Faculty Publications
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Item The fabrication, characterization and electrochemical corrosion behavior of Zn-TiO2 composite coatings(2011) Punith Kumar, M.K.; Venkatesha, T.V.; Pavithra, M.K.; Nithyananda Shetty, A.Metal-nanoparticle composite coatings improve the hardness, wear resistance and corrosion resistance properties of metal coatings. In this work, TiO 2 nanoparticles were chosen as second-phase particles to generate anticorrosive Zn composite coatings. The TiO2 nanoparticles were dispersed in a Zn plating solution to co-deposit them with Zn. The Zn-TiO 2 composite coatings were then characterized by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction methods. The presence of TiO2 particles in the composite was confirmed by SEM images and EDS spectra. The Zn-TiO2 composite coatings incorporated with different amounts of TiO2 particles were tested for corrosion performance by polarization and electrochemical impedance spectroscopy, and the dissolution behavior of the coatings that had been immersed in corrosive media for a long time was studied. Improved corrosion resistance properties of the Zn-TiO2 composite coatings were confirmed by polarization studies, fitted Nyquist plots, an increase in phase angle and a shift in the Rct characteristic peak of the Bode plot. © 2011 The Royal Swedish Academy of Sciences.Item Eclipta prostrata leaf aqueous extract mediated synthesis of titanium dioxide nanoparticles(2012) Govindasamy, G.; Rahuman, A.A.; Priyamvada, B.; Khanna, V.G.; Devarepally, D.K.; Jose, P.J.Eco-friendly, nontoxic, inexpensive, abundantly available hitherto unreported Eclipta prostrata leaf extract is used for the biosynthesis of titanium dioxide nanoparticles (TiO 2 NPs). The TiO 2 NPs were characterized by FTIR, XRD, AFM and FESEM analysis. FTIR peak implicated the role of carboxyl group OH stretching amine NH stretch in the formation of TiO 2 NPs. XRD characterized in crystallographic plane of rutile phase. AFM showed uneven surface morphology which indicates the presence of both individual and agglomerated nanoparticles. FESEM analysis showed shape in spherical clusters, quite polydisperse and it ranges in size from 36 to 68 nm with calculated average size of 49.5 nm. In this paper, we have demonstrated a novel biological route for the synthesis of TiO 2 NPs. © 2011 Elsevier B.V. All rights reserved.Item Microwave synthesized nanostructured TiO 2 -activated carbon composite electrodes for supercapacitor(Elsevier B.V., 2012) Muthu, M.; Bhat, D.K.Electrochemical properties of a supercapacitor based on nanocomposite electrodes of activated carbon with TiO 2 nano particles synthesized by a microwave method have been determined. The TiO 2 /activated carbon nanocomposite electrode with a composition of 1:3 showed a specific capacitance 92 Fg -1 . The specific capacitance of the electrode decreased with increase in titanium dioxide content. The p/p symmetrical supercapacitor fabricated with TiO 2 /activated carbon composite electrodes showed a specific capacitance of 122 Fg -1 . The electrochemical behavior of the neat TiO 2 nanoparticles has also been studied for comparison purpose. The galvanostatic charge-discharge test of the fabricated supercapacitor showed that the device has good coulombic efficiency and cycle life. The specific capacitance of the supercapacitor was stable up to 5000 cycles at current densities of 2, 4, 6 and 7 mA cm -2 . © 2012 Elsevier B.V.Item Permeation, Antifouling and desalination performance of TiO2 nanotube incorporated PSf/CS blend membranes(2013) Kumar, R.; Isloor, A.M.; A.F., A.F.; Abdul Rashid, S.A.; Ahmed, A.A.Polysulfone (PSf) and chitosan (CS) blend membranes were prepared by incorporating titanium dioxide nanotubes (TiO2NT) in different compositions. The proper blending of PSf and CS in the PSf/CS/TiO2 membranes was confirmed by ATR-IR spectroscopy. The influence of nanotubes on morphology of membranes was investigated by Field Emission Scanning Electron Microscopy (FESEM). The effect of nanotubes on hydrophilicity of the membranes was studied by water swelling and contact angle measurements. The distribution of TiO2NT on the membrane surface was determined by Transmission Electron Microscope (TEM) analysis. The permeation property of PSf/CS/TiO2NT membranes was carried out by measuring the time dependent pure water flux (PWF). Bovine serum albumin (BSA) protein rejection studies were performed to know the antifouling properties. The rheological percolation threshold of PSf/CS/TiO2NT solutions was measured by viscosity studies. The nanotubes incorporated PSf/CS membranes showed enhanced permeation and antifouling properties compared to PSf/CS and nascent PSf ultrafiltration membranes. Membranes prepared well above rheological percolation threshold showed drastic reduction in pore size and acted as nanofiltration (NF) membranes. © 2013 Elsevier B.V.Item Solar light induced photocatalytic degradation of Reactive Blue 220 (RB-220) dye with highly efficient Ag@TiO2 core-shell nanoparticles: A comparison with UV photocatalysis(2014) Khanna, A.; Shetty K, K.Ag core-TiO2 shell (Ag@TiO2) structured nanoparticles with Ag to TiO2 molar ratio of 1:1.7 were synthesized using one pot synthesis method and post calcination was carried out at 450°C for 3h to convert it from amorphous to crystalline form. The Ag core and TiO2 shell formation was confirmed by TEM and AFM. The particle size analysis revealed the average size of Ag@TiO2 as approximately around 30nm. EDS spectra showed the presence of O, Ag, and Ti elements. The improvement in optical properties was proved by DRS which showed significant red shift by Ag core in visible region. Ag@TiO2 exhibited better photocatalytic activity as compared to Degussa P25-TiO2, synthesized TiO2, and the Ag doped TiO2 photocatalysts under UV and solar light irradiation for degradation of Reactive Blue 220 (RB-220) dye. Higher rate of photocatalysis of RB-220 with Ag@TiO2 was obtained under solar light irradiation as compared to UV light irradiation, confirming the capability of the catalyst to absorb both UV and visible light. The kinetics of degradation of dye was found to follow modified Langmuir Hinshelwood (L-H) kinetic model. Ag@TiO2 can be recycled without much decline in the efficacy. Ag@TiO2 has been found to be the effective photocatalyst for degradation of water contaminated with azo dyes under both UV and solar light irradiations. © 2013 Elsevier Ltd.Item 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.Item Preparation and performance studies of polysulfone-sulfated nano-titania (S-TiO2) nanofiltration membranes for dye removal(Royal Society of Chemistry, 2015) Pereira, V.R.; Isloor, A.M.; Bhat, K.U.; A.F., A.F.; AlObaid, A.; Fun, H.-K.Polysulfone nanofiltration membranes containing sulfated nano-titania (S-TiO2) were fabricated, with the aim to enhance the membrane properties along with the possible rejection of Methylene Blue (MB) dye by membranes. Initially S-TiO2 was synthesized from nano TiO2 by the action of sulfuric acid. The synthesized S-TiO2 was characterized by Fourier Transform Infrared spectroscopy (FT-IR), Energy Dispersive Spectrophotometry (EDS) and Transmission Electron Microscopy (TEM) analysis. S-TiO2 was added in increasing concentrations into the membranes and its effect on the performance of the membranes was evaluated. The synthesized membranes were characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Polysulfone membranes containing S-TiO2 showed enhancement in properties in terms of hydrophilicity, water uptake, mechanical strength, improved pure water flux (PWF), antifouling nature and high Flux Recovery Ratio (FRR). The polysulfone membranes with S-TiO2 showed 99% rejection for BSA (Bovine Serum Albumin) protein molecules during BSA filtration. The prepared membranes were used for the removal of MB dye from aqueous solutions. A maximum of 90.4% rejection was obtained for MB for the membrane having 2.0 wt% of S-TiO2 under UV light radiation. This approach showed that polysulfone-S-TiO2 membranes displayed good efficiency for dye removal and can be effectively used for the removal of MB dye from aqueous solutions under suitable conditions. © The Royal Society of Chemistry.Item Anticorrosion Performance of Electrochemically Produced Zn-1% Mn-Doped TiO2 Nanoparticle Composite Coatings(Springer New York LLC barbara.b.bertram@gsk.com, 2015) Punith Kumar, M.K.; Venkatesha, T.V.; Pavithra, M.K.; Nithyananda Shetty, A.The Zn-TiO2 composite coatings were electrodeposited on mild steel using sulfate plating bath dispersed with 1% Mn-doped TiO2 nanoparticles. The agglomeration state and charge on the particles in plating condition were analyzed by zeta potential and particle size distribution measurements. The change in microstructure and morphology in composite coatings was analyzed by x-ray diffraction, energy-dispersive x-ray diffraction, and Scanning electron microscopic analyses. The corrosion behavior of the coatings was tested by electrochemical methods such as Tafel polarization and Electrochemical Impedance study. The increased charge transfer resistance with reduced corrosion rate was observed for composite coatings compared to pure zinc coating. The morphology and corrosion behavior of the composite coatings are correlated with pure zinc coating properties. © 2015, ASM International.Item Superior Photostability and Photocatalytic Activity of ZnO Nanoparticles Coated with Ultrathin TiO2 Layers through Atomic-Layer Deposition(Wiley-VCH Verlag info@wiley-vch.de, 2015) Sridharan, K.; Jang, E.; Park, Y.M.; Park, T.J.Atomic-layer deposition (ALD) is a thin-film growth technology that allows for conformal growth of thin films with atomic-level control over their thickness. Although ALD is successful in the semiconductor manufacturing industry, its feasibility for nanoparticle coating has been less explored. Herein, the ALD coating of TiO2 layers on ZnO nanoparticles by employing a specialized rotary reactor is demonstrated. The photocatalytic activity and photostability of ZnO nanoparticles coated with TiO2 layers by ALD and chemical methods were examined by the photodegradation of Rhodamine B dye under UV irradiation. Even though the photocatalytic activity of the presynthesized ZnO nanoparticles is higher than that of commercial P25 TiO2 nanoparticles, their activity tends to decline due to severe photocorrosion. The chemically synthesized TiO2 coating layer on ZnO resulted in severely declined photoactivity despite the improved photostability. However, ultrathin and conformal ALD TiO2 coatings (?0.75-1.5 nm) on ZnO improved its photostability without degradation of photocatalytic activity. Surprisingly, the photostability is comparable to that of pure TiO2, and the photocatalytic activity to that of pure ZnO. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticles(Royal Society of Chemistry, 2016) Elias, L.; Hegde, A.This work reports the modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticle incorporation. The first part is devoted to optimization of a new citrate bath for the development of an efficient electroactive Ni-P electrode material by electrodeposition, using glycerol as an additive. The Ni-P alloys developed at 4.0 A dm-2 and 2.0 A dm-2 were found to be good for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively as demonstrated by cyclic voltammetry (CV) and chronopotentiometry (CP) methods. The Ni-P alloy showing good catalytic activity for HER is found to be less active for OER and vice versa. The unique electrocatalytic property of the coatings was attributed to its structure, morphology and composition, confirmed by XRD, SEM and EDS analyses. In the second part, the electrocatalytic activity of Ni-P alloy coatings for HER has been improved further by anodic dissolution and TiO2 nanoparticle incorporation. Drastic improvement in the electrocatalytic activity for HER was found in both anodically treated and Ni-P-TiO2 composite coatings, compared to as-coated Ni-P alloys. The highest electrocatalytic character of the Ni-P-TiO2 composite coating was attributed to a greater number of electroactive centres, affected by TiO2 nanoparticle incorporation, and experimental results are discussed. © The Royal Society of Chemistry 2016.