Degradation Of RhB Dye Research Articles

可见光响应型纳米AgCl凸多面体制备及光催化性能研究

本文采用一种简单的高温溶剂方法合成了新颖的凸多面体状AgCl半导体纳米材料。通过X射线衍射仪，扫描电子显微镜，漫反射光谱和紫外–可见分光光度计对材料的微观结构和光催化性能进行了表征。结果显示，所得到的凸多面体氯化银纳米材料在可见光区间显示了非常好的吸收，并在降解罗丹明B染料的过程中显示出高效的光催化活性。此外，我们对所制得的AgCl凸多面体的光催化稳定性也进行了探讨。 Novel convex polyhedra-like AgCl nanoarchitectures were synthesized via a facile refluxing method in the polyoldiethylene glycol (DEG). The microstructure and photocatalytic properties of the prepared materials were characterized by X-ray diffraction, scanning electron microscope, diffuse reflectance spectroscopy and UV-visible spectrophotometry. Results show that the as-obtained AgCl nano-polyhedra could effectively increase the absorption of the photocatalysts from UV-light to visible light and show an obvious efficient photocatalytic activity for degradation of RhB dye. Besides, the stability of the product in organic dye photodegradation process was also investigated.

In situ Oxidation and Self-Assembly Synthesis of Dumbbell-like α-Fe2O3/Ag/AgX (X = Cl, Br, I) Heterostructures with Enhanced Photocatalytic Properties

In this work, the novel dumbbell-like α-Fe2O3/Ag/AgX (X = Cl, Br, I) heterostructures were successfully synthesized via an in situ oxidation reaction and self-assembly process by using the α-Fe2O3/Ag core–shell nanoparticles (NPs). The as-obtained dumbbell-like α-Fe2O3/Ag/AgX heterostructure contains an individual spindle-like α-Fe2O3 nanoparticle and a single near-spherical Ag/AgX nanoparticle. The morphology, microstructure, component and optical property of as-synthesized α-Fe2O3/Ag/AgX heterostructures were characterized by various analytical techniques. The great changing of morphology and component in such synthesis route make great effect on the final photocatalytic performance. The dumbbell-like α-Fe2O3/Ag/AgX heterostructures exhibit excellent photocatalytic activity for the degradation of RhB dye under simulated sunlight irradiation. In particular, the α-Fe2O3/Ag/AgCl can completely degrade RhB molecules within only 20 min under simulated sunlight irradiation, which is superior to the pure α-Fe2...

Photocatalytic efficiency of bismuth oxyhalide (Br, Cl and I) nanoplates for RhB dye degradation under LED irradiation

BiOX (X=Br, Cl and I) nanoplate photocatalysts were synthesized by hydrothermal method. The photocatalytic activity of the synthesized catalysts was evaluated for RhB dye degradation under four types of light emitting diodes (LEDs) irradiation possesses different wavelength. 100% RhB dye degradation was achieved for BiOCl and BiOBr catalysts within 120 and 240min under UVLED irradiation. Whereas BiOI catalyst owns 83.4% degradation under red LED (RLED) irradiation at the end of 240min. Our study reveals that BiOI photocatalyst could be effective for RhB dye degradation under cheaper RLED irradiation rather than UVLED.

Decolorization of RhB dye by manganese oxides: effect of crystal type and solution pH.

BackgroundOrganic dye pollution in water has become a major source of environmental pollution. Mn(III/IV) oxides have attracted a great deal of attention to remove organic dye pollutants due to their unique structures and physicochemical properties. Numerous studies have reported the removal of dye by various Mn(III/IV) oxides through catalytic degradation and adsorption. The crystalline structures of manganese oxides and solution pH may exert substantial impact on the removal of dyes. However, few studies have focused on the oxidative degradation of RhB dye using Mn(III/IV) oxides with different crystal structures during a spontaneous reaction. In the present study, three manganese oxides with different crystal type (α-MnO2, β-MnO2, and δ-MnO2) were prepared by refluxing process to decolorize RhB dye in various pH solutions.ResultsThe results showed that the decolorization efficiencies of RhB for the three manganese oxides all increase with decrease solution pH. α-MnO2 exhibited highest activity and could efficiently degrade RhB at pH 2–6. The degradation of RhB by β-MnO2 and δ-MnO2 could be observed at pH 2–3, and only little adsorption RhB on manganese oxides could be found at pH 4–6. The UPLC/MS analysis suggests that the decolorization of RhB by manganese oxides consists of three main stages: (1) cleavage of the ethyl groups from RhB molecular to form Rh; (2) further destruction of –COOH and –CNH2 from Rh to form the small molecular substances; (3) mineralization of the small molecular substances into CO2, H2O, NO3− and NH4+.ConclusionsOverall, these results indicate that α-MnO2 may be envisaged as efficient oxidants for the treatment of organic dye-containing wastewater under acid conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12932-015-0024-2) contains supplementary material, which is available to authorized users.

Study on photocatalytic activity of ZnO nanodisks for the degradation of Rhodamine B dye

Highly dense zinc oxide (ZnO) nanodisks (ZnO-NDs) were synthesized through the low temperature chemical method with zinc nitrate hexahydrate as raw materials, and applied as photocatalyst for the photocatalytic degradation of Rhodamine B (RhB) dye. The morphological results revealed that the synthesized materials possessed disks like morphology with the average size of ~200nm. In addition, the synthesized ZnO-NDs exhibited the good optical and structural properties with band gap of ~3.21eV. The catalytic activity of the synthesized ZnO-NDs was examined by performing the photocatalytic degradation of RhB dye under UV-light illumination. A rapid RhB-dye degradation was recorded with the high degradation rate ~90% in ~90min over the surface of ZnO-NDs.

One-pot hydrothermal synthesis of a novel BiPO4/BiOBr composite with enhanced visible light photocatalytic activities

The BiPO4/BiOBr composites were successfully fabricated by a facile one-step hydrothermal method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and photocurrent (PC) measurements were employed to characterize the crystal structures, morphologies, optical properties, recombination of photo-generated electron–hole pairs, and electron–hole separation effect of the photocatalysts. BiPO4/BiOBr composites exhibited much higher photocatalytic activity for the degradation of RhB and MO dye than single BiOBr and BiPO4 under visible light and simulated sunlight irradiation, respectively. The results of PL and PC measurements demonstrated that the large enhancement of photocatalytic activity could be mainly ascribed to the surface junction of BiPO4/BiOBr composite which can effectively improve electron–hole separation speed during photocatalytic process.

Synthesis of BiOBr-PVP hybrids with enhanced adsorption-photocatalytic properties

We synthesized BiOBr-PVP hybrids by a simple solvothermal process, and investigated the adsorption and photocatalytic properties. Due to the presence of PVP, the thickness of the BiOBr nanosheets in BiOBr-PVP hybrids can be greatly reduced, which increased the percentage of highly reactive (001) facets exposed. And PVP was found to be adsorbed on the surface of BiOBr nanosheets by a strong donor–acceptor interactions via CO bonds, which lead to an enhanced zeta potential and stronger adsorption capacity of cationic RhB molecules on the surface of BiOBr-PVP hybrids. And due to the synergistic effects of both high percentage of reactive (001) crystal facets and strong adsorption capacity, BiOBr-PVP hybrids exhibit excellent activities and stabilities on RhB dye degradation, which could be potentially used for practical waste water treatments.

Fabrication of sulfur-doped g-C3N4/Au/CdS Z-scheme photocatalyst to improve the photocatalytic performance under visible light

Au and CdS nanoparticles were firstly deposited on the surface of g-CNS by two-step self-assembly process to afford sandwich-structured Z-scheme g-CNS/Au/CdS photocatalyst. The photocatalytic reduction of water to hydrogen was highly improved in lactic acid scavenger solution using the as-prepared g-CNS/Au/CdS than using g-CNS/CdS in the presence of visible light, and the photocatalytic degradation of RhB dye was also improved. According to the photoluminescence spectra and excited state electron radioactive decay lifetime, when Au was paired between g-CNS and CdS, based on the Z-scheme charge-carrier transfer mechanism, the redox ability of the photogenerated holes and electrons was enhanced, followed by the increased lifetime of the photoelectrons. Therefore, the photocatalytic ability of the g-CNS/Au/CdS composite was significantly improved.

Microwave‐Solvothermal Synthesis of Nanostructured BiOBr with Excellent Visible‐Light Photocatalytic Properties

Novel BiOBr hierarchical microspheres have been successfully prepared via a facile microwave‐assisted solvothermal route and used for visible‐light photocatalytic degradation of RhB. The phase and morphology of the products were characterized by powder X‐ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), BET, and UV‐vis diffuse reflectance spectra. The SEM observations displayed that BiOBr flower‐like nanostructure assembled from nanosheets. The BiOBr flower‐like nanostructure, with a narrow band gap (2.63 eV), shows excellent photocatalytic activity in the degradation of RhB dye under visible‐light, much higher than those of BiOBr nanosheet and P25 photocatalysts.

Controllable synthesis of uniform BiOF nanosheets and their improved photocatalytic activity by an exposed high-energy (002) facet and internal electric field

Uniform BiOF nanosheets show an improved photocatalytic activity for the degradation of RhB dye.

Photoluminescence, photocatalysis and Judd–Ofelt analysis of Eu3+-activated layered BiOCl phosphors

Crystal structure of tetragonal BiOCl, field emission scanning electron micrographs, CIE chromaticity diagram and percentage of RhB dye degradation of Bi1−xEuxOCl.

Preparation, characterization, and enhanced visible-light photocatalytic activity of AgI/Bi2WO6 composite

In this study, a series of AgI/Bi2WO6 heterojunction photocatalysts were synthesized with deposition–precipitation method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), UV–vis diffuse reflectance spectroscopy (DRS). The photocatalysts exhibited enhanced photocatalytic activity on the RhB dye degradation under visible-light irradiation. The 58.5% AgI/Bi2WO6 sample was observed to have the highest photocatalytic degradation efficiency. Based on the calculated energy band positions, the mechanism of enhanced photocatalytic activity was discussed.

SiO2/carbon nitride composite materials: The role of surfaces for enhanced photocatalysis

The effect of SiO2 nanoparticles on carbon nitride (C3N4) photoactivity performance is described. The composite SiO2–C3N4 materials exhibit a higher activity in the photo degradation of RhB dye. A detailed analysis of the chemical and optical properties of the composite C3N4 materials shows that the photo activity increases with higher SiO2 concentration. We found out that the presence of SiO2 nanoparticles strongly affects the fluorescence intensity of the matrix and life time by the creation of new energy states for charge transfer within the C3N4. Furthermore, the use of SiO2 in the synthesis of C3N4 leads to new morphology with higher surface area which results in another, secondary improvement of C3N4 photoactivity. The effect of different surfaces within C3N4 on its chemical and electronic properties is discussed and a tentative mechanism is proposed. The utilization of SiO2 nanoparticles improves both photophysical and chemical properties of C3N4 and opens new possibilities for further enhancement of C3N4 catalytic properties by the formation of composites with many other materials.

Ligand-Free One-Step Synthesis of {001} Faceted Semiconducting BiOCl Single Crystals and Their Photocatalytic Activity

Herein, we report one-step ligand-free hydrothermal synthesis of predominantly {001}-faceted micron-sized single crystals of bismuth oxychloride (BiOCl). The structural chlorine is obtained by in situ generation of chloride ions. From Raman spectra, we could resolve the Eg transition. Photocatalytic activity of as-synthesized crystals showed 78% degradation of RhB dye under a xenon source after 120 min of exposure.

Controllable growth of BiOCl film with high percentage of exposed {0 0 1} facets

Bismuth oxychloride (BiOCl) granular and flake-like films with specific {001} crystal facets are synthesized by a facile hydrolysis route. The percentage of reactive {001} facets is up to 97.36% in granular film and 91.69% in flake-like film, respectively. It is found that the synthesized granular film is composed by the nano grains with average size around 5–10nm, but the flake-like film contains the flakes originated from the large nano crystals. The percentage of the {001} reactive facets and morphology of the BiOCl film can be tuned by adjusting the concentration or the pH value of the solution during the synthesis process, companied with the appearance of the (101), (102), and (110) facets. The formation mechanism of {001}-preferential orientation has been rationally explained in terms of crystal growth habit and dynamics. Photocatalytic degradation of RhB dye has been observed under UV light, representing that the flake-like film with {001} facets preferred orientation exhibits excellent photoactivity.

Photocatalytic Activities under UV Light of Ball-Milled TiO<sub>2</sub> Photocatalysts

Anatase TiO2powders used as photocatalysts were prepared by ball milling process at various milling time and annealed in nitrogen atmosphereat different temperatures. Commercial TiO2powders were ball-milled with ethanol at room temperature. After ball milling process, the samples were annealed in nitrogen atmosphere. The particle sizes and surface area of milled powders were measured by particle analyzer and Brunauer Emmet Teller method(BET). Effect of milling time and annealing temperature on structural properties of TiO2powders was investigated by X-ray diffraction(XRD) and scanning electron microscope(SEM). The degradation of aquous RhB dye by ball-milled TiO2powder photocatalyst was investigated under UV light irradiation. Comparing to P-25, TiO2powder prepared via ball milling process at 24 hr demonstrated significant enhancement in its photocatalytic activity under UV light due to the increasing active surface area after ball milling process.

Low-temperature synthesis of α-Fe2O3 hexagonal nanoparticles for environmental remediation and smart sensor applications

This work demonstrates the successful synthesis and characterizations of α-Fe2O3 hexagonal nanoparticles and their effective utilization for the degradation of hazardous Rhodamine B (RhB) dye and smart chemical sensor applications. The as-synthesized materials were characterized by various analytical techniques which revealed that the prepared nanoparticles are well-crystalline, possessing hexagonal shape, grown in high-density and well matched with the rhombohedral α-Fe2O3 structures. The as-synthesized α-Fe2O3 nanoparticles were used as efficient photocatalyst for the photocatalytic degradation of RhB-dye under light illumination which showed substantial degradation (~79%) of RhB-dye in 140 min. The considerable photo-degradation of RhB-dye attributed to the unique morphology of the synthesized α-Fe2O3 nanoparticles which might import the effective electron/hole separation and generate the large number of oxy-radicals. Moreover, the synthesized α-Fe2O3 nanoparticles were utilized as efficient electron mediators for the fabrication of 4-nitrophenol chemical sensor in aqueous media. The fabricated chemical sensor exhibited a high-sensitivity of ~367.6 µA (mol L(-1))(-1) cm(-2) and an experimental detection limit of ~1.56×10(-3) mol L(-1) in a short response time of ~10.0 s with linearity in the range of 1.56×10(-3)-12.5×10(-3) mol L(-1) and correlation coefficient (R) of ~0.99963. These investigations demonstrated that the simply synthesized α-Fe2O3 nanoparticles can effectively be used as efficient photocatalyst for the photocatalytic degradation of organic dyes and effective electron mediators for the fabrication of highly sensitive chemical sensors in aqueous medium.

Electrospinning direct preparation of SnO2/Fe2O3 heterojunction nanotubes as an efficient visible-light photocatalyst

Abstract Herein SnO2/Fe2O3 heterojunction nanotubes are prepared by a facile electrospinning technique. The heterojunction nanotubes with a diameter of about 200 nm uniformly distribute SnO2 and Fe2O3 nanocrystals and present the obvious interfaces between them, which form perfect SnO2/Fe2O3 nano-heterojunctions. A possible mechanism based on self-polymer-templates is proposed to explain the formation of SnO2/Fe2O3 heterojunction nanotubes. The heterojunction nanotubes show high photocatalytic activity for the degradation of RhB dye under visible light irradiation. The prepared SnO2/Fe2O3 heterojunction nanotubes can also be applied to other fields such as sensor, lithium-ion batteries.

Synthesis and characterization of cage-like core–shell structured TiO2 hollow microspheres

Cage-like core–shell structured TiO2 hollow microspheres have been fabricated by a simple procedure consisting of solvothermal synthesis and post-synthesis calcination. The structure and morphology were investigated by XRD, SEM, UV, and EDS. XRD and EDS studies indicated that the as-prepared products were well-crystallized anatase phase of TiO2. SEM images showed that the TiO2 samples were of cage-like hollow structures with a diameter of about 1 to 2μm. The mean diameter of the cores of those spheres is about 400nm. UV–vis spectrum reveals that the band gap energy of the cage-like core–shell structured TiO2 hollow microspheres were about 3.375eV. The as-prepared TiO2 samples showed excellent photocatalytic activity, which was evaluated by the degradation of RhB dye under ultraviolet light irradiation.

PEGME-bonded SnO2 quantum dots for excellent photocatalytic activity

The ultrafine SnO2 quantum dots (QDs) modified with poly(ethylene glycol methyl ether) (PEGME) (PEGME–SnO2 QDs) were synthesized via hydrothermal method. X-ray diffraction and high-resolution transmission electron microscopy were employed to illustrate that the PEGME–SnO2 QDs are uniform, monodispersed and about 4 nm in diameter. Then infrared spectrum and thermogravimetric analysis were used to prove that PEGME groups are bound tightly to SnO2 surfaces. The as-synthesized PEGME–SnO2 QDs excellently achieved photocatalytic degradation to Rhodamine B dye (RhB). The photon efficiency of the PEGME–SnO2 QDs catalyst and corresponding RhB dye degradation rate constant could reach 0.0058% and 9.98 × 10−2 min−1, respectively. This outstanding photocatalytic performance could be attributed to not only large surface-to-volume ratio and high crystallinity of the ultrafine and monodispersed QDs, but also good hydrophilicity and conductivity of the PEGME surface modifier. Remarkably, such PEGME–SnO2 QDs with outstanding photocatalytic efficiency and stable recyclability are promising to be applied to environmental purification.