CdS microspheres composed of nanocrystals and their photocatalytic activity.

Rengaraj, Selvaraj,Jee, Sun Hee,Venkataraj, Selvaraj,Kim, Younghun,Vijayalakshmi, Selvaraj,Repo, Eveliina,Koistinen, Arto,Sillanp??, Mika American Scientific Publishers 2011 Journal of Nanoscience and Nanotechnology Vol.11 No.3

<P>A simple and template-free solution phase synthesis method has been developed for the preparation of novel CdS hollow microspheres using cadmium nitrate and thioacetamide precursors. In this manuscript, we demonstrate that process parameters such as the reaction time, precursor ratio, and reaction temperature strongly influence the morphology of the final product. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray diffraction (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-DRS). XRD analysis confirmed the cubic structure of the CdS microspheres, which has also been further supported by Raman spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres which has been evolved by the oriented aggregation of the primary CdS nanocrystals. The TEM measurements confirmed the hollow shell-like structure of the spheres; the formation of their hollow interiors can be explained by the Ostwald ripening mechanism. UV-DRS studies showed that the band gap of the CdS microspheres increased with increasing cadmium-nitrate-to-thioacetamide ratio. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading methyl tert-butyl ether (MTBE) in aqueous solution under visible-light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.</P>

Embargo Nature of CuO-PANI Composite Against Corrosion of Mild Steel in Low pH Medium

Selvaraj, P. Kamatchi,Sivakumar, S.,Selvaraj, S. The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.2

Incorporation of CuO nanoparticles during the polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidizing agent and sodium salt of dodecylbenzene sulphonic acid as dopant as well as surfactant yielded water soluble CuO-PANI composite. Comparison of recorded spectra like FTIR, XRD and SEM with reported one confirm the formation of the composite. Analysis by gravimetric method exposes that the synthesized composite is having resistivity against corrosion, with slight variation in efficiency on extending the time duration up to eight hours in strong acidic condition. OCP measurement, potentiodynamic polarization and EIS studies also confirms the suppression ability of composite against corrosion. Riskless working environment could be provided by the synthesized composite during industrial cleaning process.

Stabilization of cryptomelane α-MnO₂ nanowires tunnels widths for enhanced electrochemical energy storage

Selvaraj, Aravindha Raja,Rajendiran, Rajmohan,Chinnadurai, Deviprasath,Rajendra Kumar, Gunasekaran,Kim, Hee-Je,Senthil, Karuppanan,Prabakar, Kandasamy Elsevier 2018 ELECTROCHIMICA ACTA Vol.283 No.-

<P><B>Abstract</B></P> <P>One dimensional manganese oxides with tunnel structures have attracted as an effective electrochemical energy storage material because of its efficient electrolyte/cation interfacial charge transports which enables improved pseudo capacitive performance. We have reported a simple one step hydrothermal technique to incorporate K<SUP>+</SUP> ions to maintain the tunnel width of cryptomelane α-MnO<SUB>2</SUB> nanowires during cycling performance. The effects of K<SUP>+</SUP> ions on the electrochemical performance is studied by tuning the phases of α-KMnO<SUB>2</SUB> nanowires to Mn<SUB>3</SUB>O<SUB>4</SUB> through an intermediate phase of Mn<SUB>2</SUB>O<SUB>3</SUB> by subsequent calcinations at various temperatures. K<SUP>+</SUP> ions doped α-MnO<SUB>2</SUB> nanowires exhibit a highest specific capacitance of 402 Fg<SUP>-1</SUP> at a current density of 1 Ag<SUP>-1</SUP> in 1 M Na<SUB>2</SUB>SO<SUB>4</SUB> electrolyte solution compared to Mn<SUB>2</SUB>O<SUB>3</SUB> and Mn<SUB>3</SUB>O<SUB>4</SUB>. The as synthesized α-KMnO<SUB>2</SUB> nanowires have a wider tunnel widths and enriched OH radical species and hence the electrolyte cations (Na<SUP>+</SUP>) penetrate the tunnels very easily resulting the polarization enhanced intercalation pseudo capacitance. The symmetric α-KMnO<SUB>2</SUB> nanowire supercapacitor device shows very high energy density (15.83 Wh kg<SUP>−1</SUP>), power density (128.35 W kg<SUP>−1</SUP>) and excellent cyclic stability with 88% retention of the initial capacitance after 3000 cycles.</P>

Selective synthesis of vitamin K₃ over mesoporous NbSBA-15 catalysts synthesized by an efficient hydrothermal method

Selvaraj, M.,Park, D.-W.,Kim, I.,Kawi, S.,Ha, C. S. The Royal Society of Chemistry 2012 Dalton Transactions Vol.41 No.32

<P>Well hexagonally ordered NbSBA-15 catalysts synthesized by an efficient hydrothermal method were used, for the first time, for the selective synthesis of vitamin K<SUB>3</SUB> by liquid-phase oxidation of 2-methyl-1-naphthol (2MN1-OH) under various reaction conditions. The recyclable NbSBA-15 catalysts were also reused to find their catalytic activities. To investigate the leaching of non-framework niobium species on the surface of silica networks, the results of original and recyclable NbSBA-15 catalysts were correlated and compared. To find an optimum condition for the selective synthesis of vitamin K<SUB>3</SUB>, the washed NbSBA-15(2.2pH) was extensively used in this reaction with various reaction parameters such as temperature, time and ratios of reactant (2M1N-OH to H<SUB>2</SUB>O<SUB>2</SUB>), and the obtained results were also demonstrated. Additionally, the liquid-phase oxidation of 2M1N-OH was carried out with different solvents to find the best solvent with a good catalytic activity. Based on the all catalytic studies, the vitamin K<SUB>3</SUB> selectivity (97.3%) is higher in NbSBA-15(2.2pH) than that of other NbSBA-15 catalysts, and the NbSBA-15(2.2pH) is found to be a highly active and eco-friendly heterogeneous catalyst for the selective synthesis of vitamin K<SUB>3</SUB>.</P> <P>Graphic Abstract</P><P>Mesostructured NbSBA-15 catalysts were used, in novel green routes, for the synthesis of vitamin K<SUB>3</SUB> from 2-methyl-1-naphthol. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2dt31096a'> </P>

Rapid-Response and Highly Sensitive Boronate Derivative-Based Fluorescence Probe for Detecting H ₂ O ₂ in Living Cells

Selvaraj, Muthusamy,Rajalakshmi, Kanagaraj,Nam, Yun-Sik,Lee, Yeonhee,Kim, Byoung Chan,Pai, Sung Jin,Han, Sang Soo,Lee, Kang-Bong Hindawi 2019 Journal of analytical methods in chemistry Vol.2019 No.-

<P>Intracellular H<SUB>2</SUB>O<SUB>2</SUB> monitoring is important and has driven researchers to pursue advancements for the rapid identification of H<SUB>2</SUB>O<SUB>2</SUB>, since H<SUB>2</SUB>O<SUB>2</SUB> is short-lived in cell lines. An arylboronate derivative has been investigated as a chemospecific fluorescence recognition agent for H<SUB>2</SUB>O<SUB>2</SUB>. Triphenylimidazoleoxadiazolephenyl (TPIOP) boronate was contrived as a novel candidate for the rapid and sensitive recognition of H<SUB>2</SUB>O<SUB>2</SUB>. The probe was conjugated using the TPIOP functional group acting as an excellent fluorescent enhancer. The TPIOP group stimulated the polarization of C–B bond due to its extended <I>π</I>-conjugation, which included heteroatoms, and induced the production of rapid signal because of the highly polar C–B bond along with the corresponding boronate unit. While H<SUB>2</SUB>O<SUB>2</SUB> reacts with TPIOP boronate, its nucleophilic addition to the boron generates a charged tetrahedral boronate complex, and then the C–B bond migrates toward one of the electrophilic peroxide oxygen atoms. The resulting boronate ester is then hydrolyzed by water into a phenol, which significantly enhances fluorescence through aggregation-induced emission. The TPIOP boronate probe responded to H<SUB>2</SUB>O<SUB>2</SUB> rapidly, within 2 min, and exhibited high sensitivity with a limit of detection of 8 nM and a 1000-fold selectivity in the presence of other reactive oxygen species. Therefore, the developed TPIOP boronate chemodosimeter was successfully utilized to visualize and quantify intracellular H<SUB>2</SUB>O<SUB>2</SUB> from human breast cancer (MCF-7) cells, as well as gaseous and aqueous H<SUB>2</SUB>O<SUB>2</SUB> from environmental samples using Whatman paper strips coated with TPIOP boronate.</P>

On-off-on relay fluorescence recognition of ferric and fluoride ions based on indicator displacement in living cells

Selvaraj, Muthusamy,Rajalakshmi, Kanagaraj,Nam, Yun-Sik,Lee, Yeonhee,Song, Jong-Won,Lee, Ho-Jin,Lee, Kang-Bong Elsevier 2019 Analytica Chimica Acta Vol.1066 No.-

<P><B>Abstract</B></P> <P>A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential “on-off-on”-type relay fluorescence probe for Fe<SUP>3+</SUP> ions and F<SUP>−</SUP> ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe<SUP>3+</SUP> to IOP boronic acid (IOPBA) formed an Fe<SUP>3+</SUP> IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe<SUP>3+</SUP> ion in the Fe<SUP>3+</SUP> IOPBA complex was coordinated to two phenyl groups to form a π-complex. Upon addition of F<SUP>−</SUP> to the Fe<SUP>3+</SUP> IOPBA complex, the original fluorescence was recovered due to formation of [FeF<SUB>6</SUB>]<SUP>3‒</SUP>, resulting in “on-off-on”-type sensor behavior. IOPBA showed high selectivity towards Fe<SUP>3+</SUP> among other cations. Moreover, the Fe<SUP>3+</SUP> IOPBA complex showed specific selectivity towards F<SUP>−</SUP>, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 10<SUP>6</SUP> and 4.49 × 10<SUP>6</SUP> mol<SUP>−1</SUP> L for Fe<SUP>3+</SUP> with IOPBA and F<SUP>−</SUP> with Fe<SUP>3+</SUP> IOPBA, respectively. The limits of detection for Fe<SUP>3+</SUP> and F<SUP>−</SUP> were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe<SUP>3+</SUP> and F<SUP>−</SUP> in living HeLa cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Imidazole oxadiazole boronic acid derivative (IOPBA) was designed and synthesized. </LI> <LI> IOPBA showed highly sensitive and selective response for Fe<SUP>3+</SUP> and F<SUP> <B>−</B> </SUP>. </LI> <LI> On-off-on type relay response was achieved at Fe<SUP>3+</SUP> IOPBA with F<SUP> <B>−</B> </SUP>. </LI> <LI> The probe expressed LODs of 10 and 1 nM for Fe<SUP>3+</SUP> and F<SUP>−</SUP>, respectively. </LI> <LI> IOPBA can be utilized as bioimaging reagent for Fe<SUP>3+</SUP> and F<SUP>−</SUP> in living HeLa cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrical and Thermal Characterization of Organic Varnish Filled with ZrO₂ Nano Filler Used in Electrical Machines

Selvaraj, D. Edison,Vijayaraj, R.,Sugumaran, C. Pugazhendhi The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO₂) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.

Synthesis and photo-electrochemical properties of spinel-ferrite-coated hematite for solar water splitting

Selvaraj, Seenivasan,Moon, Hee,Kim, Do-Heyoung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.429 No.-

<P><B>Abstract</B></P> <P>Photo-electrochemical water splitting with hematite photo-anodes under solar irradiation has attracted considerable attention as regards the production of renewable hydrogen energy. However, many challenges remain unresolved, as the full contribution of the catalytic over-layers has not been fully realized. Herein, we incorporate uniform spinel nickel-ferrite over-layers in hematite photo-anodes to obtain an improved understanding of the associated intrinsic changes. We achieve a 1.5-mA/cm<SUP>2</SUP> photo-current density at 1.23V<SUB>RHE</SUB> (RHE: reversible hydrogen electrode) under one-sun illumination conditions, along with a negative shift of 200mV in the onset potential, for NiFe<SUB>2</SUB>O<SUB>4</SUB>-coated Sn-doped hematite photo-anodes. Fundamental electrochemical analyses clearly show that the shift in the onset potential is predominantly due to the enhanced photo-voltage development inside the hematite, rather than being purely caused by the interfacial kinetics. These insights reveal a new direction for fundamental research on photo-anodes towards fabrication of more efficient photo-anode systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spinel ferrite was evaluated for use as a high-performance photo-anode material. </LI> <LI> A nickel-ferrite over-layer was successfully formed on a 1-D hematite nanorod. </LI> <LI> Improved photo-electrochemical performance was achieved through an increase in the photo-voltage and a decrease in the kinetic over-potential. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Application of Nano Coating to ACSR conductor for the Protection of Transmission lines against Solar Storms, Surface Flashovers, Corona and Over voltages

Selvaraj, D. Edison,Mohanadasse, K.,Sugumaran, C. Pugazhendhi,Vijayaraj, R. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

Nano composite materials were multi-constituent combinations of nano dimensional phases with distinct differences in structure, chemistry and properties. Nano particles were less likely to create large stress concentrations and thereby can avoid the compromise of the material ductility while improve other mechanical properties. Corona discharge was an electrical discharge. The ionization of a fluid surrounding a conductor was electrically energized. This discharge would occur when the strength of the electric field around the conductor was high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects. This paper shows all the studies done on the preparation of nano fillers. Special attention has given to the ACSR transmission line conductor, TiO₂ nano fillers and also to the evaluation of corona resistance on dielectric materials discussed in detail. The measurement of the dielectric properties of the nano fillers and the parameters influencing them were also discussed in the paper. Corona discharge test reveals that in 0%N ACSR sample corona loss was directly proportional to the applied line voltage. No significant change in corona loss between 0%N and 1%N. When TiO₂ nano filler concentration was increased up to 10%N fine decrement in corona loss was found when compared to base ACSR conductor, corona loss was decreased by 40.67% in 10%N ACSR sample. It was also found from the surface conditions test that inorganic TiO₂ nano filler increases the key parameters like tensile strength and erosion depth.

Selective synthesis of 6,8-di-<i>t</i>-butylated flavan over Zn–Al containing mesoporous silica catalysts

Selvaraj, M.,Sinha, P. K.,Park, D.-W.,Kim, Il,Kawi, S.,Ha, C. S. The Royal Society of Chemistry 2012 Dalton Transactions Vol.41 No.46

<P>We demonstrate a much green synthesis method for highly selective synthesis of 6,8-di-<I>t</I>-butylated flavan (6,8-DTBF) by liquid phase alkylation of 2,4-di-<I>t</I>-butylphenol (2,4-DTBP) with cinnamyl alcohol (Cin-OH) over mesoporous Zn–Al–MCM-41 catalysts synthesized under direct basic hydrothermal method. The main alkylated product, 6,8-DTBF is importantly used as an intermediate in the manufacture of biosynthetic organic compounds. The recyclable mesoporous Zn–Al–MCM-41 catalysts have also been reused in this reaction to study their catalytic activities. The influences of various reaction parameters such as temperature, time, ratios of reactant (2,4-DTBP-to-Cin-OH) have been extensively investigated for the synthesis of 6,8-DTBF. In addition, dimethyl sulfoxide (DMSO) has also been used as a solvent in this catalytic reaction. The mesoporous Zn–Al–MCM-41(75) gives excellent catalytic activity with 6,8-DTBF selectivity (86.0%) and 2,4-DTBP conversion (63.1%), and these catalytic results have also compared with that obtained using other mesoporous and microporous catalysts. On the basis of catalytic activity obtained by using the all catalysts, the Zn–Al–MCM-41(75) catalyst is found to be a highly active, recyclable and eco-friendly heterogeneous catalyst in the liquid-phase alkylation of 2,4-DTBP.</P> <P>Graphic Abstract</P><P>Zn–Al–MCM-41(75) catalyst is found to be a highly active, recyclable and eco-friendly green catalyst in the liquid-phase alkylation of 2,4-DTBP. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2dt31409f'> </P>