Synthesis of the Dy: SrMoO4 with High Photocatalytic Activity under Visible Light Irradiation

Dysprosium (Dy)‐doping SrMoO₄ (with different molar ratio of Dy/Sr = 0/100, 10/100, 15/100 and 20/100) have been synthesized by high temperature thermal decomposition of metal–organic salt in organic solvent with a high boiling point. Their structures, morphology, and optical properties were characterized by X‐ray diffraction (XRD), high‐resolution tuning electron microscopy ((HR)TEM), X‐ray photo‐electron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Using this method, the pure phase, nano‐size, and low band gap of SrMoO₄ sample are obtained. The results shows that the size of as‐synthesized SrMoO₄ nanoparticles was about 200 nm. The band gap of Dy‐doped SrMoO₄ ranges from 3.76–3.90 eV, and decreases with increasing Dy concentration. The photocatalytic performance of as‐syntheszied products were determined from the degradation of methylene blue (MB) by UV–vis light irradiation. The 15 mol%Dy‐doped SrMoO₄ sample shows the best performance for photocatalytic degradation of methyl blue of nearly 100% in 120 min under visible irradiation, which is higher than most of those reported before. The present work is meaningful for revealing the underlying mechanism in photocatalyst and improving the photocatalytic performance.     

Visible‐light‐driven self‐cleaning SERS substrate of silver nanoparticles and graphene oxide decorated nitrogen‐doped titania nanotube array

Graphene oxide (GO) and silver nanoparticles (Ag NPs) sequentially decorated nitrogen‐doped titania nanotube array (N‐TiO₂ NTA) had been designed as visible‐light‐driven self‐cleaning surface‐enhanced Raman scattering (SERS) substrate for a recyclable SERS detection application. N‐TiO₂ NTA was fabricated by anodic oxidation and then doping nitrogen treatment in ammonia atmosphere, acting as a visible‐light‐driven photocatalyst and supporting substrate. Ag/GO/N‐TiO₂ NTA was prepared by decorating GO monolayer through an impregnation process and then depositing Ag NPs through a polyol process on the surface of N‐TiO₂ NTA, acting as the collection of organic molecule and Raman enhancement. The SERS activity of Ag/GO/N‐TiO₂ NTA was evaluated using methyl blue as an organic probe molecule, revealing the analytical enhancement factor of 4.54 × 10⁴. Ag/GO/N‐TiO₂ NTA was applied as active SERS substrate to determine a low‐affinity organic pollutant of bisphenol A, revealing the detection limit of as low as 5 × 10^?7 m . Ag/GO/N‐TiO₂ NTA could also achieve self‐cleaning function for a recycling utilization through visible‐light‐driven photocatalytic degradation of the adsorbed organic molecules. Ag/GO/N‐TiO₂ NTA has been successfully reused for five times without an obvious decay in accuracy and sensitivity for organic molecule detection. The unique properties of this SERS substrate enable it to have a promising application for the sensitive and recyclable SERS detection of low‐affinity organic molecules. Copyright © 2016 John Wiley & Sons, Ltd.     

Optimizing adsorptive removal of malachite green and methyl orange dyes from simulated wastewater by Mn‐doped CuO‐Nanoparticles loaded on activated carbon using CCD‐RSM: Mechanism,regeneration, isotherm,kinetic, and thermodynamic studies

In the present work, Mn‐doped CuO‐NPs‐AC was prepared by a simple method, characterized using various techniques such as FESEM, EDX, XRD, PSD, and pH_pzc and finally used for the adsorption of malachite green (MG) and methyl orange (MO) in a number of single and binary solutions. A series of adsorption experiments were conducted to investigate and optimize the influence of various factors (such as different pH, concentration of MG and MO, adsorbent mass, and sonication time) on the simultaneous adsorption of MG and MO using response surface methodology. Under optimal conditions of pH 10, adsorbent dose of 0.02 g, MG concentration of 30 mg L^?1, MO concentration of 30 mg L^?1, and sonication time of 4.5 min at room temperature, the maximum predicted adsorption was observed to be 100.0%, for both MG and MO, showing that there is a favorable harmony between the experimental data and model predictions. The adsorption isotherm of MO and MG by Mn‐doped CuO‐NPs‐AC could be well clarified by the Langmuir model with maximum adsorption capacity of 320.69 mg g^?1 and 290.11 mg g^?1 in the single solution and 233.02 mg g^?1 and 205.53 mg g^?1 in the binary solution by 0.005 g of adsorbent mass for MG and MO, respectively. Kinetic studies also revealed that both MG and MO adsorption were better defined by the pseudo‐second order model for both solutions. In addition, the thermodynamic constant studies disclosed that the adsorption of MG and MO was likely to be influenced by a physisorption mechanism. Eventually, the reusability of the Mn‐doped CuO‐NPs‐AC after six times showed a reduction in the adsorption percentage of MG and MO.     

Enhanced visible‐light‐driven photocatalytic activity of F doped reduced graphene oxide ‐ Bi2WO6 photocatalyst

The reduced graphene oxide‐Bi₂WO₆ (rGO‐BWO) photocatalysts with the different R_F/O values (molar ratio of the F molar mass and the O's molar mass of Bi₂WO₆) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F^? ions had been successfully doped into rGO‐BWO samples. With the increasing of the R_F/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with R_F/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F^? ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition.     

无机离子对Ag_3PO_4可见光降解亚甲基蓝的影响

以亚甲基蓝(MB)为模拟废水污染物,Ag3PO4为光催化剂,固定污染物初始浓度、催化剂用量、光照强度和照射时间等,探讨不同浓度的无机阴、阳离子(NO-3、Cl-、SO2-4、Na+、Ca2+、Mg2+、Al 3+)对Ag3PO4光催化降解偶氮染料MB的影响.结果表明,Na+和NO-3对Ag3PO4光催化降解MB没有明显的影响;Cl-在一定程度上对MB的降解具有促进作用;SO2-4、Ca2+、Mg2+、Al3+在不同程度上抑制了该光催化反应的进行,且抑制顺序为SO2-4Ca2+Mg2+Al 3+.     

Nitrogen‐doped graphene‐cerium oxide (NG‐CeO2) photocatalyst for the photodegradation of methylene blue in waste water

This study shows a facile approach for the preparation of CeO₂ nanoparticles decorated with porous nitrogen‐doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen‐doped graphene‐cerium oxide (NG‐CeO₂) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE‐SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG‐CeO₂ have an average particle size of 20 nm. The as‐prepared NG‐CeO₂ nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO₂. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.     

Effect of Fe3O4‐doped sepiolite on the flammability and thermal degradation properties of epoxy composites

As‐received sepiolite/epoxy systems and Fe₃O₄‐doped sepiolite/epoxy systems were prepared, and the contents of sepiolite and Fe₃O₄‐doped sepiolite were kept as 2 and 4 wt%, respectively. Compared with sepiolite, the effect of Fe₃O₄‐doped sepiolite on the flame retardancy, combustion properties, thermal degradation, thermal degradation kinetics and thermomechanical properties of epoxy resin was investigated systematically by limiting oxygen index (LOI), cone calorimeter (Cone), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Some interesting results had been acquired. The addition of sepiolite decreased heat release rate, total smoke production and smoke production rate, and obviously improved LOI values of epoxy composites. Compared with sepiolite, the addition of Fe₃O₄‐doped sepiolite further reduced parameters mentioned above of epoxy composites, and further enhanced LOI values and char residues after cone test. There might be a synergistic effect between sepiolite and Fe₃O₄ on flame retardant epoxy composite. TGA results indicated that the addition of sepiolite had a slight effect on the thermal degradation of epoxy composites; however, the addition of Fe₃O₄‐doped sepiolite accelerated the thermal degradation of epoxy composites. DMA results showed that the addition of both sepiolite and Fe₃O₄‐doped sepiolite increased the glass transition temperature (T_g) of epoxy composite. The results obtained in this paper supplied an effective solution for developing excellent flame retardant properties of polymeric materials. Copyright © 2015 John Wiley & Sons, Ltd.     

Dual functional novel catalytic Cu1−xZrxFe2O4 (x=0, 0.5, 1) nanoparticles for synthesis of polysubstituted pyridines and sunlight‐driven degradation of methylene blue

The effect of varied zirconium content on the structural, morphological, magnetic, optical, thermal and catalytic properties of nanoparticles of the ferrite Cu_1 ? xZr_xFe₂O₄ (x = 0, 0.5, 1) was investigated. The mixed ferrite was synthesized by the auto‐combustion method using nitrates of respective metals and citric acid as a chelating agent. The as‐prepared nanoparticles showed dual benefits. They were employed as a heterogeneous catalyst for one‐pot synthesis of polysubstituted pyridine derivatives as well as for catalytic degradation of industrial waste dyes such as methylene blue (MB). The highlight of the research reported is the catalytic degradation of industrial waste (MB) with high efficiency in eluent of a wide range of pH (3–13). The proposed nanoparticles arguably offer certain great advantages that include: low cost, facile nature, anti‐leaching property, magnetic recoverability and recyclability. The characterization of the as‐synthesized nanoparticles was done using various techniques. The leaching study was carried out using inductively coupled plasma optical emission spectroscopy. The formation of organic products was confirmed using Fourier transform infrared and ¹H NMR spectroscopies and examination of degradation products of MB dye was carried out using mass spectrometry and UV–visible spectroscopy.     

Synthesis of iron‐based metal organic framework and its visible light‐driven photocatalytic degradation of dye pollutants

A novel metal–organic compound [Fe (ox)(phen)]_n (phen = 1,10‐Phennannthroline, ox = oxalate acid) has been hydrothermally synthesized and structurally characterized by X‐ray single‐crystal diffraction, X‐ray diffraction, IR, UV–vis diffuse reflectance spectroscopy and X‐ray photoelectron spectroscopy. The compound crystallized in monoclinic,space group P2₁ with a = 0.92289 (3) nm, b = 1.35719 (3) nm, c = 1.02012 (4) nm,β = 94.372 (2)°,V = 1.27402(8)nm³,Z = 2,and exhibited a 2D layer structure. The photocatalytic activities of the compound were evaluated by decomposing Rhodamine B (RhB) and methyl orange (MO) under the visible light irradiation. In addition, the mechanism of the photocatalytic properties were proposed during this process.     

Synthesis,structure and photocatalytic degradation of organic dyes of a copper(II) metal–organic framework (Cu–MOF) with a 4‐coordinated three‐dimensional CdSO4 topology

Metal–organic frameworks (MOFs) have attracted much interest in the fields of gas separation and storage, catalysis synthesis, nonlinear optics, sensors, luminescence, magnetism, photocatalysis gradation and crystal engineering because of their diverse properties and intriguing topologies. A Cu–MOF, namely poly[[(μ₂‐succinato‐κ²O:O′){μ₂‐tris[4‐(1,2,4‐triazol‐1‐yl)phenyl]amine‐κ²N:N′}copper(II)] dihydrate], {[Cu(C₄H₄O₄)(C₂₄H₁₈N₁₀)]·2H₂O}_n or {[Cu(suc)(ttpa)]·2H₂O}_n, (I), was synthesized by the hydrothermal method using tris[4‐(1,2,4‐triazol‐1‐yl)phenyl]amine (ttpa) and succinate (suc^2?), and characterized by IR, powder X‐ray diffraction (PXRD), luminescence, optical band gap and valence band X‐ray photoelectron spectroscopy (VB XPS). Cu–MOF (I) shows a twofold interpenetrating 4‐coordinated three‐dimensional CdSO₄ topology with point symbol {6⁵·8}. It presents good photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB) under visible‐light irradiation. A photocatalytic mechanism was proposed and confirmed.     

CuO nanoparticles supported on three‐dimensional nitrogen‐doped graphene as a promising catalyst for thermal decomposition of ammonium perchlorate

In the present work, CuO nanoparticles grown on three‐dimensional nitrogen‐doped graphene‐based frameworks (CuO@3D‐(N)GFs) were synthesized using a two‐step method. After the synthesis of three‐dimensional nitrogen‐doped graphene, CuO nanoparticles were deposited on it, by adding cupric acetate followed by thermal treatment. Different analysis methods were used to characterize the products. The as‐prepared nanocomposite was used as a promising catalyst for thermal decomposition of ammonium perchlorate (AP) as one of the most common oxidizer in composite propellants. Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) techniques were used to investigate the thermal decomposition of ammonium perchlorate. According to the DSC/TGA, high temperature decomposition of AP decreased to 111 °C in the presence of 4% CuO@3D‐(N)GFs and the total heat release (ΔH) from decomposition of AP increased to 1893 J g^?1 which is much more than 590 J g^?1 for pure AP.     

Synthesis of W‐doped TiO2 by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

A series of tungsten‐doped Titania photocatalysts were synthesized using a low‐temperature method. The effects of dopant concentration and annealing temperature on the phase transitions, crystallinity, electronic, optical, and photocatalytic properties of the resulting material were studied. The X‐ray patterns revealed that the doping delays the transition of anatase to rutile to a high temperature. A new phase W_yTi_1‐yO₂ appeared for 5.00 wt% W‐TiO₂ annealed at 900 °C. Raman and diffuse reflectance UV–Vis spectroscopy showed that band gap values decreased slightly up to 700 °C. X‐ray photoelectron spectroscopy showed that surface species viz. Ti³⁺, Ti⁴⁺, O^2?, oxygen‐vacancies, and adsorbed OH groups vary depending on the preparation conditions. The photocatalytic activity was evaluated via the degradation of methylene blue using LED white light. The degradation rate was affected by the percentage of dopants. The best photocatalytic activity was achieved with the sample labeled 5.00 wt% W‐TiO₂ annealed at 700 °C.     

Polyoxometalate encapsulated in metal‐organic gel as an efficient catalyst for visible‐light‐driven dye degradation applications

Contamination of industrial sewage by organic dye pollutants is one of the most common challenges to the daily life. Decontamination can be achieved by adsorption and photodegradation of the pollutants. Herein, an effective visible light‐driven photocatalyst of polyoxometalate encapsulated in metal–organic gel was presented. The resulting composite was named PMA@ MOG‐Cr [PMA= H₃PMo₁₂O₄₀, MOG= metal‐organic gel]. Photodegradation of dye pollutants with PMA@ MOG‐Cr were tested. The introduction of Phosphomolybdic Acid significantly enhanced the light‐absorption properties of MOG‐Cr. The PMA@MOG‐Cr showed an excellent photodegradation efficiency of MB, RhB and MO as high as 99% and 97% in 60 min and 91% in 120 min of visible‐light irradiation with only 10 mg photocatalyst, which was the highest among the tested samples MOG‐Cr, PMA@ MOG‐Cr and Degussa P‐25. The mechanism of the photodegradation of dye pollutants with H₂O₂ over PMA@MOG‐Cr under the visible light was further illustrated. The introduction of PMA promotes effective separation of electron–hole pair by trapping and transferring photogenerated electron. Thus, the two components act in synergy to result in much improved adsorption of certain common organic dyes as well as enhanced oxidative degradation. This work provides a new approach to design MOG encapsulated Polyoxometalate for visible light‐induced photodegradation of organic contaminants for the environmental remediation.     

Facilitating a high‐performance photocatalyst for Suzuki reaction: Palladium nanoparticles immobilized on reduced graphene oxide‐doped graphitic carbon nitride

We prepared a non‐covalently coupled hybrid of reduced graphene oxide (rGO)‐doped graphitic carbon nitride (g‐C₃N₄) by freezing‐assisted assembly and calcination. Fourier transform infrared, Raman and X‐ray photoelectron spectroscopies and transmission electron microscopy confirmed that rGO was incorporated into the bulk g‐C₃N₄, which was an ideal support for loading Pd nanoparticles. The Pd nanoparticles with an average size of 4.57 nm were uniformly dispersed on the rGO‐doped g‐C₃N₄ surface. The layered structure provided large contact area of g‐C₃N₄ with rGO, further accelerating the electron transfer rate and inhibiting electron–hole recombination. Consequently, compared with Pd/rGO/g‐C₃N₄ and Pd/g‐C₃N₄, the Pd/rGO‐doped g‐C₃N₄ showed a prominent catalytic activity for visible‐light‐driven photocatalytic Suzuki–Miyaura coupling at ambient temperature. The Pd/rGO‐doped g‐C₃N₄ exhibited very high stability after six consecutive cycles with minimal loss of catalytic activity.     

硼铈共掺杂纳米TiO2光催化降解三氯杀螨醇和菊酯类农药

采用溶胶-凝胶法在钛酸丁酯水解过程引入硼酸、硝酸铈,制备具有光催化活性的硼铈共掺杂纳米二氧化钛（TiO2）,经XRD、TEM、FT-IR、UV-Vis-DRS表征晶体结构,在日光灯照射下,光催化降解三氯杀螨醇、高氟氯氰菊酯、氟戊菊酯农药。结果表明：硼铈共掺杂的TiO2只有锐钛矿型,而纯的或掺铈的TiO2有含有锐钛矿型、金红石相和少量板钛矿型,UV-Vis-DRS测定结果表明硼铈共掺杂的TiO2禁带宽度变小,硼铈共掺杂的TiO2在可见光区吸光度高于掺杂铈和不掺杂的TiO2,在420nm~850nm有强的吸收;在同样光照下对三氯杀螨醇、高氟氯氰菊酯、氟戊菊酯的降解试验证明硼铈共掺杂纳米TiO2的光催化活性高于不掺杂或只掺杂铈的TiO2。     

Preparation of BiVO4/MIL‐125(Ti) composite with enhanced visible‐light photocatalytic activity for dye degradation

Because of their desired features, including very specific surface areas and designable framework architecture together with their possibility to be functionalized, Metal Framework (MOF) is a promising platform for supporting varied materials in respect of catalytic applications in water treatment. In this work, a novel visible‐light‐responsive photocatalyst that comprised BiVO₄ together with MIL‐125(Ti), was synthesized by a two‐step hydrothermal approach. The characterization of as‐obtained samples as performed by X‐ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscope, X‐ray photoelectron spectroscopy and ultraviolet‐visible diffuse reflection spectra. Rhodamine B was selected being a target for the evaluation of the photocatalytic function of as‐developed photocatalyst. The photocatalytic reaction parameters, for example, the content of BiVO₄ as well as initial concentration of Rhodamine B was researched. The composite photocatalyst possessing Bi:Ti molar ratio of 3:2 brought to light the fact that the greatest photocatalytic activity had the ability to degrade 92% of Rhodamine B in 180 min. In addition to that, the BiVO₄/MIL‐125(Ti) composite could keep its photocatalytic activity during the recycling test. The phenomenon of disintegration of the photo‐generated charges in the BiVO₄/MIL‐125(Ti) composite was brought to discussion as well.     

Facile one‐step synthesis of broken case‐like carbon‐doped g‐C3N4 for photocatalytic degradation of benzene

Herein, a novel broken case‐like carbon‐doped g‐C₃N₄ photocatalyst was obtained via a facile one‐pot pyrolysis and cost‐effective method using glyoxal‐modified melamine as a precursor. The obtained carbon/g‐C₃N₄ photocatalyst showed remarkable enhanced photocatalytic activity in the degradation of gaseous benzene compared with that of pristine g‐C₃N₄ under visible light. The pseudo‐first‐order rate constant for gaseous benzene degradation on carbon/g‐C₃N₄ was 0.186 hr^?1, 5.81 times as large as that of pristine g‐C₃N₄. Furthermore, a possible photocatalytic mechanism for the improved photocatalytic performance over carbon/g‐C₃N₄ nanocomposites was proposed.     

Facile fabrication of g‐C3N4/MIL‐53(Al) composite with enhanced photocatalytic activities under visible‐light irradiation

A novel visible‐light‐driven g‐C₃N₄/MIL‐53(Al) composite photocatalyst was successfully prepared using a facile stirring method at room temperature. The g‐C₃N₄/MIL‐53(Al) composites were characterized and their effects on the photocatalytic activities for rhodamine B degradation were investigated. The g‐C₃N₄(20 wt%)/MIL‐53(Al) photocatalyst displayed optimal photocatalytic degradation efficiency, which was about five times higher than the photocatalytic activity of pure g‐C₃N₄. The improved photocatalytic performance of the g‐C₃N₄/MIL‐53(Al) photocatalyst was predominantly attributed to the efficient separation of electron–hole pairs and the low charge‐transfer resistance. g‐C₃N₄/MIL‐53(Al) also exhibited excellent stability and reusability. A proposed mechanism for the enhanced photocatalytic activity is also discussed based on the experimental results. Copyright © 2015 John Wiley & Sons, Ltd.     

Determination of bifonazole and identification of its photocatalytic degradation products using UPLC‐MS/MS

The main goal of the presented work was to investigate the effect of ZnO or/and TiO₂ on the stability of bifonazole in solutions under UVA irradiation. To this end, a simple and reproducible UPLC method for the determination of bifonazole in the presence of its photocatalytic degradation products was developed. Linearity was studied in the range of 0.0046–0.15 mg mL⁻¹ with a determination coefficient of 0.9996. Bifonazole underwent a photocatalytic degradation process under the experimental conditions used. Comparative studies showed that combination of TiO₂/ZnO (1:1 w /w) was a more effective catalyst than TiO₂ or ZnO with a degradation rate of up to 67.57% after 24 h of irradiation. Further, kinetic analyses indicated that the photocatalytic degradation of bifonazole in the mixture of TiO₂/ZnO can be described by a pseudo‐first order reaction. Statistical comparison clearly indicated that the presence of TiO₂/ZnO also affected the stability of bifonazole from a cream preparation after 15 h of UVA exposure (p < 0.05). Ten photodegradation products of bifonazole were identified for the first time and their plausible fragmentation pathways, derived from MS/MS data, were proposed. The main pathway in the photocatalytic transformation of bifonazole in the presence of ZnO or/and TiO₂ involves hydroxylation of the methanetriyl group and/or adjacent phenyl rings and cleavage of the imidazole moiety.