Aamna Balouch

ZnO nanocubes with (1 0 1) basal plane photocatalyst prepared via a low-frequency ultrasonic assisted hydrolysis process

The crystallographic plane of the ZnO nanocrystals photocatalyst is considered as a key parameter for an effective photocatalysis, photoelectrochemical reaction and photosensitivity. In this paper, we report a simple method for the synthesis of a new (101) high-energy plane bounded ZnO nanocubes photocatalyst directly on the FTO surface, using a seed-mediated ultrasonic assisted hydrolysis process. In the typical procedure, high-density nanocubes and quasi-nanocubes can be grown on the substrate surface from a solution containing equimolar (0.04 M) zinc nitrate hydrate and hexamine. ZnO nanocubes, with average edge-length of ca. 50 nm, can be obtained on the surface in as quickly as 10 min. The heterogeneous photocatalytic property of the sample has been examined in the photodegradation of methyl orange (MO) by UV light irradiation. It was found that the ZnO nanocubes exhibit excellent catalytic and photocatalytic properties and demonstrate the photodegradation efficiency as high as 5.7 percent/μg mW. This is 200 times higher than those reported results using a relatively low-powered polychromatic UV light source (4 mW). The mechanism of ZnO nanocube formation using the present approach is discussed. The new-synthesized ZnO nanocubes with a unique (101) basal plane also find potential application in photoelectrochemical devices and sensing.

Efficient heterogeneous catalytic hydrogenation of acetone to isopropanol on semihollow and porous palladium nanocatalyst.

Highly efficient and remarkable selective acetone conversion to isopropanol has been achieved via a heterogeneous catalytic hydrogenation of acetone by NaBH4 in the presence of semihollow palladium nanoparticles (PdNPs) grown on ITO substrate. PdNPs with high surface defect grown on an indium tin oxide (ITO) surface were prepared via a simple immersion of the substrate into a solution containing K2PdCl6, sodium dodecyl sulphate (SDS), and formic acid for 2 h at room temperature. The sample showed remarkably high heterogeneous catalytic efficiency by producing 99.8% of isopropanol within 6 min using only 0.28 μg of PdNPs on the ITO surface. The present system exhibits heterogenenous catalytic hydrogenation efficiency 1 × 10(6) time higher than using the conventional Raney Ni system.

Ag–ZnO Nanoreactor Grown on FTO Substrate Exhibiting High Heterogeneous Photocatalytic Efficiency

This Research Article reports an unusually high efficiency heterogeneous photodegradation of methyl orange (MO) in the presence of Ag nanoparticle-loaded ZnO quasi-nanotube or nanoreactor (A-ZNRs) nanocatalyst grown on FTO substrate. In typical process, photodegradation efficiency of as high as 21.6% per μg per Watts of used catalyst and UV power can be normally obtained within only a 60-min reaction time from this system, which is 10(3) order higher than the reported results. This is equivalent to the turnover frequency of 360 mol mol(-1) h(-1). High-density hexagonal A-ZNRs catalysts were grown directly on FTO substrate via a seed-mediated microwave-assisted hydrolysis growth process utilizing Ag nanoparticle of approximately 3 nm in size as nanoseed and mixture aqueous solution of Zn(NO3)·6H2O, hexamethylenetetramine (HMT), and AgNO3 as the growth solution. A-ZNRs adopts hexagonal cross-section morphology with the inner surface of the reactor characterized by a rough and rugged structure. Transmission electron microscopy imaging shows the Ag nanoparticle grows interstitially in the ZnO nanoreactor structure. The high photocatalytic property of the A-ZNRs is associated with the highly active of inner sides surface of A-ZNRs and the oxidizing effect of Ag nanoparticle. The growth mechanism as well as the mechanism of the enhanced-photocatalytic performance of the A-ZNRs will be discussed.

Selective heterogeneous catalytic hydrogenation of ketone (C═O) to alcohol (OH) by magnetite nanoparticles following Langmuir-Hinshelwood kinetic approach.

Magnetite nanoparticles were successfully synthesized and effectively employed as heterogeneous catalyst for hydrogenation of ketone moiety to alcohol moiety by NaBH4 under the microwave radiation process. The improvement was achieved in percent recovery of isopropyl alcohol by varying and optimizing reaction time, power of microwave radiations and amount of catalyst. The catalytic study revealed that acetone would be converted into isopropyl alcohol (IPA) with 99.5% yield in short period of reaction time, using 10 μg of magnetite NPs (Fe3O4). It was observed that the catalytic hydrogenation reaction, followed second-order of reaction and the Langmuir-Hinshelwood kinetic mechanism, which elucidated that both reactants get adsorb onto the surface of silica coated magnetite nanocatalyst to react. Consequently, the rate-determining step was the surface reaction of acetone and sodium borohydride. The current study revealed an environment friendly conversion of acetone to IPA on the basis of its fast, efficient, and highly economical method of utilization of microwave irradiation process and easy catalyst recovery.

Highly-reactive AgPt nanofern composed of {001}-faceted nanopyramidal spikes for enhanced heterogeneous photocatalysis application

The structure and property of the catalyst surface determine the physico-chemical process and the reactivity at the surface, such as catalysis behavior, adsorption, surface segregation and charge transfer, etc. A catalyst with a surface containing high-energy facets, high defect or high-energy sites, such as twinning, vertexes, spikes, etc., may facilitate enhanced catalytic and surface reactivity. Here, we present a straightforward approach to synthesize novel nanopyramidal spike composed nanoferns of AgPt bimetals vertically-oriented on the substrate surface for potential application in catalysis. High-resolution transmission electron microscopy analysis reveals that the nanopyramidal spike is characterized by {001} faces, the high-energy facet of the fcc metal system, promising enhanced catalytic reaction. The crystal growth analysis result determines that the lattice-mismatching effect between Ag and Pt is the key factor for the formation of the nanopyramidal AgPt structure and the nanofern suprastructure is produced via oriented-attachment of the nanopyramidals. The heterogeneous catalytic properties characterisation of AgPt nanofern in the photodegradation of methyl orange in the absence of any reducing agent revealed that the catalytic efficiency is determined by the Ag concentration in the nanocrystals and the morphology of the nanofern structure.

Tannic Acid Assisted Copper Oxide Nanoglobules for Sensitive Electrochemical Detection of Bisphenol A

ABSTRACT This study describes the development of an electrochemical sensor system for the determination of bisphenol A using tannic acid functionalized CuO nanoglobules. The utilized tannic acid acted simultaneously as both bio-compatible template and functionalizing agent for the as-synthesised CuO nanostructures. The excellent synergy of high surface area and favorable interactions between the moieties of tannic acid and bisphenol A molecules enabled sensitive electrochemical oxidation of bisphenol A within wide detection window (0.1–5.5 µM) and limit of detection estimated to be 0.01 µM. Moreover, the sensor exhibited satisfactory stability and strong anti-interference capability when evaluated against common interferents molecules such as phenol, hydroquinone, and 4-nitrophenol.

Synthesis of amorphous platinum nanofibers directly on an ITO substrate and its heterogeneous catalytic hydrogenation characterization

This paper reports a facile, solution-phase approach to synthesizing a one-dimensional amorphous face-centered-cubic (fcc) platinum (a-Pt) nanostructure (nanofibers) directly on an indium-tin oxide (ITO) substrate. The electron microscopy analysis result shows that the a-Pt nanofiber has a diameter and length of approximately 50 nm and 1 μm, respectively, and is grown in high density on the entire surface of the ITO substrate. The X-ray photoelectron spectroscopy analysis result further reveals that the a-Pt nanofibers feature metallic properties with highly reactive surface chemistry, promising novel performance in electrochemistry, catalysis, and sensors. A synergetic interplay between the formic acid reducing agent and the hexamethylenetetramine surfactant in the reduction of Pt ions is assumed as the driving force for the formation of the amorphous phase in the Pt nanostructure. The catalytic properties of a-Pt were examined in the acetone hydrogenation reaction under microwave irradiation. a-Pt shows excellent heterogeneous catalytic properties for converting acetone to isopropyl alcohol with turnover number and frequency as high as 400 and 140 min(-1), respectively. The preparation and formation mechanism of the a-Pt nanofibers will be discussed in detail in this paper.

Sensitive fluorescence detection of Ni2+ ions using fluorescein functionalized Fe3O4 nanoparticles

This study describes a very sensitive fluorescence sensor for the selective nanomolar detection of Ni2+ ions. The Ni2+ ion sensing is based on fluorescence quenching of the fluorophore (fluorescein) in neutral aqueous medium. The fluorescence sensor is composed of a magnetic core and amino silica shell, functionalized with a fluorescein fluorophore. The morphology, physical and chemical properties of the sensing materials were studied by FT-IR spectroscopy, X-ray powder diffraction, vibrating sample magnetometer (VSM) and Transmission Electron Microscopy (TEM). UV-visible and fluorescence spectroscopy were used to characterize the fluorescein functionalized magnetic nanoparticles. The characterization measurements revealed that the fluorescent nanostructures were superparamagnetic in nature with an average particle diameter of 10 nm. The as-fabricated fluorescent nanosensor (Fe3O4@SiO2-NH2-fluorescein) showed an enhanced fluorescence quenching response towards Ni2+ ions in neutral pH medium. The response of the nanosensor was highly selective towards the target species whereas the possible interferences from other metal cations and biological molecules were negligible. The fluorescein probe has a very fast response, it is selective and has a sensitive detection limit (LOD = 0.83 nM) towards Ni2+ ions in neutral medium with a high binding constant (K) value of 3.2 × 104 M−1 for the complex formation between the sensor and Ni2+ ions. These features ensure the potential use of fluorescein functionalized magnetic nanomaterials as a new class of non-toxic biocompatible sensors for biological and environmental applications.

Deposition of Au/TiO2 nanocomposite on ITO surface by seed-mediated liquid phase deposition method

An efficient, simple and new procedure has been performed to synthesis Au/TiO2 nanocomposite thin film on solid surface of ITO by seed-mediated of liquid phase deposition (LPD) method. The deposition of Au seed was applied by our previously reported seed-mediated growth procedure. The solution was prepared by mixing HAuCl4 and (NH4)2TiF6 successfully deposited on to ITO substrate containing Au seed. After one hour well adhered film was obtained by mentioned approach of synthesis and nonocomposite with spherical rod like networks has been successfully grown. The resulting nanocomposites were confirmed by ultraviolet-visible (Uv-Vis) absorption spectroscopy. Further characterization and morphology was checked by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD).

Utilization of Pleurotus eryngii biosorbent as an environmental bioremedy for the decontamination of trace cadmium(II) ions from water system

In many parts of the world, cadmium metal concentration in drinking water is higher than some international guideline values. To reduce its level below the safety limit, a sustainable and environmental friendly approach is crucial. Thereby, present article introduce an efficient, non-pathogenic and a novel fungal biosorbent Pleurotus eryngii for the removal of Cd(II) ions from aqueous system. The efficiency of P. eryngii were improved and optimized by investigating many significant factors such as; pH, biosorbent dose, initial Cd(II) ion concentration, temperature and contact time. Maximum Cd(II) ions removal (99.9%) was achieved at pH 5.0, biosorbent dosage 0.2 g/10 mL, concentration 20 mg L-1, time 10 min and temperature 50 °C. The isotherm and kinetic models revealed bioremediation of Cd(II) ions as monolayer coverage with biosorption capacity of 1.51 mg g-1 following pseudo second order reaction. Moreover, thermodynamic parameters such as ΔG°, ΔH°, and ΔS° showed that the removal of Cd(II) ions is spontaneous and endothermic in nature. Batch elution process revealed that the complete elution of Cd(II) ions from the biomass were achieved using 0.1 N HNO3 solution. The sorption efficiency decreased from 99.99 to 56.89% as the biomass were recycled up to five times. The efficiency of Cd(II) ions removal from real water samples lies between 85 and 90%. Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopic (EDS) and atomic force microscopic (AFM) analysis of fungal biomass confirmed that the Cd(II) ions were the most abundant species on the biomass surface after the sorption process.