irradiation (λ > 520 nm). The quantum yield was 0.5% at 450 nm. This revised version was published online in July 2006 with corrections to the Cover Date.     

Y2O3-Bi2O3可见光催化降解甲基橙

采用固相合成法制备了Y<,2>O<,3>-Bi<,2>O<,3>复合可见光催化剂,用XRD、DRS对复合催化剂进行了表征.以甲基橙为模拟废水,在日光色镝灯光照下,研究了废水浓度、催化剂投加量、温度、pH等对Y<,2>O<,3>-Bi<,2>O<,3>光催化活性的影响.实验结果表明:在甲基橙质量浓度为20 mg/L、Y<...     

Photocatalytic degradation of bisphenol A by Ag3PO4 under visible light

Ag₃PO₄ catalysts exhibited excellent photocatalytic performance in the degradation and the mineralization of bisphenol A, displaying considerably higher photocatalytic activity than N–TiO₂ under visible light (λ > 420 nm). The trapping effects of different scavengers and spectrophotometric results proved that the oxidation of bisphenol A mainly occurred at photogenerated holes on the Ag₃PO₄ surface, along with a two-electron reduction of dissolved oxygen to H₂O₂.     

Photocatalytic reduction of carbon dioxide using Co3O4 nanoparticles under visible light irradiation

Photocatalytic reduction of carbon dioxide under visible light irradiation was carried out with Co₃O₄ powders suspended in water. A Pyrex glass batch reactor of 10mL in volume was used with a 21 W LED lamp of 510 to 620 nm in wave length as light source, and the reaction time was held at 4 h. The major products were formic acid and formaldehyde; the production rates were 4.53 μmol g^?1h^?1 and 0.62 μmol g^?1h^?1 for formic acid and formaldehyde, respectively. Carbon monoxide and methane were detected in trace amounts. The occurrence of the photo-reduction with Co₃O₄ is against the expectation from the valence band edge of Co₃O₄ in the literature. Possible causes for the contradictory result are discussed.     

Preparation of hollow porous Cu2O microspheres and photocatalytic activity under visible light irradiation

Cu₂O p-type semiconductor hollow porous microspheres have been prepared by using a simple soft-template method at room temperature. The morphology of as-synthesized samples is hollow spherical structures with the diameter ranging from 200 to 500 nm, and the surfaces of the spheres are rough, porous and with lots of channels and folds. The photocatalytic activity of degradation of methyl orange (MO) under visible light irradiation was investigated by UV-visible spectroscopy. The results show that the hollow porous Cu₂O particles were uniform in diameters and have an excellent ability in visible light-induced degradation of MO. Meanwhile, the growth mechanism of the prepared Cu₂O was also analyzed. We find that sodium dodecyl sulfate acted the role of soft templates in the synthesis process. The hollow porous structure was not only sensitive to the soft template but also to the amount of reagents.     

Systematic studies of Bi2O3 hierarchical nanostructural and plasmonic effect on photoelectrochemical activity under visible light irradiation

The effect of Ag plasmonic nanowire layers on the hierarchical nanostructure of Bi₂O₃ photoelectrodes for water splitting under visible light irradiation was studied for the first time. In addition, the impact of various Bi₂O₃ nanostructures on light harvesting and generation of relative photocurrent have been investigated. The cubic structure of Bi₂O₃ was confirmed using X-ray diffraction analysis. Optical bandgaps of 2.14 and 2.30 eV have been achieved for the Bi₂O₃ nanoparticles and nanoflowers photoelectrodes (BP and BF), respectively. The photocurrent density (J) of the BP featuring Ag plasmonic layer photoelectrode (Ag/BP) was 6.47 mA cm⁻², and was higher than that of the BF featuring Ag plasmonic layer photoelectrode (Ag/BF), which was 4.33 mA cm⁻². These values were approximately 647 and 2165 times higher than those of BP and BF, respectively. However, the J value of BP was 2.13 mA cm⁻² higher than that of BF. The superior J values of Ag/BP and Ag/BF were attributed to the increased light absorption and reduced electron-hole recombination rate at the time scale beyond a few 10⁻¹² s, owing to the Ag nanowires. In addition, the plasmonic field was able to reduce the charge recombination rate of the nanostructured electrodes in reactor cells.     

A g-C3N4 supported graphene oxide/Ag3PO4 composite with remarkably enhanced photocatalytic activity under visible light

In this work, a ternary composite photocatalyst of graphitic carbon nitride (g-C₃N₄), graphene oxide (GO), and Ag₃PO₄ was prepared through a simple precipitation route, in which Ag₃PO₄ nanoparticles covered or wrapped with GO sheets are supported on g-C₃N₄ sheets. The composite photocatalyst displays enhanced absorption in the visible region, and exhibited superior photocatalytic activity compared with single-component or binary composite photocatalysts in the photocatalytic decomposition of Rhodamine B. The enhancement of photocatalytic activity could be attributed to the synergistic effect among them. The ternary composite also exhibited enhanced stability, but further efforts should be made to make it more stable.     

Preparation of Ag@AgI-intercalated K4Nb6O17 composite and enhanced photocatalytic degradation of Rhodamine B under visible light

In this study, a novel plasmonic photocatalyst, Ag@AgI intercalated layered niobate, was synthesized via a microwave-assisted ion-exchange method. The composite materials prepared were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray fluorescence spectrometry (XRF), Brunauer–Emmett–Teller (BET) and ultraviolet–visible diffuse reflection spectra (UV–vis). The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photocatalytic performance for the degradation of Rhodamine B (RhB) and up to 83% of RhB was degraded in 40 min under visible light irradiation. The mechanism of separation of the photo-generated electrons and holes at the K₄Nb₆O₁₇/Ag@AgI composite was discussed.     

Efficient photodegradation of phenol assisted by persulfate under visible light irradiation via a nitrogen-doped titanium-carbon composite

To realize the utilization of visible light and improve the photocatalytic efficiency of organic pollutant degradation in wastewater, a nitrogen-doped titanium-carbon composite (N-TiO₂/AC) prepared by sol-gel methods was applied in the photodegradation of phenol assisted by persulfate under visible light irradiation (named N-TiO₂/AC/PS/VIS). The results show that a synergistic effect exists between visible-light photocatalysis and persulfate activation. Compared with TiO₂/PS/VIS, the phenol degradation rate was found to be observably improved by 65% in the N-TiO₂/AC/PS/VIS system. This significant increase in degradation rate was mainly attributed to the following two factors: 1) The N and C doping can change the crystal structure of TiO₂, which extends the TiO₂ absorption wavelength range to the visible light region. 2) As an electron acceptor, PS can not only prevent electrons and holes from recombining with each other but can also generate strong oxidizing radicals such as ∙SO₄^– and ∙OH to accelerate the reaction dynamics. The process of phenol degradation was found to be consistent with the Langmuir pseudo-first-order kinetic model with an apparent rate constant k of 1.73 min^–1. The N-TiO₂/AC/PS/VIS process was proven to be a facile method for pollutant degradation with high pH adaptability, excellent visible-light utilization and good application prospects.     

Ag/AgBr/BiOBr hollow hierarchical microspheres with enhanced activity and stability for RhB degradation under visible light irradiation

Ag/AgBr/BiOBr hollow hierarchical microspheres were synthesized through a one-pot solvothermal process. The phase structure, morphology and optical property of the samples were characterized by XRD, SEM, XPS and DRS. Ag/AgBr/BiOBr hollow microspheres exhibited higher photocatalytic activity and improved stability than AgBr/BiOBr nanoplates for rhodamine B degradation under visible light irradiation. The enhanced activities of Ag/AgBr/BiOBr could be attributed to the hollow structure and Ag deposition, which is favorable for adsorption of reactants, enhancement of photoadsorption and transfer of photogenerated carriers. Ag deposition also prevented the decomposition of AgBr under light illumination and contributed to an improved stability.     

A unique Cu2O/TiO2 nanocomposite with enhanced photocatalytic performance under visible light irradiation

A unique Cu₂O/TiO₂ nanocomposite with high photocatalytic activity was synthesized via a two-step chemical solution method and used for the photocatalytic degradation of organic dye. The structure, morphology, composition, optical and photocatalytic properties of the as-prepared samples were investigated in detail. The results suggested that the Cu₂O/TiO₂ nanocomposite is composed of hierarchical TiO₂ hollow microstructure coated by a great many Cu₂O nanoparticles. The photocatalytic performance of Cu₂O/TiO₂ nanocomposite was evaluated by the photodegradation of methylene blue (MB) under visible light, and compared with those of the pure TiO₂ and Cu₂O photocatalysts synthesized by the identical synthetic route. Within 120 min of reaction time, nearly 100% decolorization efficiency of MB was achieved by Cu₂O/TiO₂ photocatalyst, which is much higher than that of pure TiO₂ (26%) or Cu₂O (32%). The outstanding photocatalytic efficiency was mainly ascribed to the unique architecture, the extended photoresponse range and efficient separation of the electron-hole pairs in the Cu₂O/TiO₂ heterojunction. In addition, the Cu₂O/TiO₂ nanocomposite also retains good cycling stability in the photodegradation of MB.