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New route for synthesis of electrocatalytic Ni(OH)2 modified electrodes⎯ electrooxidation of borohydride as probe reaction
No full textImmobilization of redox species like Ni(OH)2 onto the electrode surface is important in the application
areas such as super capacitor, electrochromic displays and electrocatalysis. Nickel hexacyanoferrate
(NiHCF) modified glassy carbon could be further derivatized with Ni(OH)2 by electrochemical cycling in
alkali. The electrodeposition of Ni(OH)2 was usually carried out onto the electrode surface from nickel salt at
high interfacial pH. This paper reports the preparation of Ni(OH)2 from insoluble nickel tetracyanonickelate
supported on carbon (NTN/C). This insoluble precursor complex was decomposed by two methods. (1) By
potential cycling of modified electrode with the above complex in alkali. (2) By thermal decomposition of the
precursor complex (NTN/C) to form metallic nickel followed by cycling in alkali. Ni(OH)2 modified electrodes
formed using both methods were characterized by cyclic voltammetry and also by Fourier transform infrared
spectroscopy, X-ray diffraction and scanning electron microscopy. Further, electrocatalytic properties of
Ni(OH)2/C modified electrodes formed by the above two methods were studied and compared using borohydride
oxidation as probe reactio
3-Methyltrimethylammonium poly(2,6-dimethyl-1,4-phenylene oxide) based anion exchange membrane for alkaline polymer electrolyte fuel cells
No full textHydroxyl ion (OH–) conducting anion exchange membranes based on modified poly (phenylene
oxide) are fabricated for their application in alkaline polymer electrolyte fuel cells (APEFCs). In the present
study, chloromethylation of poly(phenylene oxide) (PPO) is performed by aryl substitution rather than benzyl
substitution and homogeneously quaternized to form an anion exchange membrane (AEM). 1H NMR and FT–
IR studies reveal successful incorporation of the above groups in the polymer backbone. The membrane is
characterized for its ion exchange capacity and water uptake. The membrane formed by these processes show
good ionic conductivity and when used in fuel cell exhibited an enhanced performance in comparison with the
state-of-the-art commercial AHA membrane. A peak power density of 111 mW/cm2 at a load current density
of 250 mA/cm2 is obtained for PPO based membrane in APEFCs at 30 °C
Selective and efficient electrochemical biosensing of ultrathin molybdenum disulfide sheets
No full textAtomically thin molybdenum disulfide (MoS2) sheets were synthesized and isolated via solventassisted
chemical exfoliation. The charge-dependent electrochemical activities of these MoS2
sheets were studied using positively charged hexamine ruthenium (III) chloride and negatively
charged ferricyanide/ferrocyanide redox probes. Ultrathin MoS2 sheet-based electrodes were
employed for the electrochemical detection of an important neurotransmitter, namely dopamine
(DA), in the presence of ascorbic acid (AA). MoS2 electrodes were identified as being capable of
distinguishing the coexistence of the DA and the AA with an excellent stability. Moreover, the
enzymatic detection of the glucose was studied by immobilizing glucose oxidase on the MoS2.
This study opens enzymatic and non-enzymatic electrochemical biosensing applications of
atomic MoS2 sheets, which will supplement their established electronic application
Synthesis of Hierarchically Porous SnO2 Microspheres and Performance Evaluation as Li-Ion Battery Anode by Using Different Binders
No full textWe have prepared nanoporous SnO2 hollow
microspheres (HMS) by employing the resorcinol-formaldehyde (RF) gel method. Further, we have investigated the electrochemical property of SnO2−HMS as negative electrode material in rechargeable Li-ion batteries by employing three different binderspolyvinylidene difluoride (PVDF), Na salt
of carboxy methyl cellulose (Na-CMC), and Na-alginate. At
1C rate, SnO2 electrode with Na-alginate binder exhibits
discharge capacity of 800 mA h g−1, higher than when Na-
CMC (605 mA h g−1) and PVDF (571 mA h g−1) are used as
binders. After 50 cycles, observed discharge capacities were
725 mA h g−1, 495 mA h g−1, and 47 mA h g−1, respectively,
for electrodes with Na-alginate, Na-CMC, and PVDF binders that amounts to a capacity retention of 92%, 82%, and 8% .
Electrochemical impedance spectroscopy (EIS) results confirm that the SnO2 electrode with Na-alginate as binder had much
lower charge transfer resistance than the electrode with Na-CMC and PVDF binders. The superior electrochemical property of
the SnO2 electrode containing Na-alginate can be attributed to the cumulative effects arising from integration of nanoarchitecture
with a suitable binder; the hierarchical porous structure would accommodate large volume changes during the Li interaclation− deintercalation process, and the Na-alginate binder provides a stronger adhesion betweeen electrode film and current collecto
Low-density three-dimensional foam using self-reinforced hybrid two-dimensional atomic layers
No full textLow-density nanostructured foams are often limited in applications due to their low
mechanical and thermal stabilities. Here we report an approach of building the structural
units of three-dimensional (3D) foams using hybrid two-dimensional (2D) atomic layers
made of stacked graphene oxide layers reinforced with conformal hexagonal boron nitride
(h-BN) platelets. The ultra-low density (1/400 times density of graphite) 3D porous
structures are scalably synthesized using solution processing method. A layered 3D foam
structure forms due to presence of h-BN and significant improvements in the mechanical
properties are observed for the hybrid foam structures, over a range of temperatures,
compared with pristine graphene oxide or reduced graphene oxide foams. It is found that
domains of h-BN layers on the graphene oxide framework help to reinforce the 2D structural
units, providing the observed improvement in mechanical integrity of the 3D foam structur
Non-enzymatic organophosphorus pesticide detection using gold atomic cluster modified electrode
No full textIn this work,we report the detection of organophosphorous pesticides, particularlymethyl parathion using gold
atomic clusters (AuACs) non-enzymatically employing squarewave voltammetry (SWV). Synthesis of surfactant
stabilized gold atomic clusters on a polycrystalline gold electrode was executed by a simple potentiodynamic
cyclic voltammetry technique. The clusters are characterized using UV–visible spectroscopy and transmission
electron microscopy techniques. The electroanalytical results exhibited linear behavior in the micro (10–80 μM)
as well as nanomolar (1–10 nM) concentration ranges and the detection limit is found to be 0.65 nM (S/N=3).
The proposed sensor matrix is evaluated with real samples and the results are in good agreement with high
performance liquid chromatographic (HPLC) analysis
Influence of Structural Polymorphs on Tunable White Light Generation from Orange-Red-Emitting BiPO4:Eu3+ Phosphor by Surface Modification
No full textWe report the surface modification of orange-red-emitting
hexagonal and monoclinic polymorphs of BiPO4:Eu3+ with oleic acid (OA)
for white light generation. The surface-modified hexagonal phase emits
white light under near-UV excitation (350−395 nm) through the mixing of
broad blue emission from OA and orange-red emission from Eu3+, whereas
the same was not observed with the monoclinic phase. The variation in OA
emission upon anchoring over the surface of hexagonal BiPO4:Eu3+ resulted
in white light generation. Such variation in the interaction of OA with
surfaces of BiPO4 polymorphs and surface induced midgap states was
established through first-principles calculations that revealed the strong
interaction of OA with hexagonal phase. The deduced density of states
corroborates the experimental findings on the polymorph-dependent PL
properties of OA-modified hexagonal and monoclinic BiPO4:Eu3
Unusual seedless approach to gold nanoparticle synthesis: application to selective rapid naked eye detection of mercury(II)
No full textReport a novel seedless Hg2+-induced synthetic approach for the
preparation of gold nanostructures. This protocol is demonstrated for
the highly selective and sensitive naked eye detection of Hg2+ based
on the high affinity metallophilic Hg2+–Au+ interaction. The response
time upon exposure to Hg2+ is almost instantaneou
TiO2 coated carbon nanotubes for electrochemical energy storage
No full textMetal oxide–carbon architectures (CNTs, graphene, fullerenes, carbon spheres, etc.) have been widely
studied due to their outstanding charge storage properties. In this study, we have investigated the charge
storage mechanism in TiO2 coated CNTs. TiO2 nanoparticles are anchored to functionalized multiwalled
CNTs via controlled hydrolysis of titanium(IV) isopropoxide. The composite architecture thus produced
was composed of uniformly coated TiO2 particles (size ranging from 10–30 nm) around the CNTs'
surface. The Li-ion storage in TiO2 coated CNTs was investigated using cyclic voltammetry (CV) and
galvanostatic charge–discharge experiments. Galvanostatic cycling illustrates a high capacity of 470 mA
h g�1 for the composite electrode, a value higher than the theoretical specific capacity (335 mA h g�1) of
anatase TiO2. Electrochemical analysis using CV measurements indicates the total charge storage value
observed is the cumulative response of diffusion controlled and non-diffusion controlled processes. The
repartition of the total charge storage contribution indicates the dominance of Li-intercalation at the
peak potential and the capacitive surface reactions at the rest of the potentials in the operating voltage
window of 1.5–2.2 V. Hence the nano composite reported here shows the importance of synergistic
charge storage contribution from Li-ion insertion and pseudocapacitance resulting in high capacity
electrode materia
Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry
No full textThe electrochemical bromination of 4-methoxy toluene by two-phase electrolysis
yields 3-bromo 4-methoxy toluene at first, which subsequently undergoes side-chain bromination
to give 3-bromo 4-methoxy benzyl bromide as a final product in 86% yield. The
two-phase electrolysis consists of 25–50% NaBr as aqueous electrolyte and CHCl3 containing
aromatic compound as organic phase. The reaction temperature is maintained at
10–25 �C. The probable orientation of bromine atom in an alkyl aromatic compound
(nuclear versus side chain) is explained from the experimental resul