Reduced-graphene-oxide-wrapped BiOI-AgI heterostructured nanocomposite as a high-performance photocatalyst for dye degradation under solar light irradiation

Solar photocatalytic water treatment has emerged as a promising way to provide clean water. However, most traditional photocatalysts (TiO₂, ZnO, etc.) are active only under ultraviolet light and have high recombination rates of photoinduced electron-hole pairs; therefore, they are not sufficient to fulfill all of the demands of practical applications. This problem could be overcome by developing highly solar-light-active and durable heterostructured photocatalysts. In this study, a new solar-light-active heterostructured reduced graphene oxide (RGO)/BiOI/AgI photocatalyst was successfully fabricated through a simple precipitation method. The resultant heterostructured RGO/BiOI/AgI nanocomposite exhibited extraordinary photocatalytic performance in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The measured rate constant of the RGO/BiOI/AgI nanocomposite was six times higher than that of bare BiOI nanostructures. Its extraordinary capacity for harvesting full-spectrum light and long-term stability makes the RGO/BiOI/AgI nanocomposite a potential photocatalyst for environmental remediation.     

可见光照射下取代型杂多酸盐对染料的催化降解

将杂多酸(GaWmFen)负载到阴离子交换树脂(Resin)上,得到GaWmFen/Resin(GaWmFenR)固相光催化剂,在可见光的照射下,以罗丹明B(RhB)为模型化合物,含镓的GaWmFen/Resin(GaWmFenR)催化剂可以有效地活化H2O2降解染料RhB,随着铁原子的取代数目的增多,RhB浓度比降低的趋势加快,GaW9Fe3最快,C/C0降低0.937.在光照300 min 以后,体系的总有机碳(TOC)的变化趋于平缓,减少了0.15 mg.L-1.催化剂的8次重复试验结果表明GaWmFenR固相光催化剂易于分离,并且具有良好的稳定性,可以重复利用.     

Photobleaching of 1,3-diphenylisobenzofuran by novel phthalocyanine dye derivatives.

As part of a wider programme to identify novel photosensitizers for photodynamic therapy, the ability of a number of phthalocyanine dyes, including some novel copper phthalocyanine derivatives with a range of water solubilities, to produce potentially cytotoxic species in solution was examined. The experiments were performed in dimethylformamide using 1,3-diphenylisobenzofuran (DPIBF) as the scavenger. The study revealed that all the dyes tested produced DPIBF photobleaching on illumination in vitro, but with widely different (greater than 12x) rates. The possible correlation of DPIBF photobleaching rates with a number of the dyes' properties is discussed.     

Magnetic retrievable Ag/AgBr/ZnFe2O4 photocatalyst for efficient removal of organic pollutant under visible light

In the present work, a visible-light-driven Ag/AgBr/ZnFe₂O₄ photocatalyst has been successfully synthesized via a deposition–precipitation and photoreduction method. The crystal structure, chemical composition, morphology and optical properties of the as-prepared nanocomposites were characterized by X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscope, UV–vis diffuse reflectance spectroscopy and photoluminescence. The photocatalytic activities of the Ag/AgBr/ZnFe₂O₄ nanocomposites were evaluated through the photodegradation of gaseous toluene and methyl orange (MO) under visible light. The results revealed that the as-prepared Ag/AgBr/ZnFe₂O₄ nanocomposite exhibited excellent photocatalytic activity. The degrading efficiency of MO could still reach 90% after four cycles, and the Ag/AgBr/ZnFe₂O₄ nanocomposite could be recycled easily by a magnet. Additionally, the enhanced photocatalytic mechanism was discussed according to the trapping experiments, which indicated that the photo-generated holes (h⁺) and •O₂⁻ played important roles in photodegradation process. At last, a possible photocatalytic oxidation pathways of toluene was proposed based on the results of GC–MS. The Ag/AgBr/ZnFe₂O₄ composites showed potential application for efficient removal of organic pollutant.     

AgBr/nanoAlMCM-41 visible light photocatalyst for degradation of methylene blue dye

A novel photocatalytic material was synthesized by dispersion of AgBr in nanoAlMCM-41 material. The AgBr/nanoAlMCM-41 sample shows strong absorption in the visible region because of the plasmon resonance of Ag nanoparticles in AgBr/nanoAlMCM-41. The catalysts were characterized using XRD (X-ray diffraction), UV-visible diffused reflectance spectra (UV-vis DRS) and scanning electron microscopy (SEM). The photocatalytic activity and stability of the synthesized catalysts were evaluated for methylene blue (MB) degradation in aqueous solution in the presence of 200 W tungsten filament Philips lamp. Several parameters were examined, catalyst amount, pH and initial concentration of MB, AgBr loading. The effect of dosage of photocatalyst was studied in the range 0.05-1.00 g/L. It was seen that 0.1 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The support size was obtained about 9-100 nm. In the same way, the average size of AgBr nanoparticles was about 10nm before visible radiation. After visible radiation the average size of AgBr nanoparticles was about 25 nm.     

Photobleaching and mineralization of Orange II by oxone and metal-ions involving Fenton-like chemistry under visible light

Cu²⁺ and Fe³⁺ significantly improved the Orange II photobleaching and mineralization in the presence of oxone. In the presence of Cu²⁺ and Fe³⁺ the oxone needed for the photobleaching and total mineralization of the dye was determined along other solution parameters. In air, the photobleaching of Orange II in solution was observed to be complete within 60 min for Cu²⁺-ions and 30 min for Fe³⁺-ions showing a considerable faster kinetics with respect to other treatment systems reported until now. The transition metal-ions used seem to couple with oxone forming high oxidizing sulfate species. A reaction mechanism leading to Orange II photobleaching is suggested through a complex formation between the metal-ion and Orange II involves redox reactions activated by visible light.     

Remote activation of capsules containing Ag nanoparticles and IR dye by laser light

We present a novel method for remote release of an encapsulated material from polyelectrolyte capsules based on laser light illumination. Two different components were introduced in the polyelectrolyte shells of PAH/PSS capsules-either Ag nanoparticles or IR dye-to induce absorption of light. Under laser illumination the capsules containing Ag nanoparticles or IR dye were deformed or cut, thus providing a venue for remote release of encapsulated materials. The experiments were conducted with a low-power near-infrared continuous-wave laser diode.     

Visible-light-promoted organic dye catalyzed perfluoroalkylation of hydrazones under mild conditions

A general and facile visible-light-promoted organic dye catalyzed perfluoroalkylation of hydrazones has been developed using inexpensive and non-toxic Eosin Y as the photoredox catalyst under mild conditions. This reaction protocol exhibits synthetic simplicity, broad scope of substrates, and excellent functional group compatibility. A gram scale synthesis can be also facilitated with a satisfactory yield, which opens up the possibility of practical applications.     

Generation of low-molecular-weight organic compounds in water by titania photocatalyst under UV-Vis light radiation

We attempted to develop a new type titania photocatalyst that, when activated, responded in not only the ultraviolet rays region but also visible light radiation region by the new titania photocatalyst with the zirconia and nitrogen simultaneously introduced in the titania lattice. The decomposition performance of the standard organic compound in water by this new type titania photocatalyst nanoparticle was compared with the conventional type under both the ultraviolet ray and visible light radiation conditions. It was suggested that the low-molecular-weight organic compounds were also generated from the organic compound in water by the new type titania photocatalyst activities under the visible light radiation.     

Photodegradation of organic pollutants catalyzed by iron species under visible light irradiation

The green oxidation technology is the most economically attractive and environmentally friendly oxidation technique in the treatment of organic pollutants. Photocatalytic degradation of organic pollutants by iron species is a desired green oxidation technique due to using hydrogen peroxide or ideally molecular oxygen as oxidant and water as solvent. However, the system has some disadvantages. The reaction has to be performed in acidic conditions in order to avoid Fe ion precipitation and iron sludge will be accumulated in the reaction. Moreover, the utilization of H(2)O(2) means a high cost and risks in the storage and transportation and organic pollutants can not be completely mineralized. In this perspective, we report a systematic investigation of the improvement in the Fenton system for treatment of organic pollutants in water. Several strategies have been studied on the Fenton system for overcoming the above mentioned shortcomings and enhance the efficiency. For example, in order to extend the application of the Fenton system and perform it at neutral pH, iron complexes were used to replace the Fe(2+)/Fe(3+). Moreover, iron complexes have a strong absorption in the visible region, which leads to decomposition of colorless organic pollutants under visible light irradiation. Iron complexes with special structures can activate molecular O(2) instead of H(2)O(2) under mild conditions and the supported iron species maintains a high catalytic activity after repeated use and can be reused simply by filtration. Finally, prospects for further work required to be performed for its practical application is discussed.     

Photodegradation of orange II dye using p-n junction NiO/TiO2 composite,and assessment of its biological activities

The chemical reduction method was used to synthesize nickel oxide particles (NiO) and NiO supported on titanium dioxide (NiO/TiO₂ nanocomposite). The composites were characterized through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The morphological investigation showed that pseudocubic NiO are present in dispersed as well as agglomerated forms. Whereas NiO particles (<200 nm) are evenly deposited over the surface of TiO₂ in NiO/TiO₂ composite. The formation of NiO and NiO/TiO₂ was also verified by XRD analysis. The synthesized NiO and NiO/TiO₂ were used as photocatalysts for the degradation of Orange II (OII) dye. According to the degradation investigation, both NiO and NiO/TiO₂ composite degraded OII dye more efficiently when exposed to UV light. The results indicated that NiO degraded 93% and NiO/TiO₂ composites degraded approximately 96% of OII dye within 30 min. Both photocatalysts are highly sustainable and have significant OII dye degradation recyclability. Moreover, NiO and NiO/TiO₂ exhibited promising bioactivities (antioxidant activity of 80%) against the pathogenic bacteria Citrobacter and Providencia, which is comparable with the standard ascorbic acid (88%).     

Unusual enhancement of H2 evolution by Ru on TaON photocatalyst under visible light irradiation

H2 evolution on TaON photocatalyst under visible light irradiation (420 nm < or = lambda < or = 500 nm) in an aqueous methanol solution is found to be remarkably enhanced by adding Ru as a noble-metal co-catalyst.     

UV and visible light controllable depletion zone of ZnO-polyaniline p-n junction and its application in a photoresponsive sensor

In this communication, we report that the depletion zone thickness of the p-n junction between an n-type ZnO and a p-type polyaniline could be controlled by UV and visible light illumination. Based on this princile, photoresponsive sensors were constructed by combining polyaniline thin film and ZnO nanorods. Different from pure ZnO nanomaterials whose conductivity increases when they are exposed to UV illumination, the conductivity of the photoresponsive sensor studied in this communication decreased when the UV light was turned on. The surface modification of ZnO could switch the wavelength of the response light from UV to visible light.     

The coating of conducting copolymer on coordination polymer nanorod: A visible light active p-n heterojunction photocatalyst for H2 production

A visible light active p-n heterojunction photocatalyst was synthesized successfully through in-situ chemical oxidation copolymerization of aniline (ANI) and diphenylamine-4-sulfonate (DPAS) with the existence of coordination polymer nanorod (CPNR) under initiation of ammonium persulfate (APS). Compared with neat coordination polymer nanorod, the resulted p-n heterojunction photocatalyst exhibits higher H₂ generationrate under visible light irradiation. In this heterojunction photocatalyst, as a p-type semiconductor possessing suitable energy levels with coordination polymer nanorod, poly-(aniline-co-N-(4-sulfophenyl)-aniline) (PAPSA) forms p-n heterojunction with n-type coordination polymer nanorod, the inner electric field of p-n heterojunction accelerates the separation of electrons and holes, which enhances H₂ production performance. Furthermore, the influence of concentration ratio between DPAS and ANI on photocatalytic property of the p-n heterojunction photocatalyst was discussed and a reasonable condition to fabricate photocatalyst with high H₂ generationrate had been obtained. During photocatalytic water splitting H₂ generation, the p-n heterojunction photocatalyst exhibited outstanding stability.     

吸附法制备CdS/HKLBT复合催化材料及其可见光制氢活性

采用吸附法制备了CdS和层状物的复合光催化材料CdS/HKLBT(吸附),并采用X射线衍射(XRD)、紫外-可见漫反射(DRS)、透射电子显微镜(TEM)等技术对其进行了表征和分析。实验对比了吸附法制备的复合材料与离子交换法制备材料活性差异,考察了CdS负载量对复合物制氢活性的影响.结果表明,表面复合也能明显提高CdS的可见光制氢活性,当CdS复合量为15%(质量分数)时活性最高,达到532μmol/h,与离子交换法制备的光催化剂的产氢速率接近;而过多CdS的负载造成载流子迁移的障碍,从而不利于活性的提高.     

Mercury oxide as an efficient photocatalyst for degradation of rhodamine B dye under visible-light irradiation

In this work, a new visible-light-responsive photocatalyst, mercury oxide (HgO) was successfully developed. Its activity is significantly higher than that of the highly efficient photocatalyst, Ag₃PO₄ in degradation of rhodamine B (RhB) dye under irradiation of visible light. The HgO photocatalyst can be reused for at least three cycles without obvious loss of its activity in the degradation experiments. It was found that the RhB degradation rate is significantly influenced by the dye solution pH. The ultrahigh photocatalytic activity of HgO is attributed to its strong oxidization-ablility of the photogenerated holes, and high separation-possibility of the photogenerated carriers.     

Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are uncommon.Herein,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coor...     

Photocatalytic degradation of azo dyes catalyzed by Ag doped TiO2 photocatalyst

In this paper, photocatalytic degradation of commercial textile azo dyes catalyzed by titanium dioxide and modified titanium dioxide with Ag metal (1% w/w) in aqueous solution under irradiation with a 400 W high-pressure mercury lamp is reported. The effect of various parameters such as irradiation time of UV light, amount of photocatalyst, flow rate of oxygen, pH and temperature for the Ag-TiO₂ photocatalyst were investigated. Kinetic investigations of photodegradation indicated that reactions obey improved Langmuir-Hinshelwood model and pseudo-first-order law. The rate constant studies of photocatalytic degradation reactions for Ag-TiO₂ and TiO₂ photocatalysts indicated that in all cases the rate constant of the reaction for Ag-TiO₂ was higher than that of TiO₂.     

Water-mediated promotion of dye sensitization of TiO2 under visible light

Preadsorbed water along with surrounding bulk water significantly modulates the surface electronic structure of TiO(2), switches the adsorption mode of dyes, and promotes dye sensitization of TiO(2) under visible-light irradiation. This opens a door toward facile improvement in the efficiency of photodegradation of dyes and dye-sensitized solar cells under visible-light irradiation without any complicated and expensive surface modulation.     

Intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid under different water quality and light conditions

Oxidation of sulfite is an important process in wet flue gas desulfurization. Using highly purified water or distilled water as a reaction medium and a transparent or an opaque intermittent reaction apparatus, the intrinsic oxidation kinetics of sulfite catalyzed by peracetic acid was investigated under four different conditions. The reaction order of the reagents and the activation energy were obtained. The results indicate that water quality and light have no obvious effects on the reaction order and activation energy, but have an influence on the reaction rate constant. The mechanism of the intrinsic reaction is proposed. The results derived with this mechanism are in good agreement with the experimental results. Supported by the National Basic Research Program of China (Grant No. JK00020), the Doctor Research Fund from North China Electric Power University (Grant No. 200612008), and the National High Technology Research and Development Program of China (Grant No. 2007AA061703)