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In this work, seven organic dyes were designed (M2–M7) to have the D-π1-Ai-π2-A structure from the reference dye M1, which has the D-π1-π2-A structure. By inserting different auxiliary acceptors Ai (i = 1–7) between the π1 and π2 onto the reference dye M1, we obtained the designed dyes to study their photovoltaic properties for use in DSSC devices. The geometrical structures, absorption spectrum properties, nonlinear optical properties (NLOs), energy levels, frontier molecular orbitals, and some photovoltaic parameters were theoretically investigated using density function theory (DFT) and time-dependent DFT (TD-DFT) methods, with the aim of improving the DSSC performance of the designed dyes. The theoretical results reveal that the designed dyes would be used as potential sensitizers in DSSCs due to their very small energy gaps, broad absorption spectra, higher NLO properties, lower reorganization energy (λtot), lower regeneration driving force (ΔGreg), longer excited lifetime (τ), higher vertical dipole moment (µnormal), reasonable electron injection driving force (∆Ginj), and equally reasonable light-harvesting efficiency (LHE) compared to the reference dye M1. Furthermore, the designed dyes (M2–M8) have better charge transferability, the highest stabilization energy, and the highest ability of electron-donating and electron-accepting, resulting in a high short-circuit current and better power conversion energy (PCE) compared to reference dye M1. These results show that the introduction of different auxiliary acceptors Ai can most effectively improve the photovoltaic performance of our system. [ABSTRACT FROM AUTHOR]

ZnO/carbon composites were prepared via hydrothermal method and carbonization using zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and glucose (C6H12O6) as zinc and carbon source, and ammonia as precipitation agent. The effects of glucose addition amount on the morphology and structure of ZnO/carbon composites were discussed. The chemical composition, morphology and structures of ZnO/carbon composites were characterized by XRD, FESEM, TG and Raman spectroscopy. The flower-like ZnO/carbon nanoparticle composites were obtained after carbonization at 600 °C for 2 h. The carbon content in ZnO/carbon composites increased with the increase of glucose, and the carbon content reached 28.8% when the glucose was 1.0 g. As the carbon content increases, carbon nanoparticles change from irregular particles to spherical particles, while the degree of graphitization of carbon in ZnO/carbon composites has not significant change. The photocatalytic performances of ZnO/carbon composites were studied by degradation of organic dye [rhodamine B (RhB) and methylene blue (MB)] under UV light irradiation, and the maximum degradation rate of RhB and MB reached 93.3% and 97.2%, respectively. [ABSTRACT FROM AUTHOR]

Dye-contaminated water from industry is hazardous to human and aquatic lives. Membrane technology is considered a viable approach to resolve the issue. Herein, copper oxide nanoparticles (CuO NPs) embedded in porous chitosan membranes have been prepared using a solution-casting approach with sodium tripolyphosphate as a crosslinker and polyethylene glycol as a porogen. The prepared membranes have been characterized by physicochemical, mechanical and photocatalytic properties. FTIR results indicate some hydrogen bonding across CuO NPs and the chitosan matrix. XRD and TGA analyses reveal that the membranes are thermally stable and somehow crystalline. SEM examination indicates that the membrane surfaces express porous/roughened texture. The contact angle measurement indicates that the pure chitosan and CuO NPs-embedded membranes are hydrophobic, whereas PEG-leached porous chitosan membranes express hydrophilicity. CuO NPs reinforcement has significantly improved the tensile strength, whereas the elongation at break decreased. The CuO NPs incorporated in chitosan membranes exhibit exceptional photocatalytic activities against methyl orange and methylene blue dyes for their effective removal from aqueous media. [ABSTRACT FROM AUTHOR]

This study reports the synthesis of a new composite material, polyaniline cobalt chloride (PAni)–(CoCl2), in powder form via a chemical method at room temperature, with varying weight percentages of the alkyl salt CoCl2 (5, 10, 20, and 40 wt%). The goal of this research is to enhance the physicochemical, magnetic, and electrical properties of the material. Cyclic voltammetry experiments confirmed the electrochemical activity of the PAni-CoCl2 electrode. The PAni-5% CoCl2 composite showed better results in electrochemical impedance spectroscopy (EIS) measurements than the PAni-10% CoCl2 and PAni-20% CoCl2 composites. Magnetization, X-ray diffraction (XRD), UV-vis, and Fourier transform infrared (FTIR) spectroscopy revealed a strong interaction between Co2+ and PAni chains, confirming the formation of a PAni/CoCl2 nanocomposite. The ferromagnetic polyaniline-cobalt chloride composite was used as an absorbent in environmental applications such as the removal of an organic dye, which in our study is methylene blue. [ABSTRACT FROM AUTHOR]

Anisotropic properties of aspherical nanoparticles make it possible to significantly expand their spectral-optical applications associated with local field effects. The plasmon resonance characteristics of such particles have additional features that conductive nanoglobules do not possess. The results of synthesis and morphological analysis of ellipsoidal hematite nanoparticles coated with a gold shell and spherical magnetite nanoparticles by atomic force microscopy are presented. The absorption spectra of aqueous solutions of such nanoparticles, as well as conductive nanoparticles with chain molecules adsorbed on them, are obtained. Based on the methods of dynamic light scattering, histograms of particle size distribution are constructed. The influence of spheroidal magnetic nanoparticles coated with a gold shell on the luminescence intensity of molecules of an organic dye (fluorescein) and poly[2-methoxy-5(2'-ethylhexyloxy)-1,4-phenylenevinylene] is studied. An increase in the luminescence intensity of both types of luminophors at certain concentrations of metallized spheroidal nanoparticles is detected. A mathematical model of radiative and nonradiative processes in the studied colloidal system is presented, as well as the results of calculations of spectral and velocity characteristics based on well-known applied FDTD packages. Characteristic graphs are constructed for the spectral density of the number of photons emitted at a certain frequency of the combined system "molecule–nanoparticle" for various positions of the nanoparticle relative to the molecule and two characteristic directions of the transition dipole moment vector. The relationship between the frequencies of two plasmon resonances and the eccentricity of the spheroid revealed in the model is clearly manifested in the obtained spectral curves. The closer the spheroid eccentricity to 0, the smaller the frequency interval between two spaced plasmon resonance peaks, which merge into a single spectral band at zero eccentricity. The results obtained can be used in the development and modification of sensors with an adjustable conformational structure of macrochains, such as luminescent optical testers for the concentration of molecular oxygen (including singlet oxygen) and chemical sensors based on the effects of surface plasmon resonance and surface-enhanced Raman scattering. [ABSTRACT FROM AUTHOR]

Here, the zinc sulfide–copper sulfide (ZnS–CuS) nanocomposites have been synthesized using immersing thin layers of ZnS in 0.5 (M) Copper (II) chloride solution at low temperature by a simple and cost-effective chemical bath deposition (CBD) method. The immersion time of ZnS thin films in copper (II) chloride solution was investigated based on the structural, morphological, optical and optical catalytic activity of the prepared layers. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of CuS: ZnS nanolayers consists of nanocrystals with an approximate diameter of less than 10 nm during the immersion time of 1 min. The particles forming the layers are dense and have good adhesion to the substrate. The energy gap of the layers decreases with increasing copper, which can lead to phase formation. Their significant photocatalytic activities in the photodegradation of Rhodamine B (RhB) dye in aqueous media have been considered, because ZnS:CuS nanocomposite thin films showed light catalytic activity in the RhB degradation in presence of visible radiation, so that the percentage of dye degradation is decreased by increasing the amount of copper and the duration of exposure to visible light due to slowing down the recombination rate of electron–hole pairs. While investigating the optical catalytic activity of the layers, there was no need to homogenize and centrifuge the solution to separate the nanoparticles from it. The main aim of this study is consideration of the effects of CuS amount on the photocatalytic activity of ZnS–CuS nanocomposite under the CBD method of synthesis condition. [ABSTRACT FROM AUTHOR]

Industrial effluents are a leading major threat for water contamination, subsequently which results in severe health associated risks. Hence, purifying wastewater before releasing into the water resources is essential to avoid contamination. In this study, ZnO/Cu-DPA nano-composites were prepared by altering the percentage of Cu-DPA (20%, 30%, 40%, and 50% which are denoted to be ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA) using a simple mechanical grinding process. Several spectroscopic studies were employed such as electron paramagnetic analysis (EPR), powdered X-ray diffractometer (PXRD), UV–Vis absorbance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope to characterize these nano-composites. The photo-catalytic activities of the prepared nano-composites were studied by degrading MB under visible light irradiation. ZnO, ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA degradation efficiencies were determined to be 71.8, 78.5, 77.1, and 66.1%, respectively. Among the composite catalysts, the ZnO/20%Cu-DPA coupled system are demonstrated the best efficiency (87%) for photo-degradation of MB within 80 min when exposed to visible light. The ZnO/Cu-DPA nano-composites had a greater MB photodegradation efficiency than pristine ZnO owing to p-n heterojunction in the linked system. Under visible light irradiation, the ZnO/20%Cu-DPA catalysed the conversion of dissolved O2 to hydroxyl radicals (OH·), triggering the reduction of MB. This suggests that ·OH is the primary specific active radical involved in the photo-catalytic decomposition of MB. Furthermore, EPR analysis indicates the existence of ·OH in the photo-catalytic system. The proposed nano-composites (ZnO/20%Cu-DPA) reusability was investigated across three cycles as the most efficient photo-catalyst. The results show that, the ZnO/Cu-DPA nano-catalyst is a potential candidate for the remediation of dirty water. [ABSTRACT FROM AUTHOR]

In this work, successful nanocomposites composed of different ratios of reduced graphene oxide and copper sulphide (xCuS–rGO) were fabricated to aid in treating water contaminated with organic dyes. XRD, TEM, SEM, XPS, IR, EDX and BET were applied for the characterization of (CuS–rGO). The photocatalytic strength of the prepared nanocomposites was evaluated using artificial sunlight irradiation. The nanocomposites were tested for their ability to degrade both anionic and cationic organic dyes, including amaranth and rhodamine B (RhB). The excellent photocatalytic strength of our composites, relative to pristine CuS and rGO, was interpreted as rGO sheets being very porous. In addition, the charge moved efficiently from rGO to CuS. The combined properties enhanced the efficiency of photodegradation of CuS–rGO composite across the dyes under the illumination of simulated sunlight. The electron transportation from rGO sheets to the CuS conduction band enhances the charge separation and transportation. The role of superoxide radicals in photocatalytic degradation was unveiled and the interactions between the studied dyes and our catalysts were investigated by density functional theory study and scavenging investigation. This work gives new ideas about the preparation and properties of (CuS–rGO) composites and their broad application in solving environmental problems. [ABSTRACT FROM AUTHOR]

This study proposes a new method for producing α-Fe2O3–CuO nanocatalyst that is both cost-effective and ecologically benign. The α-Fe2O3–CuO nanocomposite was prepared via moderate thermal oxidative decomposition of copper hexacyanoferrate. Its structure and surface morphology are affirmed via XRD, SEM, FTIR, EDX, TEM, XPS, and VSM. In the presence of H2O2, α-Fe2O3–CuO is employed as a heterogeneous catalyst to stimulate thermally induced degradation of dyes such as direct violet 4, rhodamine b, and methylene blue. The synergistic effect of Fe2O3 and CuO enhanced the catalytic activity of the nanocomposite compared to Fe2O3 and CuO separately. The effectiveness of DV4 degradation is optimized by evaluating multiple reaction parameters. The reaction rate increased substantially with the temperature, revealing its key role in the degradation process. Higher H2O2 levels and the inclusion of inorganic anions like chloride or nitrate also sped up the degradation process. While sulfate and humic acid, particularly at high doses, slowed it. The mechanism of H2O2 activation on α-Fe2O3–CuO is studied. The measurements of chemical oxygen demand and total organic carbon indicate that all dyes are highly mineralized. The remarkable performance and stability of this nanocomposite in removing diverse dyes render it a promising option for wastewater remedy. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and environmentally friendly method for the green synthesis of SnO2–ZnO/bentonite nanocomposite in the presence of Acroptilon repens flower extract as a reducing and stabilizing agent. The synthesized nanocomposite was characterized using various techniques to investigate their structural properties and morphology. The photocatalytic degradation of the organic dye, eriochrome black-T (EBT) under solar irradiation and in the presence of synthesized nanocomposite was investigated. The results indicated that the nanoparticles were well immobilized onto bentonite as a support with minimum agglomeration. Moreover, the results of photocatalytic reactions showed that SnO2–ZnO/bentonite nanocomposite could remove the dyes in just 2.5 h and the degradation efficiencies approached 100% indicating the excellent performance of the catalyst. The kinetic study revealed that degradation of EBT in presence of the SnO2–ZnO/bentonite nanocomposite obeys first-order kinetics with the rate constant of 1.75 × 10–2 min−1. Furthermore, the biosynthesized nanocomposite exhibited a stable performance and high tolerance to the reaction conditions and was reused in three cycles with negligible loss of activity. [ABSTRACT FROM AUTHOR]

Present study reports the hydrothermal synthesis procedure to prepare the facile and sustainable orthorhombic Molybdenum trioxide (α-MoO3) nanoparticles (NPs) for the degradation of thymol blue dye. Synthesized α-MoO3NPs was characterized by FTIR, XRD, Zeta-potential, SEM, and TEM to investigate the functionalities, texture, size, and morphology of α-MoO3 NPs. The average size was calculated up to 68 ± 5 nm. The α-MoO3NPs was successfully applied to degrade toxic organic dye (thymol blue) in aqueous media. To achieve maximum percentage degredation of dye different parameters were optimized, including a catalyst dose, reaction time, effect of microwave irradiation at low power, reproducibility of catalyst. At optimum conditions, the fabricated α-MoO3NPs-based heterogeneous nano-catalyst was highly efficient for degrading thymol blue dye in aqueous media; the percentage degradation was obtained up to 99% within 60 s just using 120 µg of α-MoO3NPs was used under the microwave radiations. The heterogeneous nano-catalyst shows excellent performance and is highly efficient as compared to previously reported work. The schematic diagram for the degradation of thymol blue dye using prepared MoO3 nano-catalyst [ABSTRACT FROM AUTHOR]

Results of studying features of spinel structure formation in the CoO–Fe2O3 system obtained using various production techniques are presented. The possibility of forming cobalt (II) ferrite at the surface of a number of carriers is considered. It is shown that depending upon structural characteristics of the substrate, the cobalt (II) ferrite formed has different dispersion and degree of reversibility. It is established that increased catalytic activity in the process of purification of an aqueous solution from an organic dye during hydrogen peroxide breakdown of synthesized materials with an organic carrier has been established. [ABSTRACT FROM AUTHOR]

Advance the photo-activity of the nano-sized ZnO photocatalyst is an essential factor in remediation of environmental pollution caused by industrial-organic dyes. Blends of transition elements including Mn, Fe and Co ions were employed to modify the energy gap and the visible absorption state tail of ZnO as well as inhibit the charge carriers recombination by their flexible oxidation states. Five nanocatalysts composed of ZnO, Zn0.97Mn0.015Fe0.015O, Zn0.97Mn0.015Co0.015O, Zn0.97Fe0.015Co0.015O and Zn0.97Mn0.01Fe0.01Co0.01O were simply synthesized. All the prepared compositions have a single phase of ZnO wurtzite structure. Both compositions of Zn0.97Fe0.015Co0.015O and Zn0.97Mn0.01Fe0.01Co0.01O have high sensitive responses to visible light spectrum owing to band gap reduction and formation of absorption state tails. The SEM images demonstrated that the kind of the transition metal blends added to ZnO powder have a significant effect on its morphology. Remarkably, the addition of (Fe, Co) mixture to ZnO powder leads to formation of homogenous rods structure besides very fine spherical particles. All modified ZnO samples revealed enhanced photocatalytic activity but Zn0.97Fe0.015Co0.015O powder possesses the greatest efficiency (98%) for 25 ppm Reactive Yellow 145 dye in 75 min of solar illumination with acceptable stability. In addition, Zn0.97Fe0.015Co0.015O catalyst revealed high photo-removal activity for 25 ppm Rhodamine B and malachite green with measured efficiencies of 94 and 91% in 75 min, respectively. The suitable catalyst dose was identified to be 0.04 g (100 mL solution) and the main effective radicals are the hydroxyl (·OH) species. [ABSTRACT FROM AUTHOR]

Due to its small particle size, high specific surface area, functional capability and long-term stable fluorescence, nanodiamond (ND) has been widely used in biomedical applications including fluorescent probes, drug delivery and biological imaging. Nevertheless, the metabolism of ND and its derivatives is not yet well understood for diverse biomedical applications. In this study, to evaluate the cytotoxicity and biodistribution of the ND derivative, pure ND was functionalized with ethylenediamine (EDA) as a linker (ND-EDA) and then covalently labeled with an organic fluorescent dye called calcein. The modified ND is referred to as ND-EDA-calcein. Even at the maximum dose of 0.1 mg·mL−1, the in vitro results for ND-EDA-calcein against HepG2 and LO2 cell lines showed negligible cytotoxicity, which was in line with the in vivo observations. In addition, it was found that following an intraperitoneal injection, ND-EDA-calcein could be accumulated mostly in the liver and kidney of the mice but not in the spleen. It is interesting to note that after 5 days following intraperitoneal injection, mice can totally metabolize the elimination of ND-EDA-calcein outside of their bodies. Therefore, our findings suggested that NDs can be considered for various nanomedicine applications including drug delivery and biomarkers. [ABSTRACT FROM AUTHOR]

There has been a lot of attention on water pollution by dyes in recent years because of their serious toxicological implications on human health and the environment. Therefore, the current study presented a novel polyethylene glycol-functionalized graphene oxide/chitosan composite (PEG-GO/CS) to remove dyes from aqueous solutions. Several characterization techniques, such as SEM, TEM, FTIR, TGA/DTG, XRD, and XPS, were employed to correlate the structure–property relationship between the adsorption performance and PEG-GO/CS composites. Taguchi's (L25) approach was used to optimize the batch adsorption process variables [pH, contact time, adsorbent dose, and initial concentration of methyl orange (MO)] for maximal adsorption capacity. pH = 2, contact time = 90 min, adsorbent dose = 10 mg/10 mL, and MO initial concentration = 200 mg/L were found to be optimal. The material has a maximum adsorption capacity of 271 mg/g for MO at room temperature. With the greatest R2 = 0.8930 values, the Langmuir isotherm model was shown to be the most appropriate. Compared to the pseudo-first-order model (R2 = 0.9685), the pseudo-second-order model (R2 = 0.9707) better fits the kinetic data. Electrostatic interactions were the dominant mechanism underlying MO sorption onto the PEG/GO-CS composite. The as-synthesized composite was reusable for up to three adsorption cycles. Thus, the PEG/GO-CS composite fabricated through a simple procedure may remove MO and other similar organic dyes in real contaminated water. [ABSTRACT FROM AUTHOR]

In this study, we used solvent assisted mechano-synthesis strategies to form multifunctional organic–inorganic nanocomposites capable of removing both organic and inorganic contaminants. A zeolite X (Ze) and activated carbon (AC) composite was synthesized via state-of-the-art mechanical mixing in the presence of few drops of water to form Ze/AC. The second composite (Ze/L/AC) was synthesized in a similar fashion, however this composite had the addition of disodium terephthalate as a linker. Both materials, Ze/AC and Ze/L/AC, were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), Accelerated Surface Area and Porosimetry System (ASAP), and thermal gravimetric analysis (TGA). The SEM–EDS displayed the surface structure and composition of each material. The sodium, oxygen and carbon contents increased after linker connected Ze and AC. The P-XRD confirmed the crystallinity of each material as well as the composites, while FTIR indicated the function groups (C=C, O–H) in Ze/L/AC. The contaminant adsorption experiments investigated the effects of pH, temperature, and ionic strength on the adsorption of methylene blue (MB) and Co(II) for each material. In MB adsorption, the first-order reaction rate of Ze/L/AC (0.02 h−1) was double that of Ze/AC (0.01 h−1). The reaction rate of Ze/L/AC (4.8 h−1) was also extraordinarily higher than that of Ze/AC (0.6 h−1) in the adsorption of Co(II). Ze/L/AC composite achieved a maximum adsorption capacity of 44.8 mg/g for MB and 66.6 mg/g for Co(II) ions. The MB adsorption of Ze/AC and Ze/L/AC was best fit in Freundlich model with R2 of 0.96 and 0.97, respectively, which indicated the multilayer adsorption. In the Co(II) adsorption, the data was highly fit in Langmuir model with R2 of 0.94 and 0.92 which indicated the monolayer adsorption. These results indicated both materials exhibited chemisorption. The activation energy of Ze/L/AC in MB adsorption (34.9 kJ mol−1) was higher than that of Ze/L/AC in Co (II) adsorption (26 kJ mol−1). [ABSTRACT FROM AUTHOR]

This is due to the fact that TiO2 has the wide energy gap and short life and its photocatalytic active only under ultraviolet light, and so its application is greatly limited. TiO2 can form a heterojunction if combined with other semiconductors to enhance its photocatalytic ability under visible light. In this study, a TiO2/Bi2SiO5 photocatalyst with n–n heterojunction was successfully synthesized by the sol–gel method and hydrothermal method. Eggshell waste has long been used as fertilizer to grow plants or food additives for livestock, or as an adsorbent in metal ions and organic dyes. Using eggshell as a carrier of photocatalyst can possibly reduce its cracking of the substrate. The photocatalyst was deposited on eggshell powder by solid state dispersion (SSD). It was analyzed for the adsorption and degradation of methylene blue by various compositions of the photocatalysts and eggshell powder under visible light. The results demonstrated that the ratio of TiO2/Bi2SiO5: eggshell powder at 1:1 could have the best removal ability. To better facilitate the recovery of the photocatalyst from the aqueous solution, we used the techniques of electrostatic spraying and electrospinning to prepare nylon 6,6 nanofiber membranes with various composite photocatalyst (TiO2/Bi2SiO5/Eggshell/Nylon 6,6 NFM). The nanofiber membrane degraded 98% of methylene blue after 30 min of dark adsorption and 1 h of visible light irradiation. [ABSTRACT FROM AUTHOR]

Context: The organic solar cells (OSCs) are being developed with the goal of improving their photovoltaic capabilities. Here, utilizing computational methods, six new nonfullerene acceptors (NFA) comprising dyes (A1–A6) have been created by end-group alterations of the Y123 framework as a standard (R). Methods: The DFT-based investigations at B3LYP/6-31G + (d,p) level were applied to evaluate their properties. The planar geometries associated with these structures, which lead to improved conjugation, were validated by the estimation of molecular geometries. Dyes A1–A6 have shorter Egap than R, according to a frontier molecular orbital (FMO) investigation, which encourages charge transfer in them. The dyes with their maximum absorption range were shown by optical properties to be 692–711 nm, which is significantly better than R with its 684 nm range. Their electrostatic and Mulliken charge patterns provided additional evidence of the significant separation of charges within these structures. All the dyes A1–A6 had improved light harvesting efficiency (LHE) values as compared to Y123, highlighting their improved capacity to generate charge carriers by light absorption. With the exception of dye A4, all newly developed dyes might have a superior rate of charge carrier mobility than R, according to reorganization energies λre. Dyes A3 and A4 had the greatest open-circuit voltage (Voc). Dye A3 exhibited improvement in all of its examined properties, making it a promising choice in DSSC applications. [ABSTRACT FROM AUTHOR]

Context: Since 1991 when Grätzel et al. improved the conversion efficiency of dye-sensitized solar cells to 7.1% by applying nano technology as the first time, the researches on dye-sensitized solar cells have received widely attentions. The organic dye without precious metals has a lower cost, which is easily to get synthesized and its structure is easily decorated, owing a higher photoelectric conversion efficiency at the same time. Therefore, in recent years, the organic dye has attracted people's attentions more and more. In order to better understand the relationship between structure and properties of dye molecules, with ZL003 as a prototype, molecular modifications are then made and a scheme, with rigid fused π-bridge comprising electron-rich and deficient segments. The calculated results indicate that the π-bridge containing dithienopyrrolobenzothiadiazole and dipyrrolo-dithienobenzothiadiazole as π-bridge has been demonstrated to be successful to significantly redshift the absorption maximum wavelength, extend the lifetime of the first excited state, and decrease the energy gap between the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO). It is hoped that the calculation result of this paper would provide theoretical basis for the experimental synthesis of more efficient dye molecules. Method: All calculations were performed in Gaussian 09 program package. The ground state geometries (S0) and the first excited state (S1) were optimized using density function theory (DFT) with the hybrid function B3LYP functional, coupled with the 6-31G(d, p) basis set for optimization of molecule ground state conformations. TD-DFT calculations of excited state energies and absorption spectra were performed using MPWPW91 functional combined with the 6–31 + G (d) basis set. [ABSTRACT FROM AUTHOR]

In this study, the chemical pechini sol-gel method was used for the simple fabrication of Fe0.5Mn0.5Co2O4/Fe2O3 as a new nanocomposite at 400, 600, 800, and 1000 oC. The fabricated products at 400, 600, 800, and 1000 oC were encoded as E400, E600, E800, and E1000, respectively. The fabricated nanocomposites were identified using several devices such as XRD, N2 adsorption/desorption analyzer, FT-IR, EDS, UV–Vis diffuse reflectance spectrophotometer, and field emission scanning electron microscopy. The average crystallite size of the E400, E600, E800, and E1000 products is 80.31, 123.25, 130.75, and 141.36 nm, respectively. The FE-SEM showed that the E400 sample consists of rods, spheres, and irregular forms with an average diameter of 337.50 nm. Also, the E600 and E800 products consist of spheres and irregular shapes with an average diameter of 446.96 and 854.52 nm, respectively. Besides, the E1000 product comprises of cubic, sphere, and irregular shapes with a mean diameter of 1019.88 nm. The synthesized nanocomposites were used for the efficient photocatalytic degradation of safranin dye. In the presence of H2O2, 0.1 g of the synthesized nanocomposites completely decompose 50 mL of about 25 mg/L of safranin dye at pH equals 8 in 25 min. [ABSTRACT FROM AUTHOR]

For the first time an advanced carbon sorbent modified with salicylic acid for medicinal and veterinary applications was synthesized by the adsorption from solutions. Optimal parameters of the modification were determined: Solvent, "carbon sorbent–modifier" ratio, concentration of salicylic acid, equilibration time of the process in the "sorbent–salicylic acid solution" system, pH, and process temperature. The effect of the drying parameters on stability and amount of oxygen-containing groups on the carbon sorbent surface after modification was established. Physicochemical properties of the carbon sorbent and sorbents modified with different concentrations of salicylic acid were investigated: textural characteristics, qualitative and quantitative compositions of the surface functional groups, and amount of the deposited modifier. The possibility of salicylic acid desorption into the media simulating biological fluids, particularly the gastrointestinal medium, was explored. Adsorption characteristics of the carbon sorbent and sorbents modified with different concentrations of salicylic acid with respect to organic dyes—methylene blue and metanil yellow in a wide range of operating concentrations—were revealed. [ABSTRACT FROM AUTHOR]

The broad application of organic dyes such as 4-nitrophenol (4-NP), rhodamine 6G (R6G), and methylene blue (MB) as raw materials in the manufacture of dyes, explosives, pesticides, preservatives, and pharmaceuticals caused serious damage to the environment, particularly aquatic ecosystems. In this study, silver nanoparticles decorated ZnO/Fe3O4 (Ag/ZnO/Fe3O4) nanocomposite was used as a catalyst to reduce 4-NP, R6G, and MB in the presence of sodium borohydride as a reducing agent. Silver nanoparticles decorated ZnO/Fe3O4 composite was synthesized via a simple and inexpensive chemical reduction method. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the particles. The surface-enhanced Raman spectroscopy (SERS) activity of the nanocomposites due to AgNPs was used to monitor catalytic reactions with detailed spectral features using SERS. Thus, the catalytic transformation of 4-nitrothiophenol (4-NTP) into 4-aminothiophenol (4-ATP) was traced using SERS. The magnetic property of the nanocomposites enables its repeated use. Easy recovery of the particles from the reaction solution was achieved and run for fifteen cycles with no significant loss of its efficiency. [ABSTRACT FROM AUTHOR]

Electrocoagulation was demonstrated for the effective removal of organic dyes, waxes, and sodium silicate from batik wastewater. For the first time, the reuse of an electrocoagulated batik sludge (EBS) by converting it into an adsorbent for Acid Red 18 (AR18) dye removal is reported. The EBS sample was dried in an oven to produce the raw EBS (REBS) adsorbent, which was then calcined to remove its organic constituents to give calcined EBS (CEBS) adsorbent. Nitrogen adsorption–desorption isotherm, scanning electron microscope-energy-dispersive X-ray (SEM–EDX), and Fourier transformed infrared (FTIR) analyses were applicable to reveal the adsorbents' physical and chemical characteristics. Effect of different preparation methods (REBS and CEBS), initial solution pH (3–9), adsorbent dosage (0.1–0.4 g/200 mL), initial concentrations (25–100 mg/L), and temperature (30–50 °C) on the adsorption of AR18 dye as well as regeneration and leaching study of the adsorbent were elucidated. The isotherm results indicated that the experimental data were best fitted to the Langmuir model with maximum adsorption capacity, qmax of 51.62 mg/g. Meanwhile, the adsorption of AR18 dye onto REBS mainly occurred through chemisorption as the kinetic data were best described by the pseudo-second-order model. REBS appeared to be a potential adsorbent for the removal of AR18 dye due to its simple preparation method, good adsorption capacity, and reusability performance. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (RGO) with good water dispersibility and excellent adsorption performance was successfully prepared using sodium borohydride (NaBH4) as reductant, and their characterization and adsorption performance for Basic Red13 (BR13) and Cu2+ were analyzed. The results showed that RGO had an obvious graphene-like structure with the C/O ratio of 3.19, while the C/O ratio of graphene oxide (GO) was only 1.81. The reason for the good water dispersibility of RGO was the retention of partial oxygen-containing groups, especially carboxyl groups. The adsorption of RGO for BR13 and Cu2+ was typical monolayer physisorption, which could be well-described by pseudo-first-order and Langmuir isotherm models. The maximum adsorption capacities of RGO were 1674.01 mg/g for BR13 at pH = 13 and 164.72 mg/g for Cu2+ at pH = 6, which much higher than the corresponding values of 1258.65 mg/g and 123.14 mg/g for GO. In particular, the adsorption capacity of RGO for BR13 was the highest value reported so far. Moreover, no significant loss of adsorption performance was observed even after five cycles. This work suggested that reduced graphene oxide was an efficient adsorbent for the removal of organic dyes and heavy metal ions from water, which had great potential in pollution control applications. [ABSTRACT FROM AUTHOR]

The present work aims to fabricate of graphene oxide (GO) nanosheets-yttrium oxide (Y2O3)–silicon oxide (SiO2) ternary nanostructures as high photo-degradation activity against pollutants of organic dyes. The GO nanosheets were added to Y2O3/SiO2 nanostructures with ratios 5%, 10% and 15%. The structural and photo-degradation characteristics of Y2O3/SiO2/GO nanostructures were studied. The structural characteristics included X-ray diffraction (XRD) and scanning electron microscope (SEM). Results of X-ray indicated that no reaction between components. SEM micrographs showed high distribution of GO nanosheets inside the Y2O3/SiO2 nanostructures. The photo-degradation against organic dyes improved from 1.17% for Y2O3/SiO2 nanostructures to 52% when the concentration of GO nanosheets reached 15 wt% at time (45 min). The dye concentration reduced with an increase in the nanomaterials content and irradiation time. Finally, the obtained results indicated that the Y2O3/SiO2/GO nanostructures have individual activity for photo-degradation of organic dyes which can be considered as key to remove the pollutants of organic dyes with elevated activity, short time, low nanomaterials concentration and few cost compared of others nanomaterials. [ABSTRACT FROM AUTHOR]

This article reports preparation of Bi2WO6 using solid-state and solution combustion methods. Different physicochemical characterization techniques such as XRD, SEM, TEM, BET-N2 adsorption study, UV–vis, XPS and photoluminescence spectroscopy were used to examine crystalline phase, optical and morphological properties of synthesized Bi2WO6 samples. The evaluation of prepared photocatalyst for methyl orange degradation, Cr(VI) reduction under visible light and rhodamine B degradation under direct sunlight was carried out. The sample prepared by a solution combustion route, exhibited superior photocatalytic activities than that prepared by a traditional solid-state route. [ABSTRACT FROM AUTHOR]

A biogenic synthesis of Ag NPs adorned Helleborus niger extract-modified graphene oxidenanohybrid material has been demonstrated. Initially, the Helleborus niger extract was functionalized on the surface of graphene oxide. The polyphenolic groups of plant phytochemicals facilitated the green reduction of Ag ions as well as GO to afford the Ag/H.niger@rGO nanocomposite. The nanocomposite was characterized using FT-IR, FE-SEM, EDX, elemental mapping, TEM and XRDanalysis.Towards its application, it was found to be an efficient catalyst in the reductive degradation of toxic water pollutant organic dyes like Methylene blue (MB)and 4-nitrophenol (4-NP) over NaBH4 at room temperature. Time dependent UV–Vis spectroscopy was used to follow up the reactions which revealed that the reactions were completed within very short time (50–60 s). After the chemical applications we also explored the material biologically in the resistance of human colon cancer and thereby studied the cytotoxicity over two standard cell lines, HT-29 and Caco-2. The conventional MTT assay was carried out over them which revealed an increase in % cell viability dose dependently. In addition, DPPH radical scavenging test was performed for studying anti-oxidant activity. The IC50 values observed in the two cell lines were 368.2 μg/ml and 254.2 μg/ml respectively. [ABSTRACT FROM AUTHOR]

In this paper, a comparative study about the photocatalytic performance of pure Anatase/Rutile mixed-phase Titania (AR-TiO2) nanoparticles and their nanocomposites with multi-walled Carbon Nanotubes (MWCNTs) & 'Platinum-like' Tungsten Carbide (WC) has been carried out. Nanostructured amorphous-titania was synthesized through the Sol–gel route followed by its crystallization through calcination at ~ 550 °C, while the MWCNTs-TiO2 and WC-TiO2 nanocomposites were produced by the Bath Ultrasonication of their individual aqueous mixtures with the AR-TiO2 nanoparticles. These nanocatalysts were further characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), UV–Visible Spectrophotometry, and Photocatalytic decomposition testing using Methylene Blue (MB) dye. The XRD-based structural examinations determined the occurrence of anatase/rutile mixed phases of titania in all nanocatalysts alongside the MWCNTs and WC in their relevant nanocomposites having connected through physical means only. The chemical analysis was conducted through the FT-IR which also confirmed that there are no chemical interactions in-between the constituents of nanocomposites. The SEM-based morphological studies revealed that the AR-TiO2 nanoparticles were spherical in shape, having average sizes of ≈ 20 nm which were forming flower-like structures around the ends of MWCNTs and were making agglomerates in MWCNTs-TiO2 and WC-TiO2 nanocomposites, respectively. The Optical bandgaps (Eg) were measured through UV–Visible spectrophotometry where the Eg of AR-TiO2 nanoparticles (~ 2.69 eV) was decreased by the mixing of MWCNTs (~ 2.56 eV) while an increasing trend was found with the WC addition (~ 2.75 eV). Finally, the photocatalytic studies showed that MWCNTs-TiO2 and WC-TiO2 nanocomposites have higher efficiencies than the pure AR-TiO2 nanoparticles in the visible and UV-A (λ ~ 366 nm) ranges, respectively. [ABSTRACT FROM AUTHOR]

Fluorescent organic dyes play an essential role in the creation of new "smart" materials. Fragments and functional groups capable of free rotation around single bonds can significantly change the fluorescent organic dye's electronic structure under analyte effects, phase state transitions, or changes in temperature, pressure, and media polarity. Dependencies between steric and electronic structures become highly important in transition from a solution to a solid-state. Such transitions are accompanied by a significant increase in the dye molecular structure's rigidity due to supramolecular associates' formation such as H-bonding, π···π and dipole–dipole interactions. Among those supramolecular effects, H-bonding interactions, first of all, lead to significant molecular packing changes between loose or rigid structures, thus affecting the fluorescent dye's electronic states' energy and configuration, its fluorescent signal's position and intensity. All the functional groups and heteroatoms that are met in the organic dyes seem to be involved in the control of fluorescence via H-bonding: C-H···N, C-H···π, S = O···H-C, P = O···H, C-H···O, NH···N, C − H···C, C − H···Se, N–H···O, C − H···F, C-F···H. Effects of molecular packing of fluorescent organic dyes are successfully used in developing mechano-, piezo-, thermo- fluorochromes materials for their applications in the optical recording of information, sensors, security items, memory elements, organic light-emitting diodes (OLEDs) technologies. [ABSTRACT FROM AUTHOR]

Organic synthetic dyes have been extensively used in the leather, textile, rubber, plastic and paper industries. The excessive exploitation of organic dyes especially Eosin Y (EY) have serious effects on the human life because these dyes are non-biodegradable, toxic and carcinogenic in nature. Thus, removal of EY from aqueous environment through reliable and effective method is an essential task. To tackle out this problem an exceptional polyvinylpyrrolidone caped copper oxide nanoflakes (PVP-CuO NFs) were engineered and employed as photocatalyst for the degradation of EY in aqueous system. The prepared PVP-CuO NFs were characterized via advanced analytical tools to evaluate size, topography, crystallinity and functionalities of engineered material. Through SEM examination nanoflakes like morphology of PVP-CuO was confirmed while the average size of the prepared material was calculated 31.8 nm, respectively. The high intensity of XRD peaks of CuO at (002 and 111) witness exceptional crystalline structure of prepared material. The EDX analysis confirms the percent element of (74.48%) copper and (17.21%) for oxygen atom. The fabricated PVP-CuO was employed as nanocatalyst for the degradation of EY dye with minimum dose of 0.25 µg under the 3 min time with highest degradation percentage 98.6%. The effectiveness and reliability of proposed hetero-catalyst was tested by repeating the experiment 5 times to check its reusability. After 5 repeated experiments the degradation efficiency of nanocatalyst was decreased from 98.6 to 86% only, which highlights excellent reusability of catalyst to be used for several times. Excellent degradation percentage and reusability profile of PVP-CuO nanocatalyst suggests that the engineered catalyst could be used at commercial level. [ABSTRACT FROM AUTHOR]

In the present investigation a promising conducting polymer, Polyaniline (PANI), and ZrO2-PANI nanocomposite are used for photocatalytic degradation of Carbol Fuchsin (CF) dye. Both materials were prepared via the in-situ polymerization method. Various nano-characterization techniques were used to investigate the fabricated materials. The structural investigation of ZrO2 and ZrO2-PANI nanocomposite was performed using X-ray diffraction (XRD). From this investigation, it was observed that ZrO2 belongs to the crystalline tetragonal phase possessing a crystallite size of 15.80 nm. The SEM analysis shows the flakes arrangement for undoped ZrO2, while improved agglomeration has been observed for modified ZrO2-PANI nanocomposite. The Raman shifts can be observed from Raman spectroscopy for both the fabricated materials. Organic dyes are considered to be persistent organic pollutants (POP's) that are toxic in nature. Here one of the POP dyes, CF was used in the photocatalytic efficiency of ZrO2 and ZrO2-PANI nanocomposite. The prepared polymerized catalysts are porous, possessing a high surface area with a tuned band gap, and are found very persistent, and rapid, for the water purification process via the Advanced Oxidation Process. The fabricated catalyst degrades the CF dye within 30 min. [ABSTRACT FROM AUTHOR]

In this work, sulphur doped copper ferrites (S-CuFe2O4) photocatalysts were successfully synthesized for the first time using the facile hydrothermal method. The as-synthesized photocatalysts were characterized through XRD, Raman, TGA, FT-IR, UV–Vis-DRS, SEM, EDX and PL techniques. The results revealed that doping with sulphur has been found to be a suitable alternative that causes strain in the lattices as anions replace the oxygen from the CuFe2O4 nanostructures. Due to sulphur dopants, photocatalysts are able to efficiently trap and transfer the photoinduced charges, which readily suppress charge recombination. A UV–Vis spectrophotometer was used to monitor the degradation of selective toxic organic dyes (RhB, CR, MO, and CV) in aqueous media. The dye degradation results provide evidence for the surprisingly superior performance of S-CuFe2O4 over pristine CuFe2O4. On the basis of its efficiencies, this work can be assigned as an excellent candidate for photocatalysis science. [ABSTRACT FROM AUTHOR]

Vanadium-doped zinc sulfide quantum dots complexed with TiO2 have been designed using the sol–gel technique and characterized using analytical techniques, such as X-ray diffraction analysis (XRD), UV–Vis diffuse reflectance spectra (DRS), Fourier transforms Infra Red (FTIR), Brunauer–Emmett–Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscopy (TEM). The X-ray diffraction analysis of the composite material showed sharp peaks corresponding to both TiO2 and ZnSQDs. The FTIR analysis exhibits a strong and broad absorption at 807 cm−1 indicating the assimilation of vanadium metal in the ZnSQDs lattice. The DRS spectra showed a bathochromic shift of 25 nm in the synthesized V-ZnSQDs@TiO2 composite compared with the pure sample. The photocatalytic performance of the synthesized composite was tested by studying the degradation of two different chromophoric organic dyes, rhodamine B (RhB), methylene blue (MB) and a drug derivative paracetamol (PCM) in aqueous suspension under UV-light illumination. Among the synthesized materials, the composite (V-ZnSQDs@TiO2) was established to be more active than the pure ZnSQDs, TiO2, and V-ZnSQDs for the degradation of compounds under investigation. The activity of the synthesized catalyst was also tested for the mineralization of all compounds by measuring the depletion in total organic carbon (TOC) at different irradiation times. The results showed that the catalyst degrades the compounds and mineralizes them efficiently. The primary reactive species involved in the photodegradation reaction were determined by quenching studies, terephthalic acid, and NBT probe methods. A probable mechanistic pathway for the decomposition of compounds has been proposed. [ABSTRACT FROM AUTHOR]

Here, we synthesized metal-free organic dye (CCPICPB) with two carbazole donor groups and two anchoring groups that exhibit a panchromatic absorption in the near-infrared range of up to 750 nm. To study the photophysical properties of synthesized CCPICPB dye, the UV–Vis and cyclic voltammetric experiments were studied and the obtained results were validated with theoretical simulation studies. After that, the solvothermal approach is used to synthesize pristine anatase and calcium (Ca)-doped TiO2 microspheres with a smooth morphology. These microstructures are examined in depth using XRD, electron microscopy and electrochemical analysis methods. On TiO2 and Ca-doped TiO2 photoanode materials, we first evaluated the performance of CCPICPB dye. Upon our optimized experimental condition, the 3% Ca-TiO2 photoanode-based device exhibits an efficiency of 4.04%, which is greater than that of the pristine TiO2 photoanode-based device (2.93%). Because of the quicker electron transport in the Ca-TiO2 film, the short-circuit current density and efficiency of DSSCs were improved. Moreover, when the CCPICPB dye was used as a co-sensitizer with the common Ru(II) dye (Z907), interestingly it showed the highest efficiency (6.11%) when compared with Z907 alone (5.12%). This improved efficiency of the co-sensitized device resulted from greater VOC conjugated with improved JSC. The JSC was improved because CCPICB dye could compensate for the photocurrent loss caused by redox electrolyte while the VOC was improved because electron recombination was inhibited under the co-sensitization conditions. [ABSTRACT FROM AUTHOR]

In this work, two new copper-based coordination polymers (CPs), {[CuI(H2PO4)(dpe)]5(dpe)0.5(H2O)7}n (Cu-dpe(I)) and {[CuII(HPO4)(dpe)(H2O)](H2O)3}n (Cu-dpe(II)) (dpe = 1,2-di(4-pyridyl)ethylene), had been successfully constructed by hydrothermal method and solvent evaporation method, respectively, and their crystal structures were determined by single crystal X-ray diffraction. The differences of structure and properties between these two coordination polymers were discussed. The synthetic temperature caused their structure differences. They both exhibit excellent photocatalytic activity toward the degradation of methylene blue (MB) under visible light. The degradation rates of Cu-dpe(I) and Cu-dpe(II) to MB in 120 min under visible light were 88.1% and 97.2%, respectively. Some active free radicals such as ·OH, ·O2−, e− played an important role in degradation of MB. In addition, luminescent experiment revealed Cu-dpe(I) exhibits a relatively high sensitive and selective detection of Fe3+ ions in water solution via fluorescence quenching which was caused by competitive absorption of excitation wavelength energy between Fe3+ and Cu-dpe(I). [ABSTRACT FROM AUTHOR]

In this paper, the organic pigments indigo and isatin were detected by high performance liquid chromatography (HPLC) in The Mural of Four Buddhas which is in Cave 3 from the ancient Chinese Tiantishan grottoes (Ming Dynasty, East Slope). By analysing the preservation conditions of the mural and the environmental conditions of the place where the Tiantishan grottoes are located, we speculated that the isatin detected in this mural was mainly produced by the oxidative decomposition of indigo by ozone (O3), rather than by photodegradation of indigo. We have used theoretical calculation software Gaussian09 (G09) and Amsterdam Density Functional (ADF) module in the Amsterdam Modeling Suite (AMS) software to simulate the reaction mechanism of O3 oxidation of indigo, and the end products of the oxidation of the natural plant dye indigo by O3 were identified as isatin, C16H10N2O3 and C8H6NO3 using HPLC, fluorescence spectroscopy and high performance liquid chromatography-mass spectrometry(HPLC–MS). This finding confirmed the accuracy of the mechanism of indigo fading by O3 oxidation. These findings provided a theoretical basis for subsequent research into the derivation of natural organic dyes in the face of increasing O3 pollution and for better protection of valuable historical and cultural heritage such as ancient Chinese grottoes murals. [ABSTRACT FROM AUTHOR]

A novel n-MgFe2O4–n-ZnS heterojunction catalyst was employed via two step approach for photodegradation of organic dyes such as Methylene Blue (MB) and Crystal Violet (CV) dyes under visible light irradiation. The synthesized MgFe2O4/ZnS NCs were characterized using PXRD, FTIR, UV–Visible spectroscopy, PL and FESEM analysis which reveals the formation of flake like structure with size as to be ~ 50 nm. The photocatalytic experimental result demonstrates that the MgFe2O4/ZnS nanocomposites (NCs) improve photodegradation performance with 98.0% and 91% decomposition of MB and CV dyes within 120 min illumination during simulated visible light irradiation. From the result, MgFe2O4/ZnS NCs has higher photocatalytic performance than that of MgFe2O4, and ZnS due to efficient separation of the photo-induced electron–hole pairs and effective electron–hole generation transfer by the formation of n-MgFe2O4–n-ZnS heterojunction. Hence, photodegradation performance implies that the synthesized MgFe2O4/ZnS NCs can be effectively utilized in waste water purification systems. [ABSTRACT FROM AUTHOR]

Pure DGEBA epoxy polymer (DGEBA-EP) and MB: DGEBA-EPCPs with different MB dye contents were made using a basic casting suspension system. The enhancing effect of MB organic dye doping on the structural, optical, and dielectric properties has been investigated. The spectra XRD analysis shows an amorphous crystalline peak of approximately 2 θ ∘ = 18 ∘ explaining the pure DGEBA-EP matrix semi-crystalline structure. No XRD-related trends peak related to MB atoms shows a high level of polymer mixture formation free from crystalline MB atoms and total miscibility of MB dye in the DGEBA-EP matrix. Since indirect band gaps are decreasing, light absorption behavior is improved, making the panels suitable for optical laser filter tools. A complete UV–Vis's blocking in wavelength at 675 nm for the high levels of MB organic dye has been enhanced by limiting effect measurements of the MB: DGEBA-EPCPs. Our dielectric parameters pronounced that the MB organic dye is a respectable filler to enhance the electrical AC conductivity of the MB: DGEBA-EPCPs materials. [ABSTRACT FROM AUTHOR]

The zeolite-Y/g-C3N4 composites were successfully synthesized by a facile hydrothermal method. The composition, structure and optical properties of the composites were characterized by infrared spectroscopy, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and other spectral techniques. The as-prepared zeolite-Y/g-C3N4 composite exhibits remarkably enhanced photocatalytic activity for organic dye degradation and nitrogen fixation under visible light irradiation. The optimal hybrid catalyst (YCN-50) shows good photocatalytic activity for methylene blue degradation. The degradation kinetic constant is 26.6 times higher than that of g-C3N4. Photocatalytic degradation of other organic dyes including malachite green, methyl orange and rhodamine B was also studied for comparison. For the photocatalytic nitrogen fixation, the ammonium production rate of zeolite-Y/g-C3N4 composite is 62.7 µmmol g−1 h−1 under the optimal condition, which is 62.7 times higher than that of pure g-C3N4. The high photocatalytic performance of zeolite-Y/g-C3N4 composite is due to the combination of g-C3N4 and zeolite-Y effectively improving the specific surface area and reducing the recombination rate of photogenerated carriers. The zeolite-Y/g-C3N4 composite also shows good photostability and reusability based on recycling experiments. Trapping experiment was also performed to find the responsible radical species for the degradation. The mechanism of dye degradation and nitrogen fixation in the presence of zeolite-Y/g-C3N4 was also discussed. [ABSTRACT FROM AUTHOR]

Background: In the present work, DFT and time-dependent DFT calculations were performed to investigate the role of anchoring groups on the photophysical properties and reveal structure-property correlations of triphenylamine (TPA) derivatives. The selected anchoring groups are tetrazole, acrylamide, hydantoin, and rhodanine. Results: Our results show that the different anchoring groups employed alter the planarity, intramolecular charge transfer properties, and HOMO-LUMO gap and hence influence the optoelectronic properties of the dyes. Although all molecules fulfill the basic requirements with suitable energy levels, band gap, absorption, and charge transfer properties, the dye with rhodanine acceptor (TPA4) was the most promising candidate due to its lowest HOMO-LUMO gap, red-shifted highest λmax absorption value, better ICT pattern, low total reorganization energy, and good electron injection properties. Overall, it is anticipated that the results of this investigation will point to new avenues for the experimental fabrication of remarkably effective metal-free organic dyes for solar cell applications. [ABSTRACT FROM AUTHOR]

The Knoevenagel-Michael cyclocondensation of barbituric acid/1,3-dimethylbarbituric acid, malononitrile, and arylaldehyde derivatives was used to construct a multicomponent green tandem method for the metal-free synthesis of pyrano[2,3-d]pyrimidine scaffolds. At room temperature in aqueous ethanol, photo-excited state functions generated from Na2 eosin Y were employed as direct hydrogen atom transfer (HAT) catalysts by visible light mediated in the air atmosphere. This research looks towards expanding the use of a non-metallic organic dye that is both affordable and readily available. Because of its good yields, energy-effectiveness, high atom economy, time-saving qualities of the reaction, and operational simplicity, Na2 eosin Y is photochemically produced with the least amount of a catalyst. As a result, various ecological and sustainable chemical properties are met. Surprisingly, such cyclization may be carried out on a gram scale, indicating the reaction's potential industrial application. [ABSTRACT FROM AUTHOR]

This work aims to fabricate of manganese oxide (MnO2)/silicon carbide (SiC) nanostructures doped polystyrene (PS)–polycarbonate (PC) blend as promising nanomaterials to utilize in photo-degradation, photonics and optical fields with low cost, lightweight, small content of nanoparticles and excellent properties compared to other nanomaterials. The morphological, optical, electronic and photo-degradation properties of PS–PC/MnO2–SiC nanocomposites were investigated. The surface morphology of PS–PC/MnO2–SiC nanocomposites was analyzed by optical microscope (OM) and field emission scanning electron microscope (FE-SEM) which showed good homogeneous of MnO2–SiC NPs inside the polymeric matrix. The optical characteristics of PS–PC/MnO2–SiC nanocomposites showed that the absorbance increased to 97.58% at wavelength (λ = 260 nm) when the concentration of MnO2/SiC NPs reached (5.2 wt%). The transmittance decreased to 10.57% at λ = 260 nm, and the energy band gaps decreased for both allowed and forbidden indirect transitions about 53.86% and 94.97%, respectively. The pure PS/PC blend and PS–PC/MnO2–SiC nanocomposites were used to analyze the photocatalytic degradation of MO dye. It was found that PS–PC/MnO2–SiC nanocomposites quickly changed the MO colour when exposed to UV-Irradiation with photo-degradation ratio about 54.05% within 90 min at 5.2 wt% MnO2/SiC NPs and this reaction's first-order rate constant was determined to be 0.0088 min−1. The results of the present work showed that PS–PC/MnO2–SiC nanocomposites have practical characteristics in terms of photo-degradation activity against harmful dyes and that these nanocomposites may be used for wastewater treatment and could help resolve environmental protection issues. [ABSTRACT FROM AUTHOR]

Photoelectrocatalytic (PEC) degradation of organic dyes molecules has been proved to be an effective strategy to remove organic dyes from environment and wastewater. However, improving the degradation efficiency so far is still a challenging. Here, a simple and stable photoanode based on TiO2 film on indium tin oxide (TiO2/ITO) was constructed and used for PEC degradation of methyl violet (MV), as an organic dye model. The influences of photoirradiation, applied bias voltage and types of electrolytes on PEC degradation of MV are mainly investigated. The results proves that the PEC degradation performance of TiO2/ITO system can be greatly enhanced by the applied bias voltage on photoanode and the presence of chloride ions. When using potassium chloride (KCl) as electrolyte, the degradation ratio of MV can reach to over 95% in 60 min with a bias voltage of 1.5 V (vs. Ag/AgCl), and a degradation rate constant of 0.053 min−1 can be achieved, which is 17 times higher than that using KNO3 as electrolyte (0.00305 min−1), indicating the applied bias voltage and Cl− play very important roles in the PEC degradation process. In addition, the mechanism for enhanced MV degradation based on applied bias voltage and Cl− was also studied in detail. This work opens the avenue for enhancing the PEC degradation of organic pollutants in aqueous solution, especially that with chloride ions contained, indicating its potential application in industrial dyeing wastewater treatment. The photoelectrocatalytic (PEC) efficiency can be enhanced with the presence of Cl− and the PEC system also has good degradation effect on other dyes which indicating it has practical application potential. [ABSTRACT FROM AUTHOR]

Context: The improvement of new organic flavone-based donor-spacer-acceptor (D-π-A) type dye molecules of the 3-(4-hydroxypiperidin-2-yloxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D1), 7-hydroxy-2-(3,4-dihydroxyphenyl)-3-(piperidin-4-yloxy)-4H-chromen-4-one (D2), and 3-((2-aminopyridin-4-yloxy)methoxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D3) were successfully designed and synthesized for dye-sensitized solar cells (DSSCs). Methods: Here, we discuss the synthesis of flavone compounds as well as their photophysical and electrochemical characterization. Using the Gaussian 09w software, the electronic structures and apsorption spectra have been calculated at the B3LYP, B3PW91, CAM-B3LYP, MPW1PW91, PBEPBE, and ωB97XD theory with the 6-311G(d,p) basis sets. Results: The computed values of the D2 molecule ground state optimized HOMOs-LUMOs energy is well positioned for advantageous charge transfer (CT) into the semiconducting material (TiO2) as well as the electron injection process. With a high power conversion efficiency (PCE) of 3.46% (VOC = 0.718 V, JSC = 7.07 mA cm−2, and FF = 0.68), the D2 compound also demonstrated good photovoltaic (PV) properties. Conclusion: These findings unequivocally demonstrate that altering the D-π-A metal-free organic material electron-withdrawing capacity is a useful strategy for enhancing the optical and electrical characteristics of the organic PV system. [ABSTRACT FROM AUTHOR]

The aim of this research was to fabricate the novel magnetic MIL-53 (Fe)/NaY/NiFe2O4 nanocomposite catalyst by applying an ultrasound-assisted hydrothermal method to be used for the sonocatalytic degradation of methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) organic dyes. The structural and magnetic properties of the MIL-53 (Fe)/NaY/NiFe2O4 nanocomposite was characterized by FESEM, EDAX, AAS, XRD, FTIR, VSM, TEM, BET, and UV–Vis DRS. To study the sonocatalytic performance of the as-fabricated MIL-53 (Fe)/NaY/NiFe2O4 catalyst, the H2O2-assisted degradation of MB, RhB and MO from water solutions was investigated under ultrasound (US) irradiation. The obtained data illustrated that the MIL-53 (Fe)/NaY/NiFe2O4 catalyst had better activity for the sonodegradation of MB, RhB and MO than the MIL-53 (Fe)/NaY, NaY/NiFe2O4, MIL-53 (Fe)/NiFe2O4 or MIL-53 (Fe). The enhanced sonocatalytic performance of the MIL-53 (Fe)/NaY/NiFe2O4 nanocomposite could be corresponded to the rapid generation and separation of charge carriers (electrons and holes) in the MIL-53 (Fe) and NiFe2O4 and their transfer to the NaY zeolite surface. Besides, the recyclability of the MIL-53 (Fe)/NaY/NiFe2O4 sonocatalyst from water solution could be easily achieved via an external magnetic field. The effects of several parameters on the sonocatalytic activity, such as irradiation time, initial dye concentration, catalyst dosage, H2O2 concentration, and US power intensity were also evaluated. The trapping experiments demonstrated that •OH radicals are the main active species in the organic dye degradation. Additionally, the MIL-53 (Fe)/NaY/NiFe2O4 was quite stable since the efficiency of the MB degradation gained in the four run was more than 93%. [ABSTRACT FROM AUTHOR]

Squaraine dyes are organic dyes having strong and narrow absorption properties in the near-infrared region that are widely used in photovoltaic and biomedical applications. In this work, squaraine dye (SA1) was synthesized as a dye sensitizer for a dye-sensitized photocatalytic system, which was composed of SA1 and Pt-loaded TiO2 powder photocatalyst (SA1/Pt-TiO2). The SA1/Pt-TiO2 system exhibited a good hydrogen production performance within 150 h and an apparent quantum yield of 1.4% under 800 nm monochromatic light irradiation. However, during the photocatalytic reaction, the photocatalytic activity of SA1/Pt-TiO2 decreased due to photodecomposition. Ultraviolet–visible absorption spectroscopy, 1H nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry measurements were performed to investigate the mechanism of the decomposition of the squaraine moiety of SA1, the decomposition process, and the structure of the decomposed material. The results show that even without the Pt-loaded TiO2 powder photocatalyst, SA1 undergoes photodissociation, which cleaves the bond between the indoline moiety and the square acid. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) has received much interest as a visible-light-driven photocatalyst for degrading pollutants such as organic dyes and antibiotics. However, g-C3N4 bulk activity could not meet expectations due to its rapid recombination of photogenerated electron–hole pairs and low specific surface area. In our study, melamine was thermally treated one-step in the presence of NH4Cl to produce g-C3N4 nanosheets. The characterizations of surface morphology and optical properties of all g-C3N4 samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), and UV–visible diffuse reflectance spectroscopy. Compared to bulk g-C3N4, g-C3N4 nanosheets demonstrated excellent photocatalytic activities, with approximately 98% RhB removal after 210 min of visible light irradiation. Furthermore, the effect of catalyst dosage, pH, and RhB concentration on the removal percentage dye of g-C3N4 nanosheets was also investigated. h+ and •O2− species were demonstrated as the key reactive species for the RhB. Besides, ECN exposed a tetracycline degradation efficiency of 80.5% under visible-light irradiation for 210 min, which is higher than BCN (60.8%). The improved photocatalytic activity of g-C3N4 nanosheets is due to the restriction of the recombination of photogenerated electrons/hole pairs, as provided by photoluminescence spectra and Nyquist plot. As a result, our research may offer an effective approach to fabricating g-C3N4 nanosheets with high photocatalytic activity and high stability for environmental decontamination. [ABSTRACT FROM AUTHOR]

Ce2(MoO4)3 was prepared using dielectric barrier discharge (DBD) plasma method, co-precipitation method and hydrothermal method, respectively, with water/ethanol (W/O) as solvent, oleylamine (OAm) and oleic acid (OAc) as additives. Preparation method showed significant influence on the morphological and structural properties, as well as photocatalytic performance. Ce2(MoO4)3 synthesized with DBD plasma (MO-P) was mainly flowerlike nanosheets, which were beneficial to promoting electron transfer and providing more space for catalytic activity. Also, MO-P samples exhibited more oxygen vacancies, which were conducive to the photocatalytic performance. What's more, MO-P showed lower PL intensity and narrow energy gap, which implied a slow photoelectron–hole pair recombination rate and an increased electron transfer rate. The degradation rate of methyl orange (50 mg/L) could achieve 98% within 12 min with 0.5 g/L MO-P. Hydroxyl radicals (·OH) and superoxide radicals (·O2−) played a major effect. Plasma synthesis method exhibited potential application prospect in photocatalysts preparation. [ABSTRACT FROM AUTHOR]

The discoveries recommend that the photoinduced conditions of fluorescein-determined go about as impetus for photochemically combining polysubstituted quinolines in ethanol at room temperature under air environment by means of revolutionary Friedländer hetero-annulation of 2-aminoaryl ketone and α-methylene carbonyl compound. This study lays out an original capability for photochemically orchestrating fluorescein. This non-metallic organic dye is economically accessible and modest, producing great outcomes, accelerating the cycle, and achieving a high compound economy. The turnover number (TON) and turnover recurrence (TOF) of polysubstituted quinolines have been determined. This cycle will likewise run on a gram scale, demonstrating the chance of modern applications. [ABSTRACT FROM AUTHOR]

Abstract—First data are reported on the content of plant pigments in bottom sediments of different types in the large shallow Vozhe and Lacha lakes in northwestern Russia. The distribution patterns of chlorophyll a with pheopigments and organic matter in the surface sediments are consistent with sedimentation features. Among the depositional processes, bed erosion, transport of suspended matter, and redeposition dominate in Lake Vozhe, while sedimentation prevails in Lake Lacha. Lake Vozhe is dominated by coarse-grained sediments and shows more pronounced mosaic structure of the sediment complex than Lake Lacha. The lakes show similar values of production indicators for the same type of sediments. Spatial distribution of chlorophyll a and the products of its degradation in the benthal of Lake Vozhe is more heterogeneous than in Lake Lacha. The relative content of the products of chlorophyll degradation in bottom sediments of the studied lakes is about 60%. Average concentration of organic matter calculated considering the areas of bottom sediments of different types in sediments of Lake Vozhe (11.8 ± 2.7%) is 2.3 times less than that of Lake Lacha (27.4 ± 5.5%). The average values of the total content of chlorophyll a and pheopigments characterize Lake Vozhe as a typical mesotrophic water body (38.3 ± 9.3 μg/g dry sediment), and Lake Lacha as an eutrophic basin at the initial stage (72.2 ± 17.7 μg/g dry sediment). The plant carbon calculated from the content of sedimentary pigments amounts an insignificant part of the total primary production of phytoplankton, periphyton, and macrophytes (0.38% in Lake Vozhe and 0.46% in Lake Lacha) and corresponds to 5.3–6.5% of the total organic carbon in bottom sediments. In the absence of anthropogenic pollution, the lakes show signs of eutrophication due to the transboundary transfer and nutrient inflow from the watershed under warming conditions. [ABSTRACT FROM AUTHOR]