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253 results on '"Swaminathan, Meenakshisundaram"'

40. Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid supported montmorillonite K-10 clay-catalysed one-pot multi-component synthesis of chromeno[2,3-b]indoles

Author

Kumaresan Murugan, Sami Ponnusamy, Prasanna Antony Muthu, and Swaminathan Meenakshisundaram

Subjects
Indole test, Montmorillonite K-10, 010405 organic chemistry, Condensation, General Chemistry, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, Montmorillonite, chemistry, Salicylaldehyde, Yield (chemistry), Organic chemistry, Oxindole
Abstract

One-pot three-component synthesis of twelve different chromeno[2,3-b]indole derivatives were achieved by the condensation of β-naphthol, oxindole and various substituted aldehydes. Two more chromeno[2,3-b]indole derivatives were also synthesized through one-pot two-component condensation of salicylaldehyde with oxindole/chlorooxindole. Both the condensations were achieved by using Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid, H4[PVMo11O40] supported on montmorillonite K-10 clay for about 10% as catalyst under environmentally benign solvent-free reaction condition. Shorter reaction time, excellent yield of product, sustainability of catalytic material and simple workup procedure under green experimental conditions are the advantages of this protocol.

Published
2021

41. Versatile fabrication and characterization of Cu-doped ZrO2 nanoparticles: enhanced photocatalytic and photoluminescence properties

Author

Akilandeswari Sambandam, Mohamad S. AlSalhi, Swaminathan Meenakshisundaram, Thirumalai Kuppulingam, Rajesh Gopal, and Sandhanasamy Devanesan

Subjects
010302 applied physics, Materials science, Methyl blue, Methyl violet, chemistry.chemical_element, Condensed Matter Physics, 01 natural sciences, Copper, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, Tetragonal crystal system, chemistry, X-ray photoelectron spectroscopy, 0103 physical sciences, Photocatalysis, Crystallite, Electrical and Electronic Engineering, Nuclear chemistry, Monoclinic crystal system
Abstract

Pristine ZrO2 and molar ratios of Cu-doped ZrO2 nanoparticles were synthesized by chemical precipitation. The XRD pattern of pristine ZrO2 and Cu-doped ZrO2 nanoparticles shows the formation of t-tetragonal phase and shifting of tetragonal phase to monoclinic phase. The average crystallite sizes of the pristine ZrO2 and Cu-doped ZrO2 nanoparticles were calculated as 2.9, 4.65, 4.76, 5.02, and 4.96 nm, respectively. The Cu (0.06 M)-doped ZrO2 nanoparticles are present as spherical morphology and high agglomeration was confirmed by FE-SEM and TEM analyses. The XPS spectra affirmed the presence of Cu2+, Zr4+, and oxygen ions in the Cu (0.06 M)-doped ZrO2 nanoparticles. The Cu-doped ZrO2 nanoparticles exhibit two energy gaps at 5.30 and 3.05 eV, 5.21 and 2.22 eV, 4.65 and 2.11 eV, and 4.44 and 2.65 eV. The surface defects and oxygen vacancies were analyzed by PL and ESR spectroscopy. The ESR spectra are clearly asymmetric in shape and contain a peak signal related to the presence of the copper species (Cu2+) in the distorted tetragonal coordination of ZrO2. The photocatalytic activities of Cu (0.06 M)-doped ZrO2 nanoparticles were successfully sought on degradation of the two azo dyes: methyl violet and methyl blue under sunlight irradiation. Cu (0.06 M)-doped ZrO2 showed complete degradation at 70 min. The reusability of Cu (0.06 M)-doped ZrO2 nanoparticles shows maximum degradation efficiency for six successive runs.

Published
2020

44. Rational Design of Single Tungsten/Cobalt Atom Oxide Anchored on the Tio2-Rgo: A Highly Efficient Electrocatalyst for Water Splitting and Photocatalyst for Decomposition of Pharmaceutical Pollutants

Author

Selvakumar, Karuppaiah, primary, Oh, Tae Hwan, additional, Wang, Yueshuai, additional, Prasanna, Antony Muthu, additional, Arunpandian, Muthuraj, additional, Thangarasu, Sadhasivam, additional, Sami, Ponnusamy, additional, and Swaminathan, Meenakshisundaram, additional

Published
2022
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46. Photo-electrocatalytic activity of praseodymium oxide modified titania nanorods.

Author

Balachandran, Subramanian, Karthikeyan, Rajan, Selvakumar, Karuppaiah, and Swaminathan, Meenakshisundaram

Subjects
CATALYST structure, PRASEODYMIUM, RUTILE, OXIDATION of methanol, NANORODS, DECOMPOSITION method, AZO dyes
Abstract

Modification of semiconductor oxides leads to a major development in functional characteristics. Characterisation of Pr6O11-TiO2, fabricated by a cost-effective hydrothermal – decomposition method reveals the nanorod like structure of this catalyst. The XRD pattern definite the formation of face-centred cubic or cubic close-packed structure of Pr6O11 and the high crystallinity indicate the existence of anatase TiO2. XPS analysis indicates the presence of both Pr3+and Pr4+ ions in Pr6O11. Pr6O11-TiO2 is more photoactive under visible light than Pr6O11, prepared TiO2 and TiO2-P25 (80% Anatase and 20% Rutile mixture) in the degradation of toxic azo dyes. Pr6O11-TiO2 is stable and recyclable consecutively. Pr6O11-TiO2 catalyst shows higher electrocatalytic activity in methanol oxidation than pure TiO2. These results reveal new insights on the efficiency of catalysts in photo- and electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Published
2022
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