Biosynthesis of copper nanoparticles supported on manganese dioxide nanoparticles using Centella asiatica L. leaf extract for the efficient catalytic reduction of organic dyes and nitroarenes

In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐sourced reducing agent,without stabilizers or surfactants.This synthetic process is environmentally‐friendly and avoids the use of toxic reducing agents.Phenolic hydroxyl groups in the leaf extract are believed to reduce Cu2+in solution to generate Cu NPs that are subsequently stabilized on the MnO2NP surfaces.The resulting Cu/MnO2nanocomposite was fully characterized using X‐ray diffraction,transmission electron microscopy,field emission scanning electron microscopy,energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy.This material was found to function as a highly active,efficient and recyclable heterogeneous catalyst for the reduction of Congo red,rhodamine B and methylene blue as well as nitro compounds such as2,4‐dinitrophenylhydrazine and4‐nitrophenol in the presence of NaBH4in aqueous media at ambient temperature.The high stability of the Cu/MnO2nanocomposite also allows the catalyst to be separated and reused several times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

THE STUDY OF PHOTOELECTROCHEHICAL CELLS BASED ON CHLOROPHYLL AND ORGANIC DYES

Tetraiodofluorescein(TIF)and safranine T(ST)had great effects on the photovoltaic parameters of the cells.The Voc of the cells was about 3-5 times higher than that of the cells without TIK and ST,Isc increased 1 to 2 orders of magnitude.The Voc and Isc could be increased greatly only when Voc and Isc of the cell with Pt as WE properly combined with the Voc and Isc produced by chla in the original cell.According to absorption spectra and output characters,the results were elucidated.

Enhancement of Two-photon Absorption by Ce^(3+) Sensitization in Organic Dyes

The two-photon absorption（TPA）and TPA-induced frequency upconversion emission properties of the dyes 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and the complex of 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and Ce（NO3）3 were experimentally studied.It was found that the TPA cross section for the dye sensitized by Ce3＋ is two factors larger than that of the dye without being sensitized.A three-level system model of the dye molecules was used to analyze the enhancement of TPA by the sensitizer Ce3＋,which indicated that the sensitizer results in the increase of the transition dipole moment from the one-photon allowed excited state（1Bu）to the two-photon allowed excited state（2Ag）.

Trace nitrogen-doped hierarchical porous biochar nanospheres:Waste corn roots derived superior adsorbents for high concentration single and mixed organic dyes removal

Seeking high performance adsorbents for highly efficient treatment of wastewater containing organic dyes has become increasingly imperative worldwide.Herein,with a specific surface area(SSA)of 2,745.4 m^(2)·g^(−1),trace N-doped porous biochar nanospheres(NPBs)are derived for the first time from affluent waste corn roots,via a hydrothermal conversion followed by a mild calcined activation by K2CO3(KC)in the presence of low virulent melamine.Melamine acts as N source and synergistic activator for significant promotion in SSA,pore volume,and surface defects.The obtained NPBs(CHC-0.5N-4KC-900)are confirmed as superior adsorbents for removal of organic dyes rhodamine B(RhB,qm=1,630.7 mg·g^(−1))and Congo red(CR,qm=1,766.2 mg·g^(−1))as well as their mixtures,within not only a low(<50 mg·L^(−1))but also a high(>50,esp.250–1500 mg·L^(−1))concentration range.The values for qm are far beyond commercially activated carbon(AC)as well as most reported biomass derived carbons,undoubtedly revealing the NPBs as great promising candidate adsorbents for disposal of real industrial wastewater.In addition,the adsorption of RhB is fitted by Langmuir,Freundlich,Temkin,and Dubinin–Radushkevich isotherm models.The kinetic analysis indicates that the adsorption before equilibrium conforms to the pseudo-second-order model,and the hydrogen bonding,electrostatic attraction,and esp.π–πinteraction have contributed to the superior adsorption performance of the NPBs.

Enhanced Photocatalytic Activity of TiO2 Nanofibers and Their Flexible Composite Films： Decomposition of Organic Dyes and Efficient H2 Generation from Ethanol-Water Mixtures

TiO2 nanofibers decorated with Pt and Pd nanoparticles have been synthesized and studied in various photocatalytic processes. Excellent photocatalytic behavior in the decomposition of organic dyes in water, degradation of organic stains on the surface of flexible freestanding cellulose/catalyst composite films and in generation of hydrogen from ethanol using both suspended and immobilized catalysts are demonstrated. The performance of the nanofiber-based TiO2 materials is competitive with and in some cases outperforms--their conventional nanoparticle-based counterparts. In all cases, Pd-decorated TiO2 nanoparticles and nanofibers proved to be more efficient than their Pt-based counterparts, which could be explained on the basis of the formation of nano-sized Schottky interfaces at the contacts between TiO2 and metal nanoparticles. The feasibility of forming cellulose/catalyst composites provides a novel way of utilizing photocatalyst materials in large-area coatings and freestanding films.

Sulfonated Hollow Covalent Organic Polymer： Highly-Selective Adsorption toward Cationic Organic Dyes over Anionic Ones in Aqueous Solution

A sulfonated hollow covalent organic polymer （sh-COP-P） was prepared by post sulfonation of hollow covalent organic polymer （h-COP-P） synthesized through poly-condensation of tetrabiphenylporphyrin （TBPP）. In comparison with h-COP-P, sh-COP-P exhibits significantly enhanced adsorp- tion capacity of organic cationic dyes in aqueous solutions accompanied with notably reduced adsorption capacity of anionic dyes. This gives sh-COP-P a satisfactory performance in selectively separating cationic organic dyes from anionic ones, mainly attributed to the electrostatic interaction between polymer backbone and the guest molecules.

One-pot hydrothermal synthesis of hierarchical porous manganese silicate microspheres as excellent Fenton-like catalysts for organic dyes degradation

Towards bottlenecks demonstrated by typical Fenton-like catalysts in advanced oxidation processes(AOPs)for wastewater treatment,novel hierarchical porousMn^(2+)Mn_(6)^(3+)SiO_(12)(Mn_(7)SiO_(12),MSO-12)microspheres(specific surface area:434.90 m^(2)·g^(-1),pore volume:0.78 cm^(3)·g^(-1))were rationally designed and achieved via a simple one-pot hydrothermal method(150℃ and 12.0 h)without any pre-prepared templates or organic solvents,by using abundant MnCl_(2)·4H_(2)O and Na_(2)SiO_(3)·9H_(2)O as the basic raw materials.The MSO-12 microspheres are confirmed as high-efficiency Fenton-like catalysts for degradation of organic dyes(methylene blue(MeB),Rhodamine B(RhB),and methyl blue(MB))in the presence of H_(2)O_(2),with impressively high specific consumption amount of MeB(R=12.35 mg·g^(-1)·min^(-1))and extremely low leaching of Mn(Mnloss%=0.27%).Simultaneously,the synergetic effect of adsorption and degradation on the superior removal of MeB is uncovered.The excellent recycling performances,especially the satisfactory removal of MeB from the actual water bodies(e.g.,tap water and river water),as well as potential applications for degradation of RhB and MB enable the MSO-12 microspheres as a novel promising competitive candidate Fenton-like catalyst.

2D-π-A Type Organic Dyes Based on N,N-Dimethylaryl Amine and Rhodamine-3-acetic Acid for Dye-sensitized Solar Cells

Three organic dyes XS17--19 based on N,N-dimethylaryl amine and rhodamine-3-acetic acid moieties are designed and synthesized. These dyes were applied into nanocrystalline TiOa dye-sensitized solar cells through standard operations, showing strong absorption bands at around 320--650 rim, and exhibiting broad IPCE responses. Cell based on XS17 gave a Jsc of 3.7 mA/cm2, an open circuit voltage of 550 mV, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 1.4%. The low overall conversion efficiency is due to the modest IPCE and Voc values, which mainly stem from the acceptor of rhodanine-3-acetic acid.

Amperometric Biosensors Sensitive to Organic Peroxides Based on Immobilization of Redox Organic Dyes and Horseradish Peroxidase in Polyester Ionomer Film

Simple and effective organic biosensors sensitive to organic peroxides such as 2 butanone per oxide and tertbutyl hydroperoxide are constructed by immobilizing a series of redox organic dyes and horseradish peroxidase in Eastman AQ polymer film. The organic dyes are methylene blue, methylene green, meldola blue, new methylene blue N and N methyl phenazine methosulphate. The biosensors display high sensitivity and fast response to tertbutyl hydroperoxide and 2 butanone peroxide because of high efficiency of electron transfer between immobilized horseradish peroxidase and the electrode via the redox organic dyes. The comparison of the biosensors employing different organic dyes is made in formal potential, linear range and response time.

Photocatalytic degradation of organic dyes with H_3PW_(12)O_(40)/TiO_2-SiO_2

H3PW12O40/TiO2-SiO2 was synthesized by impregnation method which significantly improved the catalytic activity under simulated natural light. The prop- erties of the samples were characterized by Fourier trans- form infrared spectra （FTIR）, X-ray powder diffraction pattern （XRD）, Scanning electron micrographs （SEM）, and Zeta potential. Degradation of methyl violet was used as a probe reaction to explore the influencing factors on the photodegradation reaction. The results show that the opti- mal conditions are as follows： initial concentration of methyl violet of 10 mg·L^-1, pH of 3.0, catalyst dosage of 2.9 g·L^-1, and light irradiation time of 2.5 h. Under these conditions, the degradation rate of methyl violet is 95.4 %. The reaction on photodegradation for methyl violet can be expressed as the first-order kinetic model, and the possible mechanism for the photocatalysis under simulated natural light is suggested. After used continuously for five times, the catalyst keeps the inherent photocatalytic activity for degradation of dyes. The photodegradation of methyl orange, methyl red, naphthol green B, and methylene blue was also tested, and the degradation rate of dyes can reach 81%-100%.

A sensing mechanism for the detection of carbon nanotubes using selective photoluminescent probes based on ionic complexes with organic dyes

The multifunctional properties of carbon nanotubes(CNTs)make them a powerful platform for unprecedented innovations in a variety of practical applications.As a result of the surging growth of nanotechnology,nanotubes present a potential problem as an environmental pollutant,and as such,an efficient method for their rapid detection must be established.Here,we propose a novel type of ionic sensor complex for detecting CNTs–an organic dye that responds sensitively and selectively to CNTs with a photoluminescent signal.The complexes are formed through Coulomb attractions between dye molecules with uncompensated charges and CNTs covered with an ionic surfactant in water.We demonstrate that the photoluminescent excitation of the dye can be transferred to the nanotubes,resulting in selective and strong amplification(up to a factor of 6)of the light emission from the excitonic levels of CNTs in the near-infrared spectral range,as experimentally observed via excitation-emission photoluminescence(PL)mapping.The chirality of the nanotubes and the type of ionic surfactant used to disperse the nanotubes both strongly affect the amplification;thus,the complexation provides sensing selectivity towards specific CNTs.Additionally,neither similar uncharged dyes nor CNTs covered with neutral surfactant form such complexes.As model organic molecules,we use a family of polymethine dyes with an easily tailorable molecular structure and,consequently,tunable absorbance and PL characteristics.This provides us with a versatile tool for the controllable photonic and electronic engineering of an efficient probe for CNT detection.

Separation of Organic Dyes from Water by Colloidal Gas Aphrons

Colloidal gas aphrons (CGAs) are micron sized gas bubbles produced by stirring surfactant solutions at high speed. A single CGA dispersed in water is composed of a gaseous inner core, surrounded by a double water soapy layer. CGAs have large interfacial area per unit volume and exhibit relatively high stability. These characteristics make CGAs very suitable in flotation systems. This paper studied the flotation of organic dyes from water using CGAs. The experimental results show that the flotation process may follow four mechanisms, i.e., ion coupling of the oppositely charged species of the surfactant forming the CGA and the organic dye, reactions between CGA and the organic dye, ion dye complex adsorbed on the surface of CGAs, and hydrophilic or hydrophobic characteristics of the organic dyes.

Synthesis of Three-Dimensional Hierarchical Flower-Like Mg–Al Layered Double Hydroxides with Excellent Adsorption Performance for Organic Anionic Dyes

In this work,a facile and effective strategy to prepare three-dimensional(3D)hierarchical flower-like Mg–Al layered double hydroxides(3D-LDH)was developed via a one-step double-drop coprecipitation method usingγ-Al 2O 3particles as a template.The characterization and experimental results showed that the calcined product,3D-LDO,features a large specific surface area of 204.2 m^(2)/g,abundant active sites,and excellent adsorption performance for Congo red(CR),methyl orange(MO),and methyl blue(MB).The maximum adsorption capacities of 3D-LDO for CR,MO,and MB were 1428.6,476.2,and 1666.7 mg/g,respectively;such performance is superior to that of most reported adsorbents.The adsorption mechanism of organic anionic dyes by 3D-LDO was extensively investigated and attributed to surface adsorption,the memory effect of 3D-LDO,and the unique 3D hierarchical flower-like structure of the adsorbent.Recycling performance tests revealed that3D-LDO has satisfactory reusability for the three organic anionic dyes.

Syntheses of Some Organic Fluorescent Dyes for Security Tickers

Five organic fluorescence dyes were synthesized by two- or three-step reactions. These synthetic methods have an advantage of the simple processes, low costs and high yields. The compositions of the five compounds are characterized by IR, 1H NMR, elemental analyses and fluorescence spectroscopies. The quantum yields of fluorescence were measured.

Synthesis of nano-MoS_2/bentonite composite and its application for removal of organic dye

A nano-MoS2/bentonite composite was synthesized by calcinating MoS3 deposited on bentonite in H2. The obtained composite was characterized using thermogravimetric analysis, X-ray diffractometer, scanning electron microscope and transmission electron microscope. The results show that nano-MoS2 particles are distributed on the surface of bentonite and form layered structures with layer distance of about 0.64 nm. The composite presents an excellent performance for the removal of methyl orange. Some operation conditions affect the removal efficiency of methyl orange, such as dosage of composite, initial concentration of methyl orange, temperature and pH value. However, light source does not influence the removal efficiency. The removal mechanism is attributed to the adsorption of methyl orange on the nano-MoS2/bentonite composite. The adsorption of methyl orange on the composite is in accordance with the pseudo-second-order kinetic model.

Photocatalytic Cr(Ⅵ) reduction and organic-pollutant degradation in a stable 2D coordination polymer

A new coordination polymer,Zn(bpy)L(BUC‐21),(H2L=cis‐1,3‐dibenzyl‐2‐imidazolidone‐4,5‐dicarboxylic acid,bpy=4,4′‐bipyridine),has been synthesized under hydrothermal conditions,and characterized by single‐crystal X‐ray analysis,Fourier transform infrared spectroscopy,thermogravimetric analyses,CNH elemental analysis and UV‐Vis diffuse reflectance spectroscopy.BUC‐21exhibited an excellent performance for photocatalytic Cr(VI)reduction with a conversion efficiency of96%,better than that of commercial P25(39%),under UV light irradiation for30min.BUC‐21could also be used to conduct photocatalytic degradation of organic dyes including methylene blue,rhodamine B,methyl orange and reactive red X‐3B.Also,the photocatalytic activity of BUC‐21remained high across a wide pH range from2.0to12.0.It is interesting to note,however,that BUC‐21was unable to achieve simultaneous reduction of Cr(VI)and degradation of an organic pollutant in a mixed matrix,which can be attributed to the competition between Cr(VI)and the organic dyes for access to the photo‐excited electrons.

Study on Photocatalytic Degradation of Organic Dye by Titanium Dioxide Nanotube Array

Titanium based titanium dioxide （TiO2） nanotube arrays were prepared by electrochemical oxidation method, their microstructures were characterized, and the effects of sintering temperature and initial dye concentration and pH value on degradation performance of TiO2 nanotubc arrays wcrc investigated with methyl orange as a degradation object. The results showed that TiO2 nanotube arrays prepared by sintering at 500 ℃ exhibited good morphology and the highest photocata- lyric degradation efficiency; the degradation efficiency of the TiO2 nano material （500 ℃ ） to high concentration dye was higher than that to low concentration dye; the TiO2 nanotube array （500 ℃ ） exhibited higher degradation efficiency on dye solution at the pH of 3 than on that at the pH of 5.77 ; and the degradation efficien- cy of the TiO2 nanotube array （500 ℃） to 10 mg/L methyl orange solution （pH =3） reached 85.2%.

Photovoltaic Performance of Triphenylamine Dyes-sensitized Solar Cells Employing Cobalt Redox Shuttle and Influence of π-conjugated Spacers

Developing photosensitizers suitable for the cobalt electrolyte and understanding the structure-property relationship of organic dyes is warranted for the dye-sensitized solar cells （DSSCs）. The DSSCs incorporating tris（1,10-phenanthroline）eobalt（Ⅱ/Ⅲ）-based redox elec- trolyte and four synthesized organic dyes as photosensitizers are described. The photovoltaic performance of these dyes-sensitized solar cells employing the cobalt redox shuttle and the influences of the w-conjugated spacers of organic dyes upon the photovoltage and photocur- rent of mesoscopic titania solar cells are investigated. It is found that organic dyes with thiophene derivates as linkers are suitable for DSSCs employing cobalt electrolytes. DSSCs sensitized with the as-synthesized dyes in combination with the cobalt redox shuttle yield an overall power conversion efficiency of 6.1% under 100 mW/cm2 AM1.5 G illumination.

Irradiation Effect on Second Harmonic Generation of Dyes Doped KDP Crystals

Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet （UV） light, where the defects are closely related to the optical properties. But heavy ion beam irradiation effects have rarely been studied. The structural, optical, and non-linear optical properties of the doped crystals were analyzed with the characterization studies, such as powder XRD, UV-Visible and second harmonic generation （SHG） measurements, respectively. The results for doped KDP crystal were compared with the results of the pure KDP crystals. The experiment results showed that Li^3＋ irradiation leads to the development of a well-defined surface H peak in dye doped KDP crystals. The stability of KDP single crystal was improved by doping organic dyes. The nano-islands of dye in KDP were likely to be dissolved and enhance the non-linear optical properties of these materials.

Enhancement of electroluminescent properties of organic optoelectronic integrated device by doping phosphorescent dye

Organic optoelectronic integrated devices（OIDs） with ultraviolet（UV） photodetectivity and different color emitting were constructed by using a thermally activated delayed fluorescence（TADF） material 4, 5-bis（carbazol-9-yl）-1, 2-dicyanobenzene（2 CzPN） as host. The OIDs doping with typical red phosphorescent dye [tris（1-phenylisoquinoline）iridium（Ⅲ）, Ir（piq）3], orange phosphorescent dye {bis[2-（4-tertbutylphenyl）benzothiazolato-N,C-（2＇）]iridium（acetylacetonate）,（tbt）2 Ir（acac）}, and blue phosphorescent dye [bis（2, 4-di-fluorophenylpyridinato）-tetrakis（1-pyrazolyl）borate iridium（Ⅲ）, FIr6] were investigated and compared. The（tbt）2 Ir（acac）-doped orange device showed better performance than those of red and blue devices, which was ascribed to more effective energy transfer. Meanwhile, at a low dopant concentration of 3 wt.%, the（tbt）2 Ir（acac）-doped OIDs showed the maximum luminance, current efficiency, power efficiency of 70786 cd/m^2, 39.55 cd/A, and 23.92 lm/W, respectively, and a decent detectivity of 1.07 × 10^11 Jones at a bias of -2 V under the UV-350 nm illumination. This work may arouse widespread interest in constructing high efficiency and luminance OIDs based on doping phosphorescent dye.