Nanocatalysis

Magnetite (Fe3O4)-supported molybdenum oxide (MoO3) was synthesized from simple starting precursors in aqueous medium. The synthesized nanocat-Fe-Mo was analyzed using several techniques such as X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating-sample magnetometry (VSM). The catalytic activity of the synthesized nanocat-Fe-Mo was studied in a benign one-pot multicomponent transformation for synthesis of amidoalkyl naphthol derivatives under solventfree condition using both conventional and microwave irradiation methods. Nanocat-Fe- Mo was found to be highly active and could be reused seven times without notable loss in catalytic activity. The proposed method offers advantages such as good reaction yield (80–95%), short process time, simple workup, and recycling of the catalyst, representing important green chemistry principles.

Scope & Topics Nanoscience and Technology: An International Journal (NTIJ) is a peer-reviewed, open access journal, addresses the impacts and challenges of Nanoscience and Technology. The journal documents practical and theoretical results which make a fundamental contribution for the development of Nanoscience and Technology. This journal aims to bring together researchers and practitioners in all Nano aspects, including (but not limited to): Topics Of Intrested: ■ Micro / Nano Fabrication and Metrology ■ Micro / Nano Heat Transfer and Energy Information Technology, ■ Micro / Nano Sensors , Actuators and Systems Nanobionics ■ Micro / Nanofluidics and Bio Chips ■

12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impreg-nation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N 2 adsorption-desorption at −196 • C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively , examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 • C shows the highest acidity and catalytic activity.

Abstract Magnetite (Fe3O4)-supported molybdenum oxide (MoO3) was synthesized
from simple starting precursors in aqueous medium. The synthesized nanocat-Fe-Mo
was analyzed using several techniques such as X-ray diffraction (XRD) analysis, X-ray
photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission
electron microscopy (TEM), and vibrating-sample magnetometry (VSM). The catalytic
activity of the synthesized nanocat-Fe-Mo was studied in a benign one-pot multicomponent
transformation for synthesis of amidoalkyl naphthol derivatives under solventfree
condition using both conventional and microwave irradiation methods. Nanocat-Fe-
Mo was found to be highly active and could be reused seven times without notable loss
in catalytic activity. The proposed method offers advantages such as good reaction yield
(80–95%), short process time, simple workup, and recycling of the catalyst, representing
important green chemistry principles.

A novel and facile approach for synthesis of zinc oxide (ZnO) nanoparticles (NPs) employing homogeneous chemical precipitation followed by hydrothermal heating technique is reported. The present method of synthesis of ZnO NPs is very efficient and cost effective. As-synthesized ZnO NPs were characterized by XRD, FT-IR, EDX, TEM, and N 2 adsorption–desorption (BET) studies. The powder XRD pattern furnished evidence for the formation of hexagonal close packing structure of ZnO NPs having average crystallite size 21.93 nm. The shapes of synthesized ZnO NPs are mostly quasi-cylindrical with sizes 20–50 nm. These ZnO NPs were used as catalysts for the degradation of a pharmaceuticals waste, metronidazole under ultrasound irradiation.

A wet chemical preparation of MgO with the (111) facet as the primary surface has recently been reported and with alternating layers of oxygen anions and magnesium cations, this material shows unique chemical and physical properties. The potential to utilize the MgO(111) surface for the immobilization of metal particles is intriguing because the surface itself offers a very different environment for the metal particle with an all oxygen interface, as opposed to the typical (100) facet that possesses alternating oxygen anion and magnesium cation sites on the surface. Gold nanoparticles have demonstrated a broad range of interesting catalytic properties, but are often susceptible to aggregation at high temperatures and are very sensitive to substrate effects. Here, we investigate gold-supported on MgO(111) nanosheets as a catalyst system for the aerobic oxidation of benzyl alcohol. Gold nanoparticles deposited on MgO(111) show an increased level of activity in the solvent-free benzyl alcohol aerobic oxidation as compared to gold nanoparticles deposited on a typical MgO aerogel. TEM studies reveal that the gold nanoparticles have a hemispherical shape while sitting on the main surface of MgO(111) nanosheets, with a large Au–MgO interface. Given that the gold nanoparticles deposited on the two types of MgO have similar size, and that the two types of unmodified MgO show almost the same activities in the blank reaction, we infer that the high activity of Au/MgO(111) is due to the properties of the (111) support and/or those of the gold–support interface. To understand the binding of Au on low-index MgO surfaces and the charge distribution at the surface of the support, we have performed density functional theory (DFT) calculations on all low-index MgO substrates (with and without gold), using a model Au10 cluster. Due to similar lattice constants of Au(111) and MgO(111) planes, the Au cluster retains its structural integrity and binds strongly on MgO(111) with either oxygen or magnesium termination. Furthermore, we have found that for the (001) and (110) substrates the charges of the ions in the top surface layer have similar values as in bulk MgO, but that on (111) surfaces these charges are significantly different. This difference in surface charge determines the direction of the electronic transfer upon adsorption of gold, such transfer occurring so as to restore the bulk MgO charge values. Using the results from theoretical calculations, we provide an explanation of our observations of increased catalytic activity in the case of the Au/MgO(111) system.

The present paper reports on an experiment to improve the productivity of solar still using nano-particles. Solar distillation is a relatively simple treatment of brackish or impure water. In this solar energy is used to evaporate water then this vapour is condensed as pure water. This process removes salts and other impurities. Latest trend to improve the efficiency of the solar still is use of nano-particles like metal oxides. These particles increase surface area of absorption to solar radiation. In this work the Al2O3 nanoparticles mixed black paint is used to enhance the productivity of solar still. The solar radiations are transmitted through the glass cover and captured by a black painted inner bottom surface of the solar still. Water absorbs the heat and is converted into vapour within the chamber of the solar still.Single slop solar still is used from past decades but in this study effect of nano-particles on productivity of solar still is analyzed. Experimental work is per...

Second generation biofuels derived from agricultural lignocellulosic waste represent what is hoped to be a significant technological, but also socioeconomic advance beyond the shortcomings of first generation biofuels (chiefly bioethanol). The development of advanced catalytic techniques is a central part of making such technologies viable. However, assessing the potential socioeconomic significance of the socio-technical arrangements necessary to translate such fundamental techniques into mature technologies is also a central part of shaping the development of second generation technologies in a way that both avoids the shortcomings of first generation fuels and ensures that future developments are genuinely responsive to social needs. A pilot project is described in which a deliberative workshop with farmers in Wales is used to explore the potential societal impacts of novel nanocatalysis methods for the production of lignocellulosic biofuels developed by members of the research team. Using risk-and benefit-ranking/issue mapping methodologies, the workshop examined the potential future role of bioeconomies of different scales, in which second generation biofuels play a significant part, in transforming rural communities. Grounded scepticism from workshop participants delineated key socio-technical issues that will be highly consequential for the development of second-generation technologies, thus laying the ground for subsequent planned work on responsible innovation and nanocatalytic methods of biofuel production.

In this work, a Co-Fe-Ni catalyst was prepared and the effect of a range of operational variables such as gas hourly space velocity (GHSV), calcination temperature, calcination time and agent on its catalytic performance for green-fuels production was investigated. By application of different characterization techniques such as XRD, BET, TGA/DSC, and SEM, it was found that these parameters have great effects on the structure, porosity, morphology and physic-chemical properties of this catalyst. The optimum conditions were found for the samples which were calcined at 550 ℃ in air for 6 hours, and operated at 300 ℃ and 4800 h-1 as the reaction temperature and GHSV respectively. Results also revealed that any increase in the calcination temperature promotes the product shifting towards heavier hydrocarbons (more C5+ production). Calcination in air atmosphere was more effective than calcination in N2 atmosphere.

A series of 12-tungstophosphoric acid (TPA) modified SnO 2 samples (TPA-SnO 2) with varying TPA content were prepared by wet impregnation technique. The TPA-SnO 2 catalysts were characterized by thermal analysis, powder X-ray diffraction (XRD) patterns and N 2 adsorption at −196 • C. The surface acidity was measured by potentiometric titration and FTIR spectra of chemically adsorbed pyridine. The DTA shows a peak maximum at 600 • C which was ascribed to the crystallization of tin oxyhydroxide into SnO 2. The thermograms of TPA show no exothermic effect due to the decomposition of TPA up to 25 wt%. When TPA content reached 30 wt% TPA/SnO 2 an exothermic effect at 618 • C indicated that the thermal stability of TPA on SnO 2 seems to be comparable to that of pure TPA. XRD measurements showed that there are no diffraction patterns of TPA for the catalyst calcined at 500 • C. The presence of TPA on tin oxide inhibits sintering of the particles during calcination by reducing the crystallite size of SnO 2 from 27.7 to 19.8 nm. The surface area values increase gradually with increasing TPA loading to reach a maximum limit of 25 wt% TPA. When calcination temperature is increased to 500 • C the specific surface is decreased. The acidity measurements showed that the total acidity increases with the rise of TPA content up to 30 wt%. FTIR spectra of pyridine adsorbed on the catalysts showed the presence of both Bronsted and Lewis acid sites. An optimum reaction performance (78.0% of 7-hydroxy-4-methyl coumarin formed) was achieved at 30 wt% loading of TPA calcined at 400 • C and reaction conditions of 120 • C, 2 h reaction and 1:2 (resorcinol:ethyl acetoacetate) molar ratio.

Nanocrystalline sulfated tin oxide with different sulfate contents (5–30 wt%) were prepared from hydroxylated tin oxide obtained by the precipitation method, followed by wet impregnation with SO42− species using a sulfuric acid solution. In samples calcined at 400, 500 and 600 °C the characterization of the solids was made by DTA, XRD and nitrogen adsorption. The strength and number of acid sites were determined by nonaqueous titration of n-butylamine in acetonitrile. Both Bronsted and Lewis acid sites were determined by FTIR spectra of pyridine adsorbed. Sulfated tin oxides were tested in the synthesis of 7-hydroxy-4-methyl coumarin via solvent free Pechmann reaction of resorcinol:ethylacetoacetate (molar ratio 1:2), at 120 °C. DTA measurements showed that SO42− addition tends to slow down the formation of SnO2 crystallites. XRD profiles showed that the sulfating inhibits the SnO2 crystal growth. The SO4 species remained strongly bonded at the SnO2 surface stabilizing its crystalli...

Nanoscience and Technology: An International Journal (NTIJ) is a peer-reviewed, open access journal, addresses the impacts and challenges of Nanoscience and Technology. The journal documents practical and theoretical results which make a fundamental contribution for the development of Nanoscience and Technology.

Sistemas  catalíticos  de  Cu/t‐ZrO2 y  su  sinergia  representan  nuevas  oportunidades,  en  el  desarrollo  de catalizadores  eficientes  con  excelentes  propiedades  de  óxido‐reducción.  En  este  trabajo  fue  desarrollada una metodología de preparación de catalizadores Cu/ZrO2
‐i, donde el subíndice i representa átomos de Al+3 y  SO4‐2
  que  fueron  incorporados  en  la  preparación  del  soporte.  La  adición  de  la  fase  activa  de  Cu+2   (3%)  se realizó  usando  síntesis  sonoquímica  y  manteniendo  parámetros  fijos  de  energía.  Los  resultados experimentales  mostraron  que  este  método,  permitió  incorporar  el  cobre  en  las  fases  cristalinas  de  la estructura  de  la  ZrO2   dopada;  modificando  su  estructura  después  de  la  calcinación.  El  efecto  de  la  estructura  catalítica  del  soporte  en  el  transporte  de  O2,  permitió  determinar  que  la  adición  de  Al
+3 y  SO4‐2 influencian la capacidad de almacenamiento de O2
 y la naturaleza de los clusters metálicos de cobre.

The present paper reports on an experiment to improve the productivity of solar still using nano-particles. Solar distillation is a relatively simple treatment of brackish or impure water. In this solar energy is used to evaporate water then this vapour is condensed as pure water. This process removes salts and other impurities. Latest trend to improve the efficiency of the solar still is use of nano-particles like metal oxides. These particles increase surface area of absorption to solar radiation. In this work the Al2O3 nanoparticles mixed black paint is used to enhance the productivity of solar still. The solar radiations are transmitted through the glass cover and captured by a black painted inner bottom surface of the solar still. Water absorbs the heat and is converted into vapour within the chamber of the solar still.Single slop solar still is used from past decades but in this study effect of nano-particles on productivity of solar still is analyzed. Experimental work is per...

Gold is often considered the most inert of all metals. In fact, it is a widely held belief instilled in us from the earliest days in our school chemistry laboratories that gold is amongst the most stable and incorruptible of substances. For that reason, its chemical reactivity has not yet been as fully investigated as that of the platinum group

Ligand control of metal nanoparticles (MNPs) is rapidly gaining importance as ligands can stabilize the MNPs and regulate their catalytic properties. Herein we report the first example of Pt NPs ligated by imidazolium-amidinate ligands that bind strongly through the amidinate anion to the platinum surface atoms. The binding was established by (15)N NMR spectroscopy, a precedent for nitrogen ligands on MNPs, and XPS. Both monodentate and bidentate coordination modes were found. DFT showed a high bonding energy of up to -48 kcal mol(-1) for bidentate bonding to two adjacent metal atoms, which decreased to -28 ± 4 kcal mol(-1) for monodentate bonding in the absence of impediments by other ligands. While the surface is densely covered with ligands, both IR and (13)C MAS NMR spectra proved the adsorption of CO on the surface and thus the availability of sites for catalysis. A particle size dependent Knight shift was observed in the (13)C MAS NMR spectra for the atoms that coordinate to t...

Monometallic and bimetallic MOF/MCM-41 composites (Cu, Ag and Cu-Ag) were synthesized via a solvothermal method. The synthesized composites were characterized by XRD, FTIR, SEM, EDX and BET surface area measurements. The acidity was determined through two techniques; potentiometric titration with n-butyl amine for determining the strength and the total number of acid sites and FTIR spectra of chemisorbed pyridine on the surface of MOFs for determining the type of acid sites (Brønsted and/or Lewis). All the prepared MOFs showed Lewis-acid sites and the higher acidity was observed for the bimetallic Cu-Ag MOF/ MCM-41 composite. The catalytic activity was examined on the synthesis of 1-amidoalkyl-2-naphthol via the reaction of benzaldehyde, 2-naphthol and benzamide. The best yield (92.86%) was obtained in the least time (10 min) with a molar ratio 1.2 : 1.2 : 1.7 of benzaldehyde : b-naphthol : benzamide and 0.1 g bimetallic Cu-Ag MOF/MCM-41 composite under solvent-free conditions at 130 C. Reuse of the catalysts showed that they could be used at least four times without any reduction in the catalytic activity.

The mesoporous WO 3 /TiO 2 photocatalysts with different loadings of WO 3 (5, 10 and 15) wt% were used to remove methylene blue (MB) from aqueous solution. The prepared photocatalysts were characterized by XRD, FTIR, BET, SEM and EDX analysis. The XRD showed that the samples 10 and 15 wt% WO 3 /TiO 2 have signals of anatase and rutile phases of TiO 2. FTIR results showed that more hydroxyl groups bind onto the surface of the sample 10 wt% WO 3 /TiO 2 which enhances the photodegradation as they yield OH%. The ultraviolet visible diffuse reflection spectra (DRS) indicated that the addition of WO 3 to TiO 2 decrease the band gap energy from 3.11 to 2.92 eV. The photocatalytic measurements showed that the addition of WO 3 to the surface of TiO 2 increased the photodegradation of MB to 99% after 3 h on the sample 10 wt% WO 3 /TiO 2. Further addition of WO 3 particles agglomerate on TiO 2 surface and decrease the photodegradation. The kinetic studies confirmed that the photocatalytic degradation of MB follows the kinetics of the pseudo-first-order model.

Ligand control of metal nanoparticles (MNPs) is rapidly gaining importance as ligands can stabilize the MNPs and regulate their catalytic properties. Herein we report the first example of Pt NPs ligated by imidazolium-amidinate ligands that bind strongly through the amidinate anion to the platinum surface atoms. The binding was established by 15 N NMR spectroscopy, a precedent for nitrogen ligands on MNPs, and XPS. Both monodentate and bidentate coordination modes were found. DFT showed a high bonding energy of up to À48 kcal mol À1 for bidentate bonding to two adjacent metal atoms, which decreased to À28 AE 4 kcal mol À1 for monodentate bonding in the absence of impediments by other ligands. While the surface is densely covered with ligands, both IR and 13 C MAS NMR spectra proved the adsorption of CO on the surface and thus the availability of sites for catalysis. A particle size dependent Knight shift was observed in the 13 C MAS NMR spectra for the atoms that coordinate to the surface, but for small particles, $1.2 nm, it almost vanished, as theory for MNPs predicts; this had not been experimentally verified before. The Pt NPs were found to be catalysts for the hydrogenation of ketones and a notable ligand effect was observed in the hydrogenation of electron-poor carbonyl groups. The catalytic activity is influenced by remote electron donor/acceptor groups introduced in the aryl-N-substituents of the amidinates; p-anisyl groups on the ligand gave catalysts several times faster the ligand containing p-chlorophenyl groups.

This paper investigates the extent of the self-assembly process of Au
nanoparticles, depending on the nature of structural and functional moieties of
various amino acids (L-cystine, glutathione, L-cysteine and N-acetyl cysteine) and
their influence on the plasmon sensitivity and electrokinetic parameters in correlation
with the catalysis of p-nitrophenol reduction. DLS particle size analysis
revealed that the hydrodynamic size 10–20 nm of Au nanospheres was increased to
135–550 nm, 100–460 nm and 130–240 nm after the addition of L-cystine, L-cysteine
and glutathione, respectively, in contrast to no significant change of particle
size (15–60 nm) after N-acetyl cysteine addition. This difference in the extent of
aggregation as a function of structures of amino acids is further evidenced by
lengthy tubular arrays formation by glutathione as compared to branched chain like
morphology obtained by L-cystine through TEM. FTIR studies further confirmed the
binding of amino acids to Au nanospheres via –SH followed by linking of adjacent
nanoparticles through H-bonding. Due to the conformational diversity of amino
acids, the surface adsorbed –SH, –COO- and –NH3
? species over assembled Au
nanoparticles led to the alteration of zeta potential and conductance, thus affected
the catalysis for the reduction of p-nitrophenol as compared to unmodified Au
nanoparticles.

What to do after VHS tape? Magnetic
nanoparticles are relevant alternatives
to conventional inert supports from
a sustainable chemistry viewpoint. By
using magnetic separation, time-consuming
and tedious filtration/separation/
isolation protocols can be significantly
simplified into a one/two-step
method catalyst recovery and reuse.

MCM-41 anchored sulfonic acid (MCM-41–SO3H) was found to be a highly efficient and recoverable heterogeneous catalyst for the three-component Strecker reaction of aldehydes or ketones and diverse amines using trimethylsilyl cyanide (TMSCN) to afford the corresponding α-amino nitriles under mild conditions in high to quantitative yields. The simple experimental procedure along with easy recovery and reusability of the catalyst has led to development of a clean and environmentally friendly approach for the synthesis of α-amino nitriles.