N.B. Arun Kumar; J. Sirajudeen; H.P. Nagaswarupa; C.R. Ravikumar; M.R. Anil Kumar; H.C. Ananda Murthy
Abstract
We report the successful synthesis of NiO nanomaterial by combustion method using Plectranthus amboinicus plant leaves extract. The diffraction pattern and image analysis confirmed the FCC lattice structure for green NiO nanomaterial (g-NONM) with spongy, agglomerated and porous nature. The average energy ...
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We report the successful synthesis of NiO nanomaterial by combustion method using Plectranthus amboinicus plant leaves extract. The diffraction pattern and image analysis confirmed the FCC lattice structure for green NiO nanomaterial (g-NONM) with spongy, agglomerated and porous nature. The average energy band gap of g-NONM was found to be 4.10 eV. The electrode made of g-NONM exhibited excellent stability in addition to its good reversibility. The g-NONM showed superior photo-decolarisation results for AO dye solution with 33.95 % dye decolorization at 405 nm. The obtained rate constant k value of g-NONM for AO dye is 0.002933 min −1 . The prepared g-NONM electrode showed a minimum charge-transfer resistance which is possibly due to its high conductivity as supported by electrochemical impedance studies. The NiO electrode also exhibited very high alcohol sensing ability in alkaline medium as revealed during CV measurement. The best part of the study was the fast reply (3 s) of the prepared electrode in sensing the drugs at 1 mM concentration solution. In addition, g-NONM can be easily fabricated into stable electrode material for supercapacitors applications. The results suggested that g-NONM can be an efficient and cheaper material for photocatalytic, sensor and supercapacitor applications.
Xin X. Yu; Fang Z. Dong; Bao Dong; Liang Liu; Yan Wu
Abstract
Natural hematite ore is used as a novel material for visible photocatalyst. The hematite was composited with needle-shaped ZnO via a hydrothermal approach. This hematite-based system exhibits excellent photodegradation for rhodamine (RhB) within 30 min when the hematite is hybridized with wurtzite -structured ...
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Natural hematite ore is used as a novel material for visible photocatalyst. The hematite was composited with needle-shaped ZnO via a hydrothermal approach. This hematite-based system exhibits excellent photodegradation for rhodamine (RhB) within 30 min when the hematite is hybridized with wurtzite -structured ZnO under visible light irradiation. The formation of a hybrid hetero-junction was shown by transmission electron microscope. The photocatalytic activity of the hetero-junction was evaluated by the photodegradation of RhB dye. The high photocatalytic activity observed under visible light is discussed on basis of the coupling of the hybrid hetero-junction band structure.
Samuel O.B. Oppong; William W. Anku; Sudheesh K. Shukla; Poomani P. Govender
Abstract
La-TiO2-GO nanocomposites were successfully synthesised via sol-gel method. Structures, morphologies and photocatalytic activities of the as-synthesized nanocomposites were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (RS) and scanning electron ...
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La-TiO2-GO nanocomposites were successfully synthesised via sol-gel method. Structures, morphologies and photocatalytic activities of the as-synthesized nanocomposites were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (RS) and scanning electron microscopy (SEM). UV-Vis diffuse reflectance spectroscopy was used to estimate band gap energies. The photocatalytic activities of the as-synthesized nanocomposites were evaluated for the degradation of Acid Blue 40 in aqueous solutions under simulated solar light. The photocatalytic results show that the as-synthesized La-doped TiO2-GO (0.3% La) nanocomposite shows good photocatalytic activity and can be considered as a promising photocatalyst for the degradation of organic pollutants in water. The good photocatalytic efficiency is ascribed to the cooperative effect of improved visible light absorbance and separation of charge carriers due to the combined effect of La and the GO in the composite. Analysis from Total organic carbon (TOC) shows a high degree of complete mineralisation of Acid Blue 40 (TOC removal of 75%) which decreases the formation of possible degradation by-products. Due to the stability of La-TiO2-GO (0.3% La) nanocomposite, it was reused for five times reaching 84.0% maximum degradation efficiency during the five cycles.
P. V. Ramana; A. Viswadevarayulu; K. Kumar; S. Adinarayana Reddy
Abstract
The potential of a novel photocatalyst graphene-ZnO (G-ZnO) obtained from graphene oxide and zinc acetate dihydrate was investigated for the reduction of heavy metal Cr(VI) ions from water. In which ZnO nanocubic crystals were finely doped on the graphene sheets, was well done by facile wet chemical/reflux ...
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The potential of a novel photocatalyst graphene-ZnO (G-ZnO) obtained from graphene oxide and zinc acetate dihydrate was investigated for the reduction of heavy metal Cr(VI) ions from water. In which ZnO nanocubic crystals were finely doped on the graphene sheets, was well done by facile wet chemical/reflux method under N2 atmosphere. Due to hindered nature of photo-generated electron-hole pair recombination and enhanced light absorption shows efficient photocatalytic performance of G-ZnO nanocomposites (NCs) in the reduction of Cr(VI) ions with a degradation rate of 98% under daylight illumination as related with bare ZnO (42%), graphene oxide (GO) (19%) and mechanical mixture GO+ZnO (62%). The overall results demonstrated that the photocatalyst used in this study, is promising, efficient and economical when used to separate heavy metal ions from water.
Y. P. Tsai; J. C. Yang; P. C. Chuang; C. C. Chou; J. W. Lin
Abstract
This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, ...
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This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, are further calculated in the study. The ΔH 0 data showed the adsorption of HA onto MWCNTs is an endothermic physisorption. The ΔG 0 data indicates the adsorption of HA onto MWCNTs was spontaneous and thermodynamically favorable. Photocatalytic experiments showed 60 mgl -1 of HAs were completely degraded and mineralized as CO2 after 5 h UV irradiation by 0.8 gl -1 of TiO2, indicating the efficiency of TiO2 for the removal of HA is better than CNTs. The experiments of TiO2/CNT indicated the photocatalytic efficiency of TiO2 in the presence of CNTs was not improved, even worse than TiO2 alone. However, the photocatalytic efficiency of TiO2/CNT mixture became better than TiO2 alone due to the supply of oxygen by aeration, ascribing to the reason that the provided oxygen might be adsorbed on the surface of CNTs and accept e- as well as form •O2 - , which also leads to the formation of •OH - in the system.
Hyun-Je Sung; Sang-Chul Jung;Jung-Sik Kim; Byung-Min Ki
Abstract
The photocatalytic behaviors of TiO2-supported on the long lasting phosphor beads were examined. Nanocrystalline TiO2 was coated on ellipsoidal-spherical beads of an alkaline earth aluminate phosphor, Sr4Al14O25:Eu 2+ , Dy 3+ , by low pressure chemical vapor deposition (LPCVD). The photocatalytic reaction ...
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The photocatalytic behaviors of TiO2-supported on the long lasting phosphor beads were examined. Nanocrystalline TiO2 was coated on ellipsoidal-spherical beads of an alkaline earth aluminate phosphor, Sr4Al14O25:Eu 2+ , Dy 3+ , by low pressure chemical vapor deposition (LPCVD). The photocatalytic reaction was examined by measuring the decomposition of benzene and toluene gases by gas chromatography under ultraviolet, visible light (λ> 410 nm) irradiation, as well as in the dark. The LPCVD TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ showed an active photocatalytic reaction under visible irradiation. The mechanisms of the photocatalytic reactivity for the TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ phosphor beads were discussed in terms of the crystal structure at the interface, energy band structure and phosphorescence. The coupling of TiO2 with the Sr4Al14O25:Eu 2+ , Dy 3+ phosphor resulted in energy band bending in the junction region between TiO2 and Sr4Al14O25:Eu 2+ , Dy 3+ phosphor, which makes the TiO2 crystal at the interface photo-reactive under visible light irradiation. The LPCVD TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ phosphor beads were also photo-reactive in the dark through the light photons emitted from the Sr4Al14O25:Eu 2+ , Dy 3+ phosphor.
K. Chennakesavulu; G. Ramanjaneya Reddy; S. Sanjeevi Prasath; S. Supriya; S. Sivanesan
Abstract
In-situ synthesis of ZnO and Nb2O5 composites was carried out in alkaline medium. The obtained composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy ...
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In-situ synthesis of ZnO and Nb2O5 composites was carried out in alkaline medium. The obtained composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area method, N2-sorption isotherms, Thermo gravimetric analysis (TGA), Particle size and Field emission scanning electron microscopy (FESEM/EDX). The synthesized composite was used as photocatalyst in the degradation of reactive red-198 (RR), methylene blue (MB) and 3-chloro phenol (3CP) under visible light irradiation. The catalytic activity and removal percentage of dye was determined by the spectrophotometric method, it indicates high percentage of degradation for the ZnO:Nb2O5 composite. The kinetic parameters were found to obey pseudo-first order oxidation reaction, which may be due to the fixed amount of the catalyst and concentration of the dye solution. The recycled and purified composites of ZnO:Nb2O5 was tested the catalytic activity and was compared with that of the fresh catalyst.
Shashi Kant;Amit Kumar
Abstract
Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission ...
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Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission Emission Microscopy (TEM) .Due to doping of ZnO nanoparticles the absorption shifted towards the visible region from UV region .The absorption increases on doping in the visible region.The Photocatalytic activity of both the doped and undoped ZnO was analysed via degradation of Methylene Blue. The Methylene Blue decomposition rate of pure ZnO and Nickel doped ZnO nanoparticles were studied under UV –Visible region. In the visible region both pure and doped ZnO decomposed Methylene Blue.This confirms the potential application of ZnO Nanoparticles for removal of harmful dyes from waste water and drinking water.The doping has a pronounced effect on the photocatalytic activity of nanoparticles. The degradation rate of the dye increased in case of Ni doped ZnO nanospheres.
