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A novel potentiometric hydrogen peroxide sensor based on pKa changes of vinylphenylboronic acid membranes
No full textA potentiometric hydrogen peroxide (H2O2) sensing scheme was developed using arylboronic acid as the electrode modifier. It is well-known that both aliphatic and aryl boronic acid undergo electrophilic displacement reaction with H2O2. This reaction involves replacement of boronic acid by the hydroxyl group of peroxide resulting in a change in pKa value that can be exploited for sensing of H2O2. Vinylphenylboronic acid (VPBA) ink was prepared using Nafion as the binder and it was drop cast on an electrode surface. Morphology of the modified electrode was analysed using scanning electron microscopy (SEM). The present modifier exhibited a linear relationship between the difference in electrode potential (ΔEp) vs. [H2O2] with a Nernstian slope of 26±2 mV in the concentration range of 10−1–10−5 M. Application of the VPBA modified electrode
for hydrogen peroxide sensing was studied in an industrial dye-bleach effluen
Influence of substrate temperature on the materials properties of reactive DC magnetron sputtered Ti/TiN multilayered thin films
No full textTi/TiN multilayers were deposited by DC reactive magnetron sputtering method using a titanium target and an Ar–N2 mixture discharge gas. XRD technique was employed to study the structure of the coatings and to observe the variations of structural parameters with substrate temperatures. An increase in grain size with increase of substrate temperature was observed. The components of Ti 2p doublet, related to TiN, TiON and TiO2, were observed in the core-level spectra of the deposited multilayer films from
XPS analysis. A microhardness value of 25.5 GPa was observed for Ti/TiN multilayers prepared at 400 ◦C.
Electrical properties were found to depend on substrate temperatur
Improved performance of polyvinylidenefluoride-hexafluoropropylene based nanocomposite polymer membranes containing lithium bis(oxalato)borate by phase inversion for lithium batteries
No full textNanocomposite polymer electrolyte membranes were prepared by phase inversion technique in polyvinylidenefluoride-hexafluoropropylene (PVdFeHFP) matrix. These membranes were gelled with 0.5 M LiBOB in EC:DEC (1:1 v/v). These gel polymer membranes (GPMs) were incorporated with nanoparticles of AlO(OH)n and prepared composite polymer membranes (CPMs) also. The a.c. impedance analysis shows that AlO(OH)n filled membrane exhibits conductivity of 1.82 - 10-3 S cm-1 at ambient temperature. The Li/CPM/LiFePO4 cell delivered a specific discharge capacity of 158 and 147 mAh g-1 at first and at 20th cycle respectively discharged at C/20 rate. The cell experiences a capacity fade of 0.1 mAh g-1 cycle-1 over the investigated 20 cycles. The studies vindicate that AlO(OH)n filled PVdFeHFP polymer
membranes could be the potential material to use as separator cum electrolyte in lithium batteries in
conjunction with LiFePO4 as a counterpar
Anodically fabricated TiO2 nanopores for electrocatalytic reduction of aldehydes
No full textUniformly ordered titanium dioxide (TiO2) nanopores surface was synthesized by anodizing the titanium at different applied voltages 20, 30 and 40 V for 8 h in an electrolyte consisting of 0.3 wt.% NH4F and 2 vol.% H2O in ethylene glycol. The pores diameter was found to increase with applied voltage. Scanning electron microscopic studies revealed that the fabricated TiO2 nanopores have an average pore diameter of 100 nm approximately and increasing with applied voltage. X-ray diffraction, cyclic voltammetry (CV)
and impedance spectroscopy studies were employed to characterize the TiO2 nanoporous film and current
increase in the CV studies confirmed the increase in surface area. Electrocatalytic behavior of Ti/TiO2 nanopores was investigated for the reduction of aldehydes using cyclic voltammetry. It was observed that the nanopores catalytically reduced the benzaldehyde and furfural to corresponding alcohol. Bulk electrolysis studies were also carried out for the reduction of benzaldehyde and the product was confirmed by NMR. The two time constants in impedance study showed the involvement of pores in the reduction behavio
Electrochemical Unzipping of Multi-walled Carbon Nanotubes for Facile Synthesis of High-Quality Graphene Nanoribbons
No full textHere we report a remarkable transformation
of carbon nanotubes (CNTs) to nanoribbons composed of
a few layers of graphene by a two-step electrochemical
approach. This consists of the oxidation of CNTs at controlled
potential, followed by reduction to form graphene
nanoribbons (GNRs) having smooth edges and fewer
defects, as evidenced by multiple characterization techniques, including Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. This type of “unzipping” of CNTs (single-walled, multi-walled) in the
presence of an interfacial electric field provides unique
advantages with respect to the orientation of CNTs, which
might make possible the production of GNRs with controlled
widths and fewer defects
Functionalization of SBA-15 Mesoporous Materials using Thiol-Ene“Click” Michael Addition Reaction
No full textMethacrylate-labeled SBA-15 has been successfully synthesized from calcined SBA-15 and commercially available 3-trichlorosilyl propylmethacrylate. This material undergoes efficient thiol-ene “click reaction” with a variety of both thiol- and disulfide-containing substrates in aqueous and organic media. The products were thoroughly characterized by a variety of analytical techniques including multinuclear (13C, 29Si)solid-state NMR, TG-DTA, and nitrogen adsorption desorption studies. Disulfide-containing substrates in which the TCEP mediated reduction of the disulfide bond and its subsequent addition to the methacrylate group anchored in SBA-15 in one-pot were used to synthesize a silica-protein hybrid material composed of biotin-labeled SBA-15 and streptavidin. Electrochemically active material was synthesized from the reaction of ferrocene-containing thiol and the methacrylate-labeled SBA-15. The ease of synthesis for the methacrylate-labeled
SBA-15 material together with its ability to undergo efficient chemoselective thiol-ene reaction would make it a very attractive
22 platform for the development of covalently anchored enzymes and sensors
Application of Functionalized CNT–Polymer Composite electrolytes for Enhanced Charge Storage in “All Solid-State Supercapacitors”
No full textThe ability of specifically functionalized carbon nanotubes to enhance proton transport in Nafion and polybenzimidazole membranes leading to improvement in the specific capacitance of an all solid-state supercapacitor is demonstrated. Cyclic voltammetry experiments reveal a 25% improvement (185 and 150 F per gram of RuO2 for composite and Nafion membranes respectively) in capacitance by a meager 0.05 wt% addition of sulfonated MWCNTs in Nafion membranes. On the other hand, an addition of 1% phosphonated MWCNTs results in ∼60% improvement in polybenzimidazole (PBI) based composites (from 160 to 260 F g−1�. Further, composite membranes
based on functionalized MWCNTs show increased cycle life which is attributed to the presence of
electrostatically linked network structures due to functional moieties on the side walls of carbon
nanotubes that increases the interfacial charge density and integrity of the membrane. The equivalent
series resistance for the PBI and PBI phosphonated MWCNT (PBpNT) membranes is 470 and 89 m� respectively suggesting improved proton conductivity with the composite membrane. Charge discharge measurements reveal a capacitance value of 500 F g−1 for PBpNT membrane based supercapacitors even after 1000 cycles of operation. Use of such nanocomposite membranes is expected to dramatically improve the life time as well as performance of supercapacitors which in turn would facilitate deployment in different applications such as hybrid electric vehicles
Catalytic activity of dendrimer encapsulated Pt nanoparticles anchored onto carbon towards oxygen reduction reaction in polymer electrolyte fuel cells
No full textPt nanoparticles are encapsulated in the fourth-generation hydroxyl-terminated poly (amidoamine)(PAMAM) dendrimer (G4-OH) and anchored onto carbon to realize a novel cathode catalyst for polymer electrolyte fuel cells (PEFCs). Extensive physical and electrochemical characterizations confirm that Pt/G4-OH-C catalyst exhibits significant enhancement of catalytic activity towards oxygen reduction
reaction (ORR). The mass activities (A mgPt −1) at 0.9 V vs. RHE for Pt/G4-OH-CI and Pt/G4-OH-CII, both prepared by different routes, are enhanced by 3.6 and 2.6 times, respectively, in relation to Pt/C catalyst. Dendrimer template studied here provides size-controlled preparation of Pt-based catalyst and facilitates uniform dispersion and loading of the catalyst onto carbon support. It is noteworthy that a PEFC comprising Pt/G4-OH-C catalyst with a Pt loading of ∼0.1 mg cm−2 delivers a power density of 712 mW cm−2 at 0.6 V with H2 and O2 feeds. By contrast, the PEFC using Pt/C with a Pt loading of ∼0.2 mg cm−2 delivers
a power density of only 370 mW cm−2 while operating under similar condition
Environmental effects on concrete using ordinary and pozzolana portland cement
No full textWastewater treatment plant consists of pipe lines and lift stations. These plants consist of concrete pipes,
manholes, pump stations, interceptors and wet wells. Entire wastewater (WW) system is forced to chemical attack due to the presence of sulphate and acid available in WW. It leads to the damage in the interior wall or structure of a sewer pipe and lift station. A concrete structure when exposed to different environments, the life of the structure is drastically reduced. Main cause of the deterioration is corrosion or erosion. The defective structures are replaced periodically which leads to indirect loss in the national growth. In other words, the failure of these structures may lead to invest more on the repair and rehabilitation.
In this study, the strength of the concrete in various environments has been investigated using different
techniques such as compressive strength, flexural test, rapid chloride permeability, weight loss measurements,
linear polarization and open circuit potential. Microbiological examinations were also analyzed. Two types of cement namely Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC) with one mix ratio were used for complete study. Concrete specimens exposed in three environments namely: normal water (NW Potable water), domestic sewage water (DSW) and textile wastewater (TWW). From the results, it is observed that PPC exposed in different media shows better performance than OPC in both
mechanical and electrochemical studie
Electrosynthesis of polyaniline–molybdate coating on steel and its corrosion protection performance
No full textElectrosynthesis of polyaniline–molybdate (PANI–MoO42−) on mild steel was achieved in oxalic acid medium using cyclic voltammetry technique. Adherent and homogeneous PANI–MoO4
2− coating was obtained. The corrosion behavior of steel with PANI–MoO4 2− coatings in 1% NaCl solutions was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The
coating was characterized by SEM, XPS, EDAX and FTIR. The self-healing ability of PANI–MoO4 2− coating
was confirmed by SVET technique. It has been found that the PANI–MoO42− coating is able to offer higher corrosion protection in comparison to that of pure PANI coating due to inhibitive nature of molybdate ion