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Suresh D.,Tumkur University | Nagabhushana H.,Tumkur University | Sharma S.C.,Chattisgarh Swami Vivekanand Technical University
Materials Letters | Year: 2015

The study reports a facile green method for the effective reduction of graphene oxide (GO) using Cloves (Syzygium aromaticum) extract by a reflux method at 100°C for 30 min. Formation of a few layered reduced graphene oxide (rGO) was confirmed by XRD, TEM and UV-visible studies. Carcinogenic dye degradation and antioxidant properties of the rGO were evaluated. Methylene blue (MB) and Malachite green (MG) dyes were found to be eliminated completely within 20 min in dark condition in the presence of 20 mg rGO. The prepared rGO was found to have IC50 value of 1337 μg/ml towards quenching of DPPH free radicals. The investigation describes an environment friendly and cost effective method for the green reduction of GO to attain multifunctional rGO. © 2014 Elsevier B.V. All rights reserved. Source


Nethravathi P.C.,Tumkur University | Pavan Kumar M.A.,Tumkur University | Suresh D.,Tumkur University | Lingaraju K.,Tumkur University | And 4 more authors.
Materials Science in Semiconductor Processing | Year: 2015

The study reports a facile method for the green synthesis of copper oxide nanoparticles (CuO Nps) by a solution combustion method using Tinospora cordifolia water extract. The Nps were characterized by XRD, SEM, TEM and UV-visible studies. XRD data indicates the formation of pure monoclinic crystallite structures of CuO Nps. SEM images show that the particles have sponge like structure with large surface area and the average crystallite sizes were found to be ~6-8 nm. These observations were confirmed by TEM analysis. Photocatalytic activity studies of CuO Nps reveal that they act as very good catalyst for the effective degradation of methylene blue (MB) in the presence of UV and Sun light. Also, the degradation of MB was found to be pH dependent. The Nps found to inhibit the activity of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals effectively. CuO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. The study reveals a simple, ecofriendly and robust method for the synthesis of multifunctional CuO nanoparticle employing underutilized medicinal plants. © 2015 Elsevier Ltd. Source


Nethravathi P.C.,Tumkur University | Shruthi G.S.,Tumkur University | Suresh D.,Tumkur University | Nagabhushana H.,Tumkur University | And 2 more authors.
Ceramics International | Year: 2015

Green synthesis of multifunctional zinc oxide nanoparticles (ZnO Nps) was achieved employing water extract of Garcinia xanthochymus by solution combustion synthesis. The structure and morphology were determined by XRD, UV-visible and scanning electron microscopy studies. The ZnO Nps were evaluated for photoluminescence (PL), photocatalytic and antioxidant properties. The water extract was found to comprise significantly high amounts of polyphenols and flavonoids. Powder XRD studies indicate the formation of pure wurtzite structure with absorption maximum of 370 nm corresponding to band gap energy of 3.33 eV. SEM studies reveal the formation of spongy cave like structures. The PL spectra exhibited 4 emission edges at 397, 436, 556 and 651 nm upon excitation at 325 nm because of oxygen deficiencies and zinc interstitials. Nps exhibit remarkable photodegradation of methylene blue (MB) in presence of UV and sun light. They exhibit antioxidant activity by inhibiting the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Therefore, the study reveals an efficient, ecofriendly and simple method for the green synthesis of multifunctional ZnO Nps. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Suresh D.,Tumkur University | Udayabhanu,Tumkur University | Nethravathi P.C.,Tumkur University | Lingaraju K.,Tumkur University | And 3 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

(Figure Presented) Zinc oxide nanopowders were synthesized by solution combustion method using Epigallocatechin gallate (EGCG) a tea catechin as fuel. The structure and morphology of the product was characterized by Powder X-ray Diffraction, Scanning Electron Microscopy, photoluminescence and UV-Visible spectroscopy. The nanopowders (Nps) were subjected to photocatalytic and biological activities such as antimicrobial and antioxidant studies. PXRD patterns demonstrate that the formed product belongs to hexagonal wurtzite system. SEM images show that the particles are agglomerated to form sponge like structure and the average crystallite sizes were found to be ∼10-20 nm. PL spectra exhibit broad and strong peak at 590 nm due to the Zn-vacancies, and O-vacancies. The prepared ZnO Nps exhibit excellent photocatalytic activity for the photodegradation of malachite green (MG) and methylene blue (MB) indicating that the ZnO NPs are potential photocatalytic semiconductor materials. ZnO NPs exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus using the agar well diffusion method. Furthermore, the ZnO nano powders show good antioxidant activity by potentially scavenging DPPH radicals. The study successfully demonstrates synthesis of ZnO NPs by simple ecofriendly route employing EGCG as fuel that exhibit superior photodegradative, antibacterial and antioxidant activities. © 2014 Elsevier B.V. All rights reserved. Source


Suresh D.,Tumkur University | Nethravathi P.C.,Tumkur University | Udayabhanu,Tumkur University | Rajanaika H.,Tumkur University | And 3 more authors.
Materials Science in Semiconductor Processing | Year: 2014

The present study involves green synthesis of ZnO nanoparticles (Nps) using aqueous Cassia fistula plant extract as fuel by solution combustion synthesis. The ZnO Nps were characterized by Powder X- ray diffraction (PXRD), UV-visible studies and Transmission electron microscopy (TEM). The Nps were evaluated for photodegradative, antimicrobial and antioxidant activities. The extract was found to contain reducing components such as polyphenols (11%) and flavonoids (12.5%). The Nps were found to have a hexagonal wurtzite structure. UV-visible absorption of ZnO Nps showed absorption band at 370 nm which can be assigned to the intrinsic band-gap absorption of ZnO due to the electron transitions from the valence band to the conduction band. TEM image confirms the formation of nanoparticles and the average crystallite sizes were found to be ~5-15 nm. Methylene blue (MB) dye was effectively degraded under UV and Sun light illumination in the presence of ZnO Nps. Significant antioxidant activity was exhibited by Nps through scavenging of 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals. Excellent bactericidal activity was shown by the Nps on Klebsiella aerogenes, Escherichia coli, Plasmodium desmolyticum and Staphylococcus aureus. Synthesis of multifunctional ZnO Nps using naturally occurring plant products has been advocated as a possible environment friendly alternative to chemical methods. © 2014 Elsevier Ltd. Source

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