During
the last two decades, the synthesis of silica with an ordered mesoporous
structure has been thoroughly explored. The basis of the synthesis is to let
silica monomers polymerize in the presence of an amphiphilic template
component. In the first studies, cationic surfactants were used as structure
inducer. Later it was shown that pluronic copolymers also could have the role.
One advantage with the pluronics copolymers is that they allow for a wider
variation in the radius of pores in the resulting silica material. Another
advantage lies in the higher stability resulting from the thicker walls between
the pores. Mesoporous silica has a very high area to volume ratio, and the
ordered structure ensures surface homogeneity. There are a number of
applications of this type of material. It can be used as support for catalysts,
as templates to produces other mesoporous inorganic materials, or in controlled
release applications.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Many
chemical reactions—etching, growth, and catalytic—produce highly faceted
surfaces. Examples range from the atomically flat silicon surfaces produced by
anisotropic etchants to the wide variety of faceted nanoparticles, including
cubes, wires, plates, tetrapods, and more. This faceting is a macroscopic
manifestation of highly site-specific surface reactions. In this Account, we
show that these site-specific reactions literally write a record of their
chemical reactivity in the morphology of the surface—a record that can be
quantified with scanning tunneling microscopy.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Importantly,
the onset of catalysis by the [(PY5Me2)Co(H2O)]2+ series is anodically shifted
by introducing electron-withdrawing functional groups on the ligand. With the
[(bpy2PYMe)Co(CF3SO3)]1+ system, we showed that introducing a redox-active
moiety can facilitate the electro- and photochemical reduction of protons from
weak acids such as acetic acid or water. Using a high-throughput photochemical
reactor, we examined the structure–reactivity relationship of a series of
cobalt(ii) complexes. Taken together, these findings set the stage for the
broader application of polypyridyl systems to catalysis under environmentally
benign aqueous conditions.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Light
is a fascinating phenomenon that ties together physics, chemistry, and biology.
It is unmatched in its ability to confer information with temporal and spatial
precision and has been used to map objects on the scale of tens of nanometers
(10–8 m) to light years (1016 m). This information, gathered through
super-resolution microscopes or space-based telescopes, is ultimately funneled
through the human visual system, which is a miracle in itself. It allows us to
see the Andromeda galaxy at night, an object that is 2.5 million light years
away and very dim, and ski the next day in bright sunlight at an intensity that
is 12 orders of magnitude higher.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Supramolecular
bioinorganic chemistry is a natural evolution in biomimetic metallic systems
since it constitutes a further degree of complexity in modeling. The
traditional approach consisting of mimicking the first coordination sphere of
metal sites proved to be very efficient, because valuable data are extracted
from these examples to gain insight in natural systems mechanisms. But it does
not reproduce several specific aspects of enzymes that can be mimicked by the
implementation of a cavity embedding the labile active site and thus
controlling the properties of the metal ion by noncovalent interactions. This
Account reports on a strategy aimed at reproducing some supramolecular aspects
encountered in the natural systems.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Magnetic
iron oxide nanoparticles have been extensively investigated for their various
biomedical applications including diagnostic imaging, biological sensing, drug,
cell, and gene delivery, and cell tracking. Recent advances in the designed
synthesis and assembly of uniformly sized iron oxide nanoparticles have brought
innovation in the field of nanomedicine. This Account provides a review on the
recent progresses in the controlled synthesis and assembly of uniformly sized
iron oxide nanoparticles for medical applications. In particular, it focuses on
three topics: stringent control of particle size during synthesis via the
“heat-up” process, surface modification for the high stability and
biocompatibility of the nanoparticles for diagnostic purposes, and assembly of
the nanoparticles within polymers or mesoporous silica matrices for theranostic
applications.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Flame
retardants are widely used industrial chemicals that are added to polymers,
such as polyurethane foam, to prevent them from rapidly burning if exposed to a
small flame or a smoldering cigarette. Flame retardants, especially brominated
flame retardants, are added to many polymeric products at percent levels and
are present in most upholstered furniture and mattresses. Most of these
chemicals are so-called “additive” flame retardants and are not chemically
bound to the polymer; thus, they migrate from the polymeric materials into the
environment and into people. As a result, some of these chemicals have become
widespread pollutants, which is a concern given their possible adverse health
effects. Perhaps because of their environmental ubiquity, the most heavily used
group of brominated flame retardants, the polybrominated diphenyl ethers
(PBDEs), was withdrawn from production and use during the 2004–2013 period.
This led to an increasing demand for other flame retardants, including other
brominated aromatics and organophosphate esters. Although little is known about
the use or production volumes of these newer flame retardants, it is evident
that some of these chemicals are also becoming pervasive in the environment and
in humans.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Selective
oxidation reactions have extraordinary value in organic chemistry, ranging from
the conversion of petrochemical feedstocks into industrial chemicals and
polymer precursors to the introduction of heteroatom functional groups into
pharmaceutical and agrochemical intermediates. Molecular oxygen (O2) would be
the ideal oxidant for these transformations. Whereas many commodity-scale
oxidations of simple hydrocarbon feedstocks employ O2 as an oxidant, methods
for selective oxidation of more complex molecules bearing diverse functional
groups are often incompatible with existing aerobic oxidation methods. The
latter limitation provides the basis for our interest in the development of new
catalytic transformations and the elucidation of mechanistic principles that
underlie selective aerobic oxidation reactions. One challenge inherent in such
methods is the incommensurate redox stoichiometry associated with the use of
O2, a four-electron oxidant, in reactions that achieve two-electron oxidation
of organic molecules.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
While
the use of visible light to drive chemical reactivity is of high importance to
the development of environmentally benign chemical transformations, the
concomitant use of a stoichiometric electron donor or acceptor is often
required to steer the desired redox behavior of these systems. The low-cost and
ubiquity of tertiary amine bases has led to their widespread use as reductive
additives in photoredox catalysis. Early use of trialkylamines in this context
was focused on their role as reductive excited state quenchers of the
photocatalyst, which in turn provides a more highly reducing catalytic
intermediate.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
This
Account provides an overview of organic, covalent, porous frameworks and
solid-state materials mainly composed of the elements carbon and nitrogen. The
structures under consideration are rather diverse and cover a wide spectrum.
This Account will summarize current works on the synthetic concepts leading
toward those systems and cover the application side where emphasis is set on
the exploration of those systems as candidates for unusual high-performance
catalysis, electrocatalysis, electrochemical energy storage, and artificial
photosynthesis.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
The
adsorption capacity of riverbed sand, sawdust, vermiculite and soil for Cr
(III) ions from tannery effluent has been investigated in detail in order to
evaluate their possible application as filter material in reed bed treatment
system. The adsorption isotherm was determined along with the effect of contact
time, initial Cr concentration and pH on the efficiency of Cr removal.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
The
change in salinity profile is highly region specific, and is a function of
geophysical set up of the area that undergoes modifications with time.
Therefore, short term scale regional based observations do not allow for a
reliable estimate of the global average change in salinity in the oceans and
adjacent estuaries. The regional picture of climate change induced salinity
profile requires a data of minimum 30 years to conceptualize the cause and
effect of salinity alteration on biotic community.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Thermal
conductivity, thermal diffusivity and specific heat expanded with moisture
content in the above moisture range. Thermal properties were discovered to be
both moisture and bulk density subordinate. Bulk density of Tagetes took after
an illustrative association with moisture content. It was observed that thermal
conductivity, thermal diffusivity and specific heat of Tagetesspecimens were in
the range of 0.989 to 1.564 W/m.k., 11 x 10-8 to 6 x10-8 m2 /s and 5 to 9
kj/kg.k.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
The
biological and medicinal properties of flavonoids have prompted enormous
research aimed at developing synthetic routes to these heterocyles. This review
focuses on the general structures and classification, food sources, medicinal
properties associated with this system. Various synthetic methods developed
till now for these compounds are reviewed, particularly those related to the
synthesis of flavanones, flavones, aurones, isoflavones and flavonols.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Based
on the chlorophyll content and Secchi disc visibility, the Trophic State Index
(TSI) values were calculated for chlorophyll α and Secchi disc visibility
(Carlson method) and for chlorophyll α alone (Walker method). Additional
measurements included the pH, dissolved oxygen, oxygenation and conductivity of
the water. As demonstrated by the analyses conducted in the experiment, the
annual average chlorophyll α content varied from approximately 2.5 ug/L in
oligotrophic reservoirs (such as for example Pogoria III and Kuźnica
Warężyńska), up to more than 70 ug/L in retention reservoirs holding strongly
eutrophicated water (i.e. Rozlewisko Bytomki and Żabie Doły N). Water
transparency ranged from over 5 m in oligotrophic reservoirs (5.1 m in Pogoria
III and 5.5 m in Kuźnica Warężyńska), down to less than 0.5 m in hypertrophic
reservoirs (Kamieniec – 0.35 m and Rozlewisko Bytomki - 0.45 m ). Based on the
calculated TSI indicators and the classifications found in bibliographic
sources covering chlorophyll content, the reservoirs covered by the study were
classified according to their specific trophic type. There were three
reservoirs classified as oligotrophic and eight as mesotrophic water bodies.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Benz(a)Anthracene
in particular, showed a higher degradation rate as compared to the Anthracene.
Photochemical degradation of these PAHs was done with UV radiations (230 &
253 nm) along with TiO2 as catalyst. The best results was obtained with mixed
UV (230 & 253 nm) and visible radiation along with TiO2 as catalyst This
study was carried out in atmospheric conditions (78% Nitrogen and 21% Oxygen
with trace of water vapor, carbon dioxide, argon and various other components
in reaction tube). The maximum degradation in such condition was 63 and 78%
with 8-9 new products.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Bis{tetrakis(5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazinato}
cerium has been prepared for the first time via two alternative synthetic
pathways: template macrocyclization of
5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepine-2,3-dicarbonitrile and direct
complexation employing its cyclic tetramer, a free-base porphyrazine ligand. A
combination of HRMS, UV-Vis, FT-IR and NMR spectroscopic methods allowed the
identification of the tetravalent oxidation state of cerium ion in the
double-decker obtained. Unlike Pc2CeIV (Pc2− = phthalocyaninate anion), the
compound revealed a complicated UV-Vis spectrum that demonstrated a strong solvent
dependence.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Water pollution from arsenic and some other heavy metals has been
reported all over the world. The goal of this investigation is to develop
different polysaccharides–polyvinyl alcohol (PVA) hydrogel graft materials for
the removal of toxic and carcinogenic arsenic (As) species as well as a series
of heavy metals (Mn2+, Cr2+, Fe3+, Ni2+, Cu2+ and Pb2+) from contaminated
water. Hydrogels were developed with PVA and PVA/polysaccharide (as blended
materials) using a γ-ray irradiation technique and then characterized by
Fourier transform infrared (FTIR) and gravimetric methods. The absorbed dose of
γ-radiation was optimized to obtain good gelation, and some important physical
parameters such as gel fraction, degree of swelling and water absorption
kinetics of the synthesized hydrogels were also investigated. The optimum
absorbed dose of 30 kGy gave a gel fraction of about 98% in the PVA/corn starch
(CS) hydrogel. The developed hydrogels have the capability to make chelates,
which are utilized for the removal of arsenic and heavy metals. The absorption
of arsenic and heavy-metal ions from the respective aqueous solution by the
chelating functionalized gels has been assessed by atomic absorption
spectrophotometry (AAS).
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Recently, hopeite coatings on metals, obtained by the zinc phosphate
chemical conversion (ZPCC) process, has attracted increasing attention owing to
their potential biomedical application. The present study focused on the
processing time necessary for the formation of hopeite coatings by the ZPCC
method on stainless steel. It was shown that the coatings were composed of
hopeite with a minor amount of phosphophyllite. Both the coating mass and bath
efficiency reached the highest values after ZPCC treatment at 75 °C for 30 min.
Electrochemical analysis revealed that the coating obtained for 30 min
presented the best corrosion resistance and thus represented the optimum time.
Adhesion tests indicated that the coating was strongly attached on the substrate.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
The conventional methods of Au co-catalyst deposition onto TiO2 surfaces
generally do not offer fine tuning of the metal–TiO2 interface for enhanced
photoactivity because of the non-uniform distribution of the size and shape of
metal nanodeposits. Hence, this study demonstrated the comparative co-catalysis
activity imparted to TiO2 by as-prepared coinage metal (Au, Ag and Cu) quantum
dot particles of similar sizes (3–5 nm) as a function of their plasmonic
interactions with TiO2 under visible light irradiation. The physiochemical and
interfacial properties of metal–TiO2 composites are studied by optical band
gap, XRD, XPS, TEM, surface area, time resolved spectroscopy, current–voltage
characteristics, GC and GC-MS analysis. It was revealed that the optical band
gap is shifted to 2.9 eV from 3.2 eV of bare TiO2 and the specific surface
area, 50 m2 g−1, of TiO2 is notably reduced to 20–33 m2 g−1 after metal
nanoparticles impregnation (M–TiO2) that were found to exist in the Au0 and
Ag0, and Cu+2 oxidation states.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Bi2Sn2O7 photocatalysts were synthesized by a hydrothermal method.
Bi2Sn2O7 photocatalysts showed highly efficient photocatalytic activity for the
degradation of methylene blue under visible light irradiation. Kinetic studies
using radical scavenger technologies suggested that holes were the dominant
photooxidants. After hybridization with C3N4, the photocatalytic activity of
Bi2Sn2O7 was obviously enhanced. The enhanced photocatalytic activity of the
C3N4/Bi2Sn2O7 photocatalysts could be attributed to the effective separation of
the photogenerated e−/h+ pairs. The photogenerated holes on the valence band of
Bi2Sn2O7 can transfer to the highest occupied molecular orbital of C3N4 via the
well developed interface, causing a reduction in the probability of e−/h+
recombination; consequently, large numbers of photogenerated holes led to
enhancing the photocatalytic activity.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
In this report, a new easy-to-synthesize chemosensor, a
(2,4-dinitrophenyl)hydrazine (DNP) derivative of
4-(di(1H-indol-3-yl)methyl)benzaldehyde (hereafter 2a), was designed,
synthesized and employed as a selective optical chemosensor for fluoride
through naked eye detection via patterns of color changes as well as changes in
absorption signals. The binding interaction between 2a and fluoride from 1H NMR,
UV-vis, and density functional studies suggests that fluoride-induced
interaction followed by deprotonation to its corresponding tri-anions is
responsible for the significant color and spectral changes in the absorption
properties of 2a. The ratiometric responses of 2a specifically to fluoride ions
allow us to detect and estimate the concentration of fluoride ions accurately
up to 2 μM.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
A series of white light-emitting hyperbranched copolymers (P2–P5)
consisting of polyfluorene/4,7-dithienyl-2,1,3-benzothiadiazole (DBT) branches
and spiro[3.3]heptane-2,6-dispirofluorene (SDF) conjugated branching point have
been synthesized and fully characterized. The effects of the branching degree
on the thermal, photoluminescent and electroluminescent properties of the
copolymers were investigated. The results suggest that the branching point
helps to enhance both the thermal and spectral stabilities of the hyperbranched
copolymers, and retain the energy transfer efficiency from fluorene to DBT
unit. Efficient hyperbranched copolymer-based single-layer devices are achieved
with CIE coordinates located at near (0.33,0.33). Especially, a device based on
P4 (10 mol% of SDF) exhibits a doubled efficiency and 5.5-fold increase in
luminance compared to the device based on the linear reference.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
The phosphaguanylation reaction of phosphines with carbodiimides
catalyzed by half-sandwich yttrium tris(trimethylsilylmethyl) ate complexes is
achieved for the first time to efficiently prepare phosphaguanidines. The
catalyst system of the yttrium ate complex displays better catalytic activity
than those of neutral yttrium complexes.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
A fluorescent chemosensor was designed and synthesized by incorporating
the imidazolium and 1,8-naphthalimide dye moieties into a preorganized tripodal
receptor. The novel sensor displays high selectivity for Cu(ClO4)2 and Cu(NO3)2
over a wide range of tested metal ions, anions, and Cu2+ salt ion pairs. Upon
adding Cu(ClO4)2 or Cu(NO3)2 to the probe solution, the fluorescence emission
was significantly turned on concomitant with a blue shift in the emission
energy, due to an anion-induced conformational change and coordination effect.
Further binding model studies by 1H nuclear magnetic resonance spectroscopy and
mass spectroscopy demonstrated that the receptor formed a 1 : 1 host–guest
complex with Cu(ClO4)2 or Cu(NO3)2.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
A series of Mn-based activated carbon catalysts were prepared by
excessive impregnation with or without ultrasonic assistance, and manganese
(Mn) species and surface chemical properties of catalysts before and after SO2
removal were studied. The results showed that different preparation conditions
significantly influence the desulfurization activity of Mn-based activated
carbon catalysts. The breakthrough sulfur capacity of 5FMn/ACA36 prepared by
ultrasonic assisted excessive impregnation is 73.0 mg g−1, while that of 5FMn/ACN36
increases to 126.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
An ultrasensitive enzyme-free electrochemical immunosensor is
constructed using a GOLDnanorods (AuNRs) modified paper electrode as the sensor
platform and porous zinc oxide spheres (PZS)–silver nanoparticles (AgNPs)
nanocomposites as signal labels. Significantly enhanced sensitivity for
prostate specific antigen (PSA) comes from a dual signal amplification
strategy. First, interconnected AuNRs layers, which can improve the electronic
transmission rate, are grown on the surface of cellulose fibers on a paper
sample zone to capture primary antibodies. Second, PZS, a porous material with
large surface area, is synthesized to provide sites for AgNPs loading, which
improves the catalytic capacity of the AgNPs towards H2O2 reduction. Under
optimized conditions, the proposed immunosensor for PSA exhibits a wide linear
detection range from 0.004 to 60 ng mL−1 with a detection limit of 1.5 pg mL−1.
Moreover, the immunosensor shows excellent selectivity, high stability, and
acceptable fabrication reproducibility. This strategy appears to be a simple
method, which provides a promising platform for the detection of other
proteins.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
In this study, a preventive method for fighting bio-deterioration of
stone substrates is proposed. This is based on the use of bioactive zinc oxide
nanoparticles (ZnO-NPs), which are able to exert a marked biological activity
over a long period of time due to their peculiar structure. ZnO-NPs are
synthesised by a simple and reproducible electrochemical procedure. The
nanomaterials are embedded in consolidant/water-repellent matrices to obtain
nanostructured coatings. Commonly used products based on tetraethoxysilane
and/or polysiloxanes were tested. The resulting nanomaterials were fully
characterised by X-ray photoelectron spectroscopy (XPS) to investigate the
amount and composition of the NPs and the behaviour of the nanocomposites.
Inductively coupled plasma mass spectrometry (ICP-MS) was used for the study of
the release of metal from the composites when put in contact with artificial
rainwater. The nanocomposites were applied to specimens composed of three
different types of stone and chromatic changes upon curing were measured by
spectrophotocolorimetry. Finally, morphological characterization by scanning
electron microscopy (SEM) was performed. The bioactivity of ZnO-NPs
nanocomposites was also assessed in preliminary tests against Aspergillus niger
fungus.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Four novel multinuclear complexes and multinuclear-based polymers with
group 12 metal centers, namely, Zn3(tpbb)Cl6 (1),
{[Cd6(tpbb)2Cl12]·2CHCl3·0.5H2O}n (2), Hg4(tpbb)Br8 (3), and Hg4(tpbb)I8 (4),
have been synthesized with respect to a new flexible tripodal ligand,
1,3,5-tris((2-(pyridine-2-yl)-1H-benzo[d]imidazol-1-yl)methyl)benzene (tpbb).
Complex 1 is a trinuclear cluster, as determined by X-ray crystallography,
while 2 features an unprecedented hexanuclear metallacycle-based 2D network
with chloride ion bridges. The similar umbrella-like tetranuclear architectures
of 3 and 4 with different Hg(II)-halide salts demonstrate that halides with the
same tetrahedral coordination geometries of metal centers do not greatly affect
the structure of the complexes. Photoluminescent studies indicate that
complexes 1 and 2 reveal enhanced and red-shifted solid-state fluorescence at
room temperature compared with the ligand, tpbb, while 3 and 4 show prominent
phosphorescence behaviors at cryogenic temperatures with lifetimes in the
microsecond range. In addition, when tested against a panel of several human
carcinoma cell lines (SH-SY5Y, QBC939 and EC109) by standard MTT assay, complex
1 displayed potential cytotoxicity against SH-SY5Y and QBC939 cells and
selectivity to different tumor cell lines.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Five new bis-cyclometalated iridium(III) complexes, [(bpbo)2Ir(acac)]
(3a), [(fbpbo)2Ir(acac)] (3b), [(Mebpbo)2Ir(acac)] (3c),
[(3,5-f2bpbo)2Ir(acac)] (3d) and [(2,4-f2bpbo)2Ir(acac)] (3e) (bpbo = 2-(biphenyl-4-yl)benzo[d]oxazole,
fbpbo = 2-(4′-fluoro-[biphenyl]-4-yl)benzo[d]oxazole, Mebpbo =
(4′-methyl-[biphenyl]-4-yl)benzo[d]oxazole, 3,5-f2bpbo =
2-(3′,5′-difluoro-[biphenyl]-4-yl)benzo[d]oxazole, 2,4-f2bpbo =
2-(2′,4′-difluoro-[biphenyl]-4-yl)benzo[d]oxazole, acac = acetylacetone), have
been synthesized and fully characterized. A single crystal X-ray diffraction
study was carried out on complexes 3a–3d, which showed that each adopted the
distorted octahedral coordination geometry with the cis-C,C′ and trans-N,N′
arrangement. All Ir(III) complexes are luminescent (560–566 nm) with quantum
yields of 3.6–53.5% and lifetimes of 0.282–0.382 μs in solution at 298 K. The
spectroscopic and redox characterisation of these complexes were complemented
by DFT and TD-DFT calculations, supporting the assignment of 3MLCT/LC to the
emissive character.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Core–shell structured Au–PtPd/C and Au–Pt/C nanoparticles (NPs) were
prepared using a successive reduction process on carbon supported Au with PtPd
and Pt particles. Structural analyses of the core–shell NPs revealed uniformly
distributed fine particles (<5 nm in diameter) on carbon particles and
selectively deposited Pt and bimetallic PtPd structures on the Au surface. The
activity of the NPs was investigated for the oxygen reduction reaction (ORR) in
both H2SO4 solutions with and without CH3OH. In Au–Pt and Au–PtPd NPs, the
activities for the ORR decreased in the solution without CH3OH as the amount of
Pd increased; moreover, Au–PtPd NPs showed higher activity than Au–Pt NPs in
solution with CH3OH due to its enhanced tolerance for methanol oxidation. Thus,
the high methanol oxidation reaction tolerance of Au–PtPd NPs is ascribed to
the synergistic effect resulting from its thin structure and bimetallic PtPd
composition.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Drinking water scarcity is a major issue that needs to be addressed
seriously. Water needs to be purified from organic pollutants and bacterial
contamination. In this study, sunlight driven photocatalysis for the
degradation of dyes and bacterial inactivation has been conducted over TiO2
nanoparticles (CST) and TiO2 nanobelts (CSTNB). TiO2 nanoparticles were
synthesized by a solution combustion process using ascorbic acid as a fuel.
Acid etched TiO2 nanobelts (CSTNB) were synthesized using combustion
synthesized TiO2 as a novel precursor. The mechanism of formation of TiO2
nanobelts was hypothesized. The antibacterial activity of combustion
synthesized TiO2 and acid etched TiO2 nanobelts were evaluated against
Escherichia coli and compared against commercial TiO2. Various characterization
studies like X-ray diffraction analysis, BET surface area analysis, diffused
reflectance measurements were performed. Microscopic structures and high
resolution images were analyzed using scanning electron microscopy,
transmission electron microscopy. The extent of photo-stability and reusability
of the catalyst was evaluated by conducting repeated cycles of photo
degradation experiments and was compared to the commercial grade TiO2. The
reactive radical species responsible for high photocatalytic and antibacterial
activity has been determined by performing multiple scavenger reactions. The
excellent charge transfer mechanism, high generation of hydroxyl and hole
radicals resulted in enhanced photocatalytic activity of the acid etched TiO2
nanobelts compared to commercial TiO2 and nanobelts made from commercial TiO2.
Website: http://www.arjonline.org/physical-sciences/american-research-journal-of-chemistry/
Herein
we report for the first time the synthesis of octadecanethiol-capped
GOLDnanoparticles (Au NPs) by sputtering of Au over a liquid matrix (silicone
oil). Au NPs prepared in silicone oil showed plasmon absorption; however, those
prepared in the presence of 1-octadecanethiol did not show plasmon absorption
but fluoresced in the near IR region.
