Decoration of ZnO surface with tiny sulfide-based nanoparticles for improve photocatalytic degradation efficiency.

Modifying wide band gap ZnO nanoparticles surface by combine narrow bandgap semiconductors is a novel route to promote the ZnO to diverse applications. Herein, different metal sulfides (CdS, Ag2S and Bi2S3) were decorated on ZnO surface using facile a chemical route for photocatalytic application. Crystal structure, surface morphology and optical changes for the surface modified ZnO were studied by using various characterization techniques. The XRD spectra exhibited mixed phase of decorated metal sulfide nanoparticles along with strong pattens of hexagonal structure ZnO. The SEM images were confirmed that tiny CdS, Ag2S and Bi2S3 sulfide nanoparticles are well decorated on ZnO hexagonal rods surface. Band gap of the ZnO was tuned into visible region by modifying the surface by the sulfide nanoparticles. Textile industry-based crystal violet (CV) dye was used as a model pollutant to evaluate the photocatalytic activity of sulfides decorated well-crystalline ZnO photocatalysts under natural sunlight. Among the three catalysts, the Ag2S decorated ZnO achieved greatest photodegradation efficiency of 94.1% for degradation of the CV dye with rate constant value of 0.050. The highest catalytic activity may be related to Ag2S acting a significant part in reducing bandgap and boosting hole, superoxide radical, and hydroxyl radical formation, which inhibits recombination, hence enhancing the photocatalyst's efficacy, activity, and also stability.

Synthesis of Acid Free Benzaldehyde by Highly Selective Oxidation of Benzyl Alcohol Over Recyclable Supported Palladium Catalyst.

AIM AND OBJECTIVES: This research work deals with the highly selective oxidation of benzyl alcohol to benzaldehyde by palladium doped graphene oxide catalyst, which was synthesized by a modified Hummer's method. The effect of reaction parameters like temperature, time and catalyst loading were studied. It was found that fine-tuning of reaction temperature and presence of a small amount of benzyl alcohol in a product prevented the undesirable formation of benzoic acid crystals, which form on auto-oxidation of benzaldehyde. Benzoic acid or substituted benzoic acid formation was hindered by the presence of < 2% benzyl alcohol at a reaction temperature of 50˚C, which was further supported by palladium doped graphene oxide catalyst. MATERIALS AND METHODS: Modified Hummer's method was used for the synthesis of graphene oxide and palladium doped graphene oxide was synthesized by in-situ method in which graphene oxide dispersed in 20mL of distilled water was ultrasonicated for 2h. Palladium solution was added and it was further ultrasonicated for 30min for homogeneous deposition of palladium on a graphene oxide support. To this, 2 mL of sodium borohydride solution was added and stirred at room temperature for 4h. The resulting solution was centrifuged, and the residue was dried at 60°C for 12 h. RESULTS: The morphological characteristics and the functional groups of supported catalysts were characterized by X-ray diffraction, Field emission scanning spectroscopy, and Fourier transform infrared spectroscopy. The produced benzaldehyde was characterized by gas chromatography. CONCLUSION: PdGO catalyst was prepared using sodium borohydride as a reducing agent by modified Hummer's method and utilized for the oxidation of benzyl alcohol to benzaldehyde. A maximum conversion of 89% and selectivity of 99% were obtained and the catalyst could be reused up to five times without any compromise on conversion and selectivity.

One-pot Synthesis of ß-acetamido-ß-(phenyl) Propiophenone using ZnO/Carbon Nanocomposites.

AIM AND OBJECTIVES: The focus of the present work is to synthesize ZnO/C composite using dextrose as carbon source by combustion method and study the comparative evaluation on one-pot synthesis of ß-acetamido- ß-(phenyl) propiophenone over ZnO nanoparticles and ZnO/C composite catalyst. MATERIALS AND METHODS: The ZnO nanoparticles has been synthesized by sol-gel method using zinc nitrate and NaOH and ZnO/Carbon composites by combustion method using zinc nitrate and dextrose as carbon source. The resulting gel was placed in a preheated muffle furnace at 400oC. The solution boils and ignites with a flame. On cooling highly amorphous powder of ZnO/Carbon composite is obtained. RESULTS: The XRD patterns reveal the hexagonal phase with Wurtzite structure and the nanocrystalline nature of the catalysts. The SEM image of ZnO/C composite showed that it contains spherical particles with an average size of 41 nm. The average particle size of the composite was around 60nm by DLS method. The catalytic activity of the ZnO/Carbon composites has been analyzed by one-pot four-component condensation of benzaldehyde, acetophenone, acetyl chloride and acetonitrile. The feed molar ratio of 1:1 (Bz:AP) and catalyst loading of 30 mol% is found to be the optimal condition for ß-acetamido ketone conversion over ZnO/carbon composite. CONCLUSION: The substantial catalytic activity of the synthesized ZnO/C composite materials was tested by one-pot four-component condensation of benzaldehyde (Bz), acetophenone (AP), acetyl chloride (AC) and acetonitrile (AN) which showed a high ß-acetamido ketone conversion under the optimized reaction conditions. It has also been found that the catalyst is very stable and reusable.

A facile synthesis of metal ferrites and their catalytic removal of toxic nitro-organic pollutants.

Nitrocompounds are the major prime water contaminants. In this investigative study, toxic nitrocompounds (4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol) were removed by using magnetic CuFe2O4, CoFe2O4, and NiFe2O4 material systems. The metal ferrites were synthesized through hydrothermal method and also followed with calcination process. The properties of metal ferrites were confirmed through using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM) studies and results there on were presented. For the first time, the synthesized CuFe2O4, CoFe2O4, and NiFe2O4 material systems were used for the reduction of 4-nitrophenol (NP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP) in aqueous medium. The UV-visible spectrometry was employed to monitor the removal of nitro compounds and formation of aminophenol. Among, the three catalysts, the CuFe2O4 displayed excellent removal activity for nitrocompounds. The CuFe2O4 nanoparticles completely removed the NP, DNP and TNP within 2, 5, 10 min, respectively. The NP reduction reaction follows the pseudo-first-order kinetics. Further, the investigated and proposed CuFe2O4, catalyst has given and demonstrated excellent kinetic rate constants 0.990, 0.317, 0.184 min-1 for 4-NP, DNP and TNP respectively, which was very fast kinetic than the already published reports. Also, the aminophenol formation was confirmed for the above mentioned and select nitrocompounds. The obtained results confirm suggest that CuFe2O4 nanoparticles based material system could be one of the promising catalysts for nitro compounds removal process.

Surface-tuned hierarchical ɤ-Fe2O3-N-rGO nanohydrogel for efficient catalytic removal and electrochemical sensing of toxic nitro compounds.

4- Nitrophenol (4-NP) is a top rated hazardous environmental pollutant and secondary explosive chemicals. For the sake of ecology and environment safety, the catalytic reduction and detection of 4-NP is highly important. In this work, ɤ-Fe2O3-nitrogen doped rGO (ɤ-Fe2O3-N-rGO) nanohydrogel was synthesized by green hydrothermal method. The morphology and phase purity of prepared ɤ-Fe2O3-N-rGO nanohydrogel were confirmed by various analytical (SEM, TEM, XRD, and XPS) and electrochemical techniques. The morphological structure of ɤ-Fe2O3-N-rGO nanohydrogel confirmed that the nanocrystals are well covered over the 2D N-rGO layer. Further, ɤ-Fe2O3-N-rGO nanohydrogel was applied for the catalytic reduction and electrochemical detection of ecotoxic 4-NP. A low cost, ɤ-Fe2O3-N-rGO nanohydrogel displayed an excellent catalytic activity, high recyclability (>5 cycles) and high conversion efficiency of 4-NP to 4-Aminophenol (4-AP). In addition, ɤ-Fe2O3-N-rGO nanohydrogel modified GCE displayed a wide linear sensing range (0.1-1000 µM), and a low detection limit (LOD) of 0.1 µM with excellent sensitivity, high selectivity (<1.2%) and good stability (>4 weeks). The developed sensor electrode shows the low reduction potential of -0.3 V and -0.60 V for the determination of 4-NP. The proposed ɤ-Fe2O3-N-rGO nanohydrogel is promising catalyst for the detection and removal of toxic aromatic nitro compounds in real site applications.

A review on ZnO nanostructured materials: energy, environmental and biological applications.

Zinc oxide (ZnO) is an adaptable material that has distinctive properties, such as high-sensitivity, large specific area, non-toxicity, good compatibility and a high isoelectric point, which favours it to be considered with a few exceptions. It is the most desirable group of nanostructure as far as both structure and properties. The unique and tuneable properties of nanostructured ZnO shows excellent stability in chemically as well as thermally stable n-type semiconducting material with wide applications such as in luminescent material, supercapacitors, battery, solar cells, photocatalysis, biosensors, biomedical and biological applications in the form of bulk crystal, thin film and pellets. The nanosized materials exhibit higher dissolution rates as well as higher solubility when compared to the bulk materials. This review significantly focused on the current improvement in ZnO-based nanomaterials/composites/doped materials for the application in the field of energy storage and conversion devices and biological applications. Special deliberation has been paid on supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, biomedical and biological applications. Finally, the benefits of ZnO-based materials for the utilizations in the field of energy and biological sciences are moreover consistently analysed.

Synthesis and characterization of ZnO nanoflakes anchored carbon nanoplates for antioxidant and anticancer activity in MCF7 cell lines.

ZnO nanoparticles with flakes-like structures were synthesized by simple wet chemical route using triethanolamine as a mild base. The well distributed ZnO nanoflakes onto carbon nanoplates (ZnO/C) were prepared by wet impregnation method. The crystalline structure and purity of the synthesized samples was inspected using XRD. The shape, structural morphology and elemental composition analysis was studied using FESEM and EDS. The probable anticancer activity of the synthesized samples was studied through their activity on human breast cancer MCF7 cell line. Exposure of breast cancer cells to ZnO and ZnO/C resulted in a dose dependent loss of cell viability, and the characteristic apoptotic features such as early and late apoptosis by dual staining. The results exhibited an enhanced antioxidant activity in the ZnO/C treated cells. This present study demonstrated that the ZnO and ZnO/C can be suggested as compounds with potential activity to induce apoptosis probable anticancer activity agents.