Search

In this work, cobalt activated TiO2 photocatalyst have been successfully prepared on graphene oxide (GO) using simple and cost‐effective method to prepare Co‐TiO2/GO nanocomposites for the photocatalytic treatment of methylene blue (MB), representative organic dye, under visible light irradiation. The as‐prepared samples were characterized by X‐ray diffraction (XRD), High resolution transmission electron microscope (HRTEM), X‐ray photoelectron spectroscopy (XPS), UV‐vis diffused reflectance spectra (DRS), Raman spectroscopy and photoluminescence spectroscopy (PL). The characterization results confirmed that Co‐TiO2 catalyst is decorated on the graphene oxide. The photocatalytic efficiency of Co‐TiO2/GO for the degradation of MB was also improved by changing the proportion between Co‐TiO2 and GO. Highest photocatalytic activity was observed for Co‐TiO2 loaded with 5 wt % GO (88.7 %) compared with neat Co‐TiO2 (43.4 %) after 180 min of visible light irradiation. Furthermore, degradation by products was analyzed on Quadrupole Time‐of‐Flight Liquid Chromatography/Mass Spectroscopy (QTOF/LCMS) and the possible degradation pathway was proposed. It is investigated that the Co‐TiO2/GO nanocomposite has potential use in the catalytic degradation of organic contaminants under visible light irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] The exploration of emerging photocatalysts like covalent organic frameworks (COFs) is an essential but challenging endeavor to find sustainable solutions for selective organic transformations. Anthraquinones are envisaged to construct COFs for visible light photocatalysis because their derivatives are employed industrially as oxidation catalysts or organic dyes. Herein, an anthraquinone COF, TpAQ-COF, is successfully constructed with 1,3,5-triformylphloroglucinol (Tp) and 2,6-diaminoanthraquinone (AQ). Then, the selective oxidation of amines over TpAQ-COF is implemented. Amines can be effectively converted into corresponding imines over TpAQ-COF powered with green light and oxygen, during which superoxide radical anion is discerned as the pivotal reactive oxygen species. This work suggests that COFs could inherit the advantages of molecular building blocks for selective reactions powered with broad visible light. [ABSTRACT FROM AUTHOR]

To simulate natural photosynthesis, scientists have developed an artificial Z-scheme system that splits water into hydrogen and oxygen using two different semiconductors. Researchers are striving to improve the performance of Z-scheme systems by improving light absorption, developing redox couples with high stability, and finding new cocatalysts. Here, we report the synthesis and utilization of LaFeO3/g-C3N4 as a Z-scheme system for water reduction to produce hydrogen and organic dye degradation under visible light irradiation. The as-fabricated photocatalyst revealed exceptional activity for H2 production (i.e., 351 µmol h−1g−1), which is 14.6 times higher compared to that of the single-component g-C3N4 (i.e., 24 µmol h−1g−1). In addition, the composite photocatalyst degraded 87% of Methylene Blue (MB) and 94% of Rhodamine B (RhB) in 2 h. Various experimental analyses confirmed that the exceptional performance of the LaFeO3/g-C3N4 Z-scheme catalyst is due to remarkably enhanced charge carrier separation and improved light absorption. The development of this highly effective Z-scheme heterostructure photocatalyst will pave the way for the sustainable development of newly designed Z-scheme scheme systems that will tackle energy and environmental crises. [ABSTRACT FROM AUTHOR]

• Prepared composite nanofiber membrane possesses a good photocatalyst performance. • High degradation activity of organic dyes under visible light. • The composite nanofibers membrane possessed excellent recovery and reuse. • The free-standing membrane is flexible and easy to handle. • The flexibility of the composite nanofibers allows use in a continuous operation. This study proposed an effective method by using photocatalytic composite nanofiber membranes in order to degrade malachite green (MG) and acid red 27 (AR 27) to harmless products. The photocatalytic composite nanofiber membrane, Polyacrylonitrile (PAN) was incorporated with catalyst SiO 2 and TiO 2 photocatalyst. The PAN/SiO 2 -TiO 2 -NH 2 nanofiber membrane was synthesized by electrospinning technique followed by chemical crosslinking. The results of SEM, EDX, FTIR and XRD confirmed the successful preparation of nanofiber membrane. XRD analysis shows the confirmation of SiO 2 and TiO 2 peaks. The result shows that PAN/SiO 2 -TiO 2 -NH 2 nanofiber membrane exhibit the highest degradation with a good distribution of SiO 2 and TiO 2 on the PAN nanofiber membrane surface. The results showed that the complete photodegradation of MG and AR 27 with artificial visible-light was achieved after 9 and 25 min, respectively. In addition, the nanofiber membrane exhibited good stability and reusability for MG and AR 27 photodegradation and has potential to be applied in industrial application. [ABSTRACT FROM AUTHOR]

Abstract SnS 2 exhibits lower photocatalytic activity against organic dyes without N N double bonds due to the SnIV/SnII transition which decreases its degradation efficiency due to the decreased formation of O 2 ∗ − and OH∗ radicals. To upgrade the photocatalytic ability of SnS 2 against dyes without N N bonds, NiO coupling has been adopted and the results obtained are furnished in this paper. By adopting precipitation method, SnS 2 , NiO and SnS 2 NiO nanocomposite was synthesized. Structural, morphological, compositional, functional group analyses of SnS 2 , NiO and SnS 2 NiO nanocomposite were performed by adopting techniques such as XRD, SEM, TEM, XPS, FTIR and PL. The magnetic property of pure SnS 2 got enhanced by coupling with NiO thereby making it suited for magnetic devices. Photocatalytic activities were performed against MB and RhB dyes under visible light. The enhanced degradation ability of the SnS 2 NiO composite may be due to its enhanced oxidation/reduction ability of the electrons and holes generated under the effect of visible light. Highlights • Precipitation method is used to synthesize SnS 2 NiO composite. • Magnetic property of pure SnS 2 is enhanced when coupled with NiO. • The photocatalytic activity of pure SnS 2 got enhanced by forming composite with NiO. • The SnS 2 NiO composite degraded MB better than RhB dye. [ABSTRACT FROM AUTHOR]

Design and usage of efficient visible light photocatalytic systems for wastewater treatment and degradation of organic dyes are of remarkable interest in the fields of environmental protection. In this study, magnetic ZnFe 2 O 4 , ZnFe 2 O 4 /ZnO, Tannin/ZnFe 2 O 4 and Tannin/ZnFe 2 O 4 /ZnO nanocomposites with interfacial contact have been synthesized. The photocatalytic efficiencies of as-obtained samples are analyzed by the degradation of indigo carmine in aqueous solution under UV and visible-light. The degradation ratios of IC are 82% and 99% of IC over the Tannin/ZnFe 2 O 4 /ZnO under the both of UV light and visible light for 90 min, respectively. And after five times recycling, the photocatalytic performance of IC presence the Tannin/ZnFe 2 O 4 /ZnO can even reach nearly 89.79%. The results demonstrate that the Tannin/ZnFe 2 O 4 /ZnO exhibits great photocatalytic efficiency for indigo carmine (IC) compared to their constituent photocatalysts and easy separation from dye solution by magnet. The synergistic interactions between ZnFe 2 O 4 , tannin and ZnO prolonged lifetime of photoexcited carriers leading to greater absorption in both UV and visible light. This nanocomposite was beneficial for separating the photogenerated charge carriers and facilitating electron transfer. Tannin has a decisive role for increasing the photocatalytic performance of ZnFe 2 O 4 due to the abundant units of phenolic groups in tannin molecules. ZnFe 2 O 4 makes the Tannin/ZnFe 2 O 4 /ZnO magnetically separable in a system. This work presents new insights that tannin molecules function as great modifier to improve very impactful tannin-modified magnetic photocatalysts in removing environmental contamination. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of organic dyes in wastewater using visible light illumination is a green technology which requires efficient visible-light driven active catalytic material. For this, we have reported a novel visible light active Eu/WO 3 system with variation in europium contents (0, 2%, 4% and 6% Eu), which demonstrated enhanced photocatalytic activity for the degradation of various organic dyes including methylene blue (MB), methyl orange ((MO) and rhodamine B (RhB). Scanning electron microscopy (SEM), X-ray diffractometer (XRD), energy dispersive X-ray (EDX), UV–visible spectroscopy and photoluminescence (PL) spectroscopy were used for the characterization of nanostructures. The results showed that Eu has effective role in modifying the structural, morphological and optical properties of WO 3 photocatalyst. Moreover, the photocatalytic performance of WO 3 was improved due to incorporation of Eu. From results, it was seen that photocatalytic activity increases with increasing Eu concentration upto 4%, however, further increase in Eu concentration (6%) has decreased the performance under these condition for all dyes. The enhanced photocatalytic efficiency could be attributed to suppressed recombination of charge carriers and enhanced visible light absorption and increased BET surface area due to Eu doping into WO 3 photocatalyst. The as-synthesized nanostructures will be considered as a promising photocatalytic materials for the future research in this field. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a facile way of fabricating visible-light-active lanthanum and nitrogen – co-doped SrTiO 3 – TiO 2 heterostructured macroporous monolithic materials with bicontinuous morphology by impregnating strontium and lanthanum ions into a preformed porous TiO 2 gel in aqeuous solution containing urea followed by heat treatment in NH 3 atmosphere. The SrTiO 3 macroporous monolithic materials were formed by a solid-state reaction between the TiO 2 gel phase and precipitated SrCO 3 , while Sr 2+ was partially substituted with La 3+ ions. The SrCO 3 was precipitated within the TiO 2 wet gel by the reaction between impregnated Sr 2+ and CO 2 , which was produced by hydrolysis and decarbonation of a chelating agent in the TiO 2 wet gels and by hydrolysis of urea at 60 °C. X-ray powder diffraction studies showed that the incorporation of strontium, lanthanum, and nitrogen could effectively retard the phase transformation of TiO 2 from anatase to rutile and growth of crystallites. XPS analysis confirmed that lanthanum atoms were incorporated into the SrTiO 3 lattice by substituting strontium atoms, and nitrogen was incorporated in the TiO 2 lattice (i) substitutionally forming Ti – N-bonds and (ii) interstitially. The resultant lanthanum and nitrogen – co-doped SrTiO 3 - TiO 2 heterostructured monolithic materials retained a narrow macropore size distribution at the diameter ∼1.7 μ m. [ABSTRACT FROM AUTHOR]

Selective functionalization of C(sp 3 ) H bonds is one of the final frontiers of synthetic chemistry. The employment of organic dyes (ODs) as visible light photocatalysts to approach these reactions has been of current interest mainly due to their lower cost and the avoidance of toxic heavy metals. In this digest, we outline the recent advances in organic dye-catalyzed C(sp 3 ) H functionalization reactions. [ABSTRACT FROM AUTHOR]

The present work demonstrates a facile hydrothermal synthesis of Plasmonic Au–TiO 2 nanocatalyst followed by its successful application for complete photocatalytic dye degradation (oxidation) in batch and continuous flow process under natural sunlight as well as visible and UV light. The Au-TiO 2 nanocatalyst was synthesized by a hydrothermal method at basic pH conditions. It was meticulously analyzed by a variety of spectroscopic (UV-Vis, Raman, FTIR, PL, Powder XRD, ED-XRF, XPS), microscopic (FE-SEM with elemental mapping, TEM), and thermal (DSC) techniques. The characterization results showed that monodisperse Plasmonic Au(0) nanoparticles with a mean diameter of 12 ± 1 nm are homogeneously deposited on Anatase TiO 2 crystals. The nanocatalyst showed complete photocatalytic degradation of various dye compounds (Eosin Yellowish, Indigo Carmine, Methyl Orange, Methylene Blue, and Rhodamine B) under visible light or sunlight as confirmed through UV-Vis spectra, mass spectral study, and TOC analysis of dye solutions. A continuous flow process using a specially designed photoreactor was accomplished with a long catalyst lifespan, easy processibility, and low cost. Easy synthesis of the catalyst, its very detailed characterization, and its efficient catalytic studies to completely degrade various dye molecules under visible light source in the absence of any added oxidizer (O 2 , H 2 O 2 , KMnO 4 , Organic peroxides) and the demonstration of continuous flow process are significant highlights of the present work. A plausible mechanistic pathway is also presented in line with the previous literature reports and presently observed phenomenon. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrospun cellulose acetate (CA) membrane was employed as a support that provided sites for AgCl crystals in situ growth. The Ag@AgCl crystals on electrospun CA composites with exposed {1 0 0} and {1 1 1} facets were fabricated at room temperature by a double diffusion technique. The crystal structure, morphology, composition, and absorption light ability of CA supported Ag@AgCl were characterized utilizing X-ray powder diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflection-infrared intensity (ATR-IR), X-ray photoelectron spectroscopy measurements (XPS), energy dispersive spectrometer (EDS) and ultraviolet–visible (UV–vis) diffuse reflectance spectra, respectively. The photocatalytic activity of the catalysts was evaluated using methyl orange (MO) as a target. The CA supported cubic Ag@AgCl catalyst exhibited much higher catalytic activity than octahedral catalyst in terms of the degradation of MO under visible light. The 10 mg CA based cubes could completely degrade MO (10 mg L −1 ) in 160 min. The photocatalyst still exhibited a good catalytic ability after three times. [ABSTRACT FROM AUTHOR]

A hybrid polyoxometalate-aminoazobenzene dye compound, (C 12 H 12 N 3 ) 3 PW 12 O 40 2CH 3 CN ( 1 ) has been synthesized in CH 3 CN/H 2 O solution under conventional reaction conditions. The structure of 1 was determined by single-crystal X-ray diffraction, and further characterized by IR spectroscopy, UV–vis spectra and diffuse reflectance spectra. The absorption edge of 1 is largely red-shifted compared to the pure polyoxoanions, due to the introduction of the dye cations. Photocatalytic studies indicated that compound 1 exhibits effective photocatalytic H 2 evolution activity under visible-light. [ABSTRACT FROM AUTHOR]

In order to improve the catalytic efficiency of titanium dioxide (TiO 2) under visible light, TiO 2 nanoparticles was composed with the silver-covered carbon nanotubes (CA) to form CNTs-Ag-TiO 2 (CAT) ternary structure via in situ reduction combined with sol-gel method. The composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. Using methylene blue (MB) as the model pollutant, photocatalytic activity of CAT was studied to investigate the influence of the composited amount of CA on the effect of photocatalysis. The results revealed that the photocatalytic activity of TiO 2 under both visible light and UV light were improved by compositing with CA. When the mass ratio of CA is 15%, the degradation rare of methylene blue (MB) by CAT reached to 80.8% under visible light in 3 h, which is 16.5 times higher than that of TiO 2. Accordingly, the degradation rate reached to 99.2% under UV light in 40 min, which is nearly twice as fast as that of TiO 2. Image 1 • Research Highlights: • A facile procedure based on in-situ reduction method was developed to synthesize a uniformly coated CNTs-Ag-TiO 2 (CAT) ternary structure. • Ag nanoparticles were constructed between CNTs and TiO 2 and served as a "bridge" in the CAT ternary structure, which exhibited an enhanced photocatalytic performance under visible light. • The detailed mechanism of silver as an intermediate layer has been clearly expounded based on the obviously improved photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

• Facile synthesis of MoS 2 nanostructures. • Decease in size of SnO 2 nanoparticles when synthesized over MoS 2. • Excellent narrow optical band gap for SnO 2 -MoS 2 composites. • Composite nanostructures show enhanced photo-catalytic degradation of Methylene Blue and Methyl Red. • With increase in concentration of SnO 2 on MoS 2 there is enhancement in efficiency. We synthesize semiconductor hybrid nanostructures comprising SnO 2 nanoparticles stacked with two dimensional MoS 2 nanostructures by superficial two-step methodology. The A 1g /E1 2g peak intensity ratio from Raman spectra reveals the type of doping and its effect on chemical structure. SnO 2 nanoparticles in SnO 2 -MoS 2 nanostructures (NSs) decrease the recombination rate of electron-hole pairs of the photocatalyst. We find that: (i) For pristine SnO 2 , the degradation efficiencies in 120 min are 33.8% and 19.9% for Methylene Blue (MB) and Methyl Red (MR), respectively. (ii) For pristine MoS 2 , the degradation efficiencies in 120 min are 34.6% and 36.7% for MB and MR, respectively. (iii) For SnO 2 -MoS 2 nanostructures, the degradation efficiencies in 120 min are enhanced to 58.5% and 94% for MB and MR, respectively. [ABSTRACT FROM AUTHOR]