Browsing by Author "Huang, N.M."

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Fabrication, characterization and catalytic activity of ?-MnO2 nanowires for dye degradation of reactive black 5
(2016) Ramesh, M.; Nagaraja, H.S.; Rao, M.P.; Anandan, S.; Huang, N.M.
?-MnO2 nanowires (NWs) prepared by hydrothermal method are characterized using XRD and FT-IR. The crystallite size, surface area of NWs increases, whereas dislocation density and band gap decreases with an increase in oxidizer molarity. The band gap decreases from 2.55 to 1.27 eV. The above observations correlate well with the enhanced catalytic activity of MnO2 NWs for degradation of azo dye reactive black 5 (RB5). About 70% of the dye were successfully removed in 60 min using 20 mg of MnO2 NWs in the presence of 6 mL of H2O2. MnO2 NWs show a good reusability, suggesting it as an effective and recyclable catalyst. 2016 Elsevier B.V. All rights reserved.
Fabrication, characterization and catalytic activity of ?-MnO2 nanowires for dye degradation of reactive black 5
(Elsevier B.V., 2016) Ramesh, M.; Nagaraja, H.S.; Rao, M.P.; Anandan, S.; Huang, N.M.
?-MnO2 nanowires (NWs) prepared by hydrothermal method are characterized using XRD and FT-IR. The crystallite size, surface area of NWs increases, whereas dislocation density and band gap decreases with an increase in oxidizer molarity. The band gap decreases from 2.55 to 1.27 eV. The above observations correlate well with the enhanced catalytic activity of MnO2 NWs for degradation of azo dye reactive black 5 (RB5). About 70% of the dye were successfully removed in 60 min using 20 mg of MnO2 NWs in the presence of 6 mL of H2O2. MnO2 NWs show a good reusability, suggesting it as an effective and recyclable catalyst. © 2016 Elsevier B.V. All rights reserved.
Influence of Sn doping on photoluminescence and photoelectrochemical properties of ZnO nanorod arrays
(2014) Kumar, A.S.; Huang, N.M.; Nagaraja, H.S.
Herein, the nanostructured Sn containing ZnO is directly synthesized on the surface of substrate by modified sol gel approach under low-temperature condition. The samples are characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman-scattering, photoluminescence (PL) and photoelectrochemical analyses. The SEM micrographs show that the undoped and 1 at. % Sn doped films are composed of nanorods and the concentration of 2 at. % Sn doping hinders the rod-like structure's growth and modulates into granular nature. The investigations of XRD reveal that the synthesized undoped and Sn doped ZnO nanorods possess a perfect hexagonal growth habit of wurtzite zinc oxide, along the (002) direction of preference. The Raman spectra demonstrate that the vibrational mode of E1(LO), which is very weak in undoped and 1at. % Sn doped ZnO, is strongly enhanced with 2 at. % Sn doping into ZnO lattice. PL spectra show that strong UV emission in pure and 1 at. % Sn doped ZnO, while there is dominant green emission in 2 at. % Sn doped ZnO. Moreover, all the samples are photo electrochemically active and exhibit the highest photocurrent of 28 ?A for the 1 at. % Sn doped ZnO nanorod arrays in 0.2M Na2SO4 electrolyte, on light irradiation. Time dependent photoresponse tests are carried out by measuring the photocurrent under chopped light irradiation. 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.
Influence of Sn doping on photoluminescence and photoelectrochemical properties of ZnO nanorod arrays
(Kluwer Academic Publishers, 2014) Santhosh Kumar, A.S.; Huang, N.M.; Nagaraja, H.S.
Herein, the nanostructured Sn containing ZnO is directly synthesized on the surface of substrate by modified sol gel approach under low-temperature condition. The samples are characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman-scattering, photoluminescence (PL) and photoelectrochemical analyses. The SEM micrographs show that the undoped and 1 at. % Sn doped films are composed of nanorods and the concentration of 2 at. % Sn doping hinders the rod-like structure's growth and modulates into granular nature. The investigations of XRD reveal that the synthesized undoped and Sn doped ZnO nanorods possess a perfect hexagonal growth habit of wurtzite zinc oxide, along the (002) direction of preference. The Raman spectra demonstrate that the vibrational mode of E1(LO), which is very weak in undoped and 1at. % Sn doped ZnO, is strongly enhanced with 2 at. % Sn doping into ZnO lattice. PL spectra show that strong UV emission in pure and 1 at. % Sn doped ZnO, while there is dominant green emission in 2 at. % Sn doped ZnO. Moreover, all the samples are photo electrochemically active and exhibit the highest photocurrent of 28 ?A for the 1 at. % Sn doped ZnO nanorod arrays in 0.2M Na2SO4 electrolyte, on light irradiation. Time dependent photoresponse tests are carried out by measuring the photocurrent under chopped light irradiation. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.
Preparation, characterization and photoelectrochemical properties of hydrophilic Sn doped TiO2 nanostructures
(2014) Kumar, A.S.; Nagaraja, K.K.; Huang, N.M.; Nagaraja, H.S.
Abstract Hydrophilic Sn doped TiO2 nanostructured thin films have been fabricated using a sol-gel method, and followed by calcination at 450 C. The samples are characterized by means of XRD, Raman, SEM and contact angle measurements. The XRD and Raman studies revealed that, the higher Sn doping content (3 at%) leads to the formation of mixed phases of TiO2. SEM micrographs revealed that all samples are porous in nature. The contact angle of TiO2 nanostructured films varied between 19 and 37 depending upon the Sn content. All the samples are photoelectrochemically active and 2% Sn doping significantly enhances the photoelectrochemical ability of TiO 2 film. The highest photocurrent density of 20 ?A cm-2 is measured for 2 at% Sn doped TiO2 in 0.2 M Na2SO 4 electrolyte, on light irradiation. Time dependent photoresponse tests have been carried out by measuring the photocurrent under chopped light irradiation. 2014 Elsevier B.V.
Preparation, characterization and photoelectrochemical properties of hydrophilic Sn doped TiO2 nanostructures
(Elsevier, 2014) Santhosh Kumar, A.S.; Nagaraja, K.K.; Huang, N.M.; Nagaraja, H.S.
Abstract Hydrophilic Sn doped TiO2 nanostructured thin films have been fabricated using a sol-gel method, and followed by calcination at 450 C. The samples are characterized by means of XRD, Raman, SEM and contact angle measurements. The XRD and Raman studies revealed that, the higher Sn doping content (3 at%) leads to the formation of mixed phases of TiO2. SEM micrographs revealed that all samples are porous in nature. The contact angle of TiO2 nanostructured films varied between 19 and 37 depending upon the Sn content. All the samples are photoelectrochemically active and 2% Sn doping significantly enhances the photoelectrochemical ability of TiO 2 film. The highest photocurrent density of 20 ?A cm-2 is measured for 2 at% Sn doped TiO2 in 0.2 M Na2SO 4 electrolyte, on light irradiation. Time dependent photoresponse tests have been carried out by measuring the photocurrent under chopped light irradiation. © 2014 Elsevier B.V.
Solar exfoliated graphene and its application in supercapacitors and electrochemical H2O2 sensing
(2015) Sreejesh, M.; Huang, N.M.; Nagaraja, H.S.
In the present study, graphene nanosheets are synthesized using sunlight irradiation focussed onto graphite oxide. The morphological characteristics of graphene are examined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Raman spectroscopy and X-ray diffraction (XRD) are used for the structural characterization of the sample. The electrochemical performance is evaluated using cyclic voltammetry (CV), charge-discharge characteristics and impedance spectroscopy. A high specific capacitance value of 223 F g-1 is obtained using cyclic voltammetry. The electrochemical detection of H2O2, a common biological species using solar graphene is demonstrated. The impedance spectroscopy and CV are used to study the electrocatalytic activity of the material. High sensitivity of 64.79 ?A mM-1 cm-2 is reported. 2015 Elsevier Ltd. All rights reserved.
Solar exfoliated graphene and its application in supercapacitors and electrochemical H2O2 sensing
(Elsevier Ltd, 2015) Moolayadukkam, M.; Huang, N.M.; Nagaraja, H.S.
In the present study, graphene nanosheets are synthesized using sunlight irradiation focussed onto graphite oxide. The morphological characteristics of graphene are examined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Raman spectroscopy and X-ray diffraction (XRD) are used for the structural characterization of the sample. The electrochemical performance is evaluated using cyclic voltammetry (CV), charge-discharge characteristics and impedance spectroscopy. A high specific capacitance value of 223 F g-1 is obtained using cyclic voltammetry. The electrochemical detection of H2O2, a common biological species using solar graphene is demonstrated. The impedance spectroscopy and CV are used to study the electrocatalytic activity of the material. High sensitivity of 64.79 ?A mM-1 cm-2 is reported. © 2015 Elsevier Ltd. All rights reserved.